BIOLOGY  LIBRARY 


GIFT 


A  TEXT-BOOK 

OF 

MEDICAL  CHEMISTRY 

AND 

TOXICOLOGY 


BY 


JAMES  W.  HOLLAND,  A.M.,  M.D. 

PROFESSOR    OF    MEDICAL    CHEMISTRY   AND   TOXICOLOGY,    AND    DEAN, 
JEFFERSON   MEDICAL   COLLEGE,    PHILADELPHIA 


FULLY   ILLUSTRATED 


THIRD  EDITION,  THOROUGHLY  REVISED 


PHILADELPHIA  AND   LONDON 

W.  B.  SAUNDERS   COMPANY 

1911 


T-' 
I  <*• 

BIOLOGY 


Copyright,  1905,  by  W.  B.  Saunders  and  Company.      Reprinted  January,  1906. 
Revised,  reprinted,  and  recopyrighted  August,  1908.      Reprinted 
May,    1909.       Revised,    reprinted,   and   re- 
copyrighted  March,  1911. 


Copyright.  1911,  by  W.  B.  Saunders  Company. 
V 


PRINTED    IN    AMERICA 


PRESS    OF 
W.    B.    SAUNDERS    COMPANY 


TO  THE  MEMORY 


ROBERT  CHAPPELL  HOLLAND,  M.  D. 


FILIAL  RESPECT  AND  GRATITUDE 


PREFACE  TO  THE  THIRD  EDITION 


THE  changes  of  this  revision  are  limited  to  such  as  would  not 
increase  the  size  of  the  volume.  Yet  are  they  so  numerous  that, 
if  bulked  together,  one  might  call  them  considerable.  They  con- 
sist in  the  many  minor  alterations  of  the  text  found  necessary  to 
bring  it  accurately  abreast  with  the  most  recent  and  approved 
research. 


PREFACE 


ON  admission  to  the  medical  college  the  student  is  expected  to  have 
some  knowledge  of  physics.  Experience  shows  that  a  part  of  this 
information — concerned  with  chemical  questions  and  having  toxicologic 
and  therapeutic  interest — needs  to  be  refreshed  and  enlarged. 

The  remarkable  developments  of  physical  science  in  recent  years 
have  furnished  the  practical  sciences  with  working  principles  of  great 
value,  which  are  being  applied  successfully  to  biologic  problems  in 
bacteriology,  toxicology,  and  pharmacodynamics.  Cryoscopy,  osmotic 
pressure,  electrolytic  dissociation,  mass-action,  radio-activity,  have  not 
been  recognized  hitherto  as  part  of  the  preparatory  studies,  and  hence 
should  find  a  place  in  the  medical  text-book  to  the  extent,  at  least,  of 
a  compendious  statement  of  the  principles  involved. 

It  is  desirable  that  some  exposition  should  be  given  of  the  results, 
as  well  as  an  underlying  knowledge  of  methods.  All  that  has  been 
included  within  the  scope  of  this  work  is  little  more  than  a  foundation 
for  those  who  choose  to  build  upon  it  hereafter.  This  must  be  a  growing 
class,  for  there  is  great  hope  of  medical  progress  in  this  direction.  The 
discoveries  of  Arrhenius,  Van  t'Hoff,  and  Ostwald  have  been  the  point 
of  departure  for  the  biologic  researches  of  Loeb  and  Pauli,  and  the 
medical  studies  of  Koranyi,  Hamburger,  and  Zikel.  Those  who  wish 
to  pursue  these  fascinating  studies  further  are  referred  to  Walker's 
Introduction  to  Physical  Chemistry;  H.  C.  Jones'  Elements  of  Physical 
Chemistry;  Ostwald's  Principles  of  Inorganic  Chemistry;  Cohen's 
Physical  Chemistry;  and  Zikel's  Clinical  Osmology. 

It  cannot  be  taken  for  granted  that  all  beginners  in  medicine  have 
an  adequate  preparation  in  elementary  chemistry.  While  the  number 
of  those  unprepared  diminishes  annually,  it  will  be  years  before  the 
assumption  will  be  safe  that  the  teacher  of  physiologic  chemistry  and 
toxicology  in  the  medical  school  can  proceed  at  once  to  the  consideration 
of  these  practical  applications  of  the  science. 

In  the  present  work,  as  soon  as  may  be,  these  relationships  are 
brought  to  the  front.  But  the  ground  must  first  be  laid  by  the  elucid- 
ation of  chemical  philosophy.  For  lack  of  space,  many  things  have  been 

ii 


i          •    ,        . 

12  .PREFACE 

omitted  which  would  have  been  included  had  the  work  been  intended 
as  a  text-book  of  pure  chemistry.  Among  these  may  be  mentioned 
the  consideration  of  rare  elements  and  compounds  never  encountered 
in  the  study  and  practice  of  medicine.  A  due  sense  of  proportion 
requires  much  teaching  of  the  essentials  of  medical  chemistry  and 
avoidance  of  extraneous  matters  which  at  this  stage  only  complicate 
a  study  sufficiently  difficult  in  its  simplest  form. 

Much  of  the  text  relating  to  the  toxicology  of  mineral  corrosives 
and  irritants  has  already  appeared  in  the  chapter,  by  the  same  author, 
in  Legal  Medicine  and  Toxicology,  by  Peterson  and  Haines.  The 
copious  bibliographic  references  there  given  have  been  omitted  in  the 
present  work — intended  primarily  as  a  text-book  for  students.  A  part 
of  the  chapter  on  the  Urine  appeared  in  The  American  Text-book  oj 
Theory  and  Practice  oj  Medicine,  edited  by  Pepper.  Many  changes 
and  revisions  have  been  made  in  it  to  bring  it  up  to  the  line  of  present 
knowledge. 


CONTENTS 


INTRODUCTION 17 

Matter  and  Force 17 

Metrology 17 

Heat 28 

Thermometry 28 

Specific  Heat 34 

Melting  and  Freezing 35 

Evaporation 39 

Boiling 41 

Magnetism  and  Electricity 45 

The  Galvanic  Current 45 

The  Induction  Coil 52 

Cathode  and  Rontgen  Rays 53 

Light 55 

Spectroscopy 55 

Polarimetry 58 

THE  CHEMICAL  ELEMENTS 62 

The  Non-metals 65 

Oxygen 65 

Ozone  or  Allotropic  Oxygen 74 

Hydrogen 77 

Water 83 

Hydrogen  Dioxid ! . . . .  86 

Solution — Diffusion — Dialysis — Osmosis 89 

Solution 89 

Diffusion . .  .  92 

Dialysis 93 

Osmosis 94 

Nitrogen  and  the  Argon  Group 97 

Nitrogen '.....  97 

Carbon  and  its  Oxids 98 

Carbon 98 

Carbon  Monoxid 100 

Carbon  Dioxid 102 

Chemical  Philosophy 108 

Atomic  Theory 109 

Chlorin 118 

Acids,  Bases  and  Salts 123 

Dissociation 127 

13 


14  CONTENTS 

THE  CHEMICAL  ELEMENTS  (Continued).  PAGE 

The  Non-metals  (Continued}. — Hydrochloric  Acid 135 

Compounds  of  Chlorin  Containing  Oxygen 139 

Other  Halogens 142 

Bromin 142 

lodin 144 

Fluorin 148 

The  Chlorin  Family  or  Halogens 149 

Sulphur 150 

Selenium  and  Tellurium 168 

Compounds  of  Nitrogen  and  Oxygen 169 

Phosphorus 177 

Carbonic  Acid 191 

Derivatives  of  Carbonic  Acid 192 

The  Cyanogen  Group 194 

Oxalic  Acid 200 

Silicon 205 

Boron 208 

The  Metals 210 

The  Metals  of  the  Alkalis 211 

Potassium 212 

Sodium 223 

Lithium 230 

Rubidium 231 

Cesium 231 

Ammonium : 23 1 

The  Metals  of  the  Alkaline  Earths 236 

Calcium 237 

Magnesium 242 

Strontium 245 

Barium 245 

Radium 247 

The  Earth  Metals 251 

Aluminium 251 

Water  Supply 256 

The  Arsenic  Group 263 

Arsenic 263 

Antimony 291 

Tin 298 

The  Copper  Group 300 

Copper 300 

Mercury 306 

Lead 320 

Bismuth. .  ^o 

C"l  '       ^ 

Silver 333 

The  Iron  Group 337 

Iron 337 

Manganese 347 

Chromium. .  ?rn 

T  '  J 

Zmc 353 


CONTENTS  15 

THE  CHEMICAL  ELEMENTS  (Continued}.  PAGE 

The  Metals  (Continued). — Nickel 357 

Cobalt - 357 

The  Gold  Group 358 

Gold 358 

Platinum 359 

Cerium 361 

Thorium 361 

Uranium 361 

Molybdenum 362 

ORGANIC  AND  PHYSIOLOGIC  CHEMISTRY 363 

Ultimate  Analysis 363 

Organic  Formulas 367 

Classification  of  Carbon  Compounds 371 

Aliphatic  Compounds 372 

Halogen  Derivatives  of  Methane 384 

Halogen  Derivatives  of  Ethane 391 

Oxygen  Derivatives  of  the  Paraffins 367 

Alcohols 367 

Ethers 402 

Aldehyds 406 

Ketones 412 

Sulphur  Derivatives  of  the  Paraffins 414 

Fatty  Acids 417 

Organic  Acids,  not  Fatty 421 

Hydroxy-  or  Alcohol-acids 422 

Ketone-acids 426 

Fats  and  Fatty  Oils 426 

Esters 430 

Compound  Ethers — Ethereal  Salts 430 

Esters  of  Organic  Acids 432 

Carbohydrates 433 

Monosaccharid:; 434 

Disaccharids 438 

Polysaccharids 440 

Cyclic  Compounds 445 

The  Benzene  or  Aromatic  Series 445 

Benzene  Hydrocarbons 446 

Benzene  Hydroxids 453 

Oxygen  Derivatives  of  Benzene 463 

Aromatic  Alcohols 463 

Aromatic  Aldehyds 464 

Aromatic  Acids 464 

Hydroxy-  or  Phenol  Acids 467 

Polynucleated  Compounds 471 

Nitrogen  Derivatives  of  Benzene 475 

Aromatic  Amido-compounds  and  Amins 476 

Diazo-compounds 480 

Heterocyclic  Compounds 483 


1 6  CONTENTS 

ORGANIC  CHEMISTRY  (Continued).  PAGE 

Cyclic  Compounds  (Continued). — Pyridin  and  its  Derivatives.   483 

Purins  and  Uric  Acid 488 

Ammonia  Derivatives 494 

Amids,   Amins,    Amino-acids,  and  Alkaloids 494 

Alkaloids 501 

Pyridin  Alkaloids 504 

Piperidin  Alkaloids 504 

Pyrrolidin-Pyridin  Alkaloids 505 

Pyrrolidin-Piperidin  Alkaloids 506 

Quinolin  Alkaloids 508 

Phenanthrene  Alkaloids 512 

Alkaloids  of  Unknown  Constitution 515 

Ptomains 517 

Toxins 520 

Proteins  and  Albuminous  Matter 524 

Ferments  or  Enzyms 535 

ENERGY  OF  FOODS 539 

Digestion 542 

Saliva 543 

Gastric  Contents 544 

Pancreatic  Juice 555 

Bile 558 

Intestinal  Juice 559 

Blood 561 

Milk 564 

Urine ' 576 


INDEX 629 


MEDICAL  CHEMISTRY 

AND 

TOXICOLOGY 


INTRODUCTION 

MATTER  AND  FORCE 

Matter  is  anything  that  has  weight,  or  anything  that  has 
length,  breadth,  and  thickness;  in  other  words,  anything  that 
occupies  space  and  is  perceptible  to  the  senses.  Matter  is  never 
absolutely  at  rest.  If  not  the  body  in  its  mass,  at  least  its  particles 
are  in  incessant  agitation. 

Energy  or  force  is  that  which  gives  matter  its  properties. 
Matter  is  thus  resolved  into  a  "mode  of  motion."  Energy  comes 
from  work  and  can  be  changed  to  work.  Such  material  changes 
as  are  caused  by  the  energy  of  heat,  light,  electricity,  magnetism, 
and  mechanical  motion  are  said  to  be  physical,  while  others  are 
called  chemical.  For  the  sake  of  simplicity  those  changes  called 
physical  are  dealt  with  in  that  branch  of  science  known  as  physics, 
but  as  some  of  them  are  very  closely  related  to  chemical  changes, 
a  thorough  study  of  the  latter  necessarily  involves  some  knowl- 
edge of  the  physical  changes. 

The  universal  ether  is  the  thin  elastic  medium  pervading 
matter  and  space  and  through  which  radiant  energy  is  transmitted 
in  waves. 

METROLOGY 

Chemistry  deals  with  the  properties  and  composition  of  sub- 
stances and  the  operations  which  produce  change  of  constitution. 

Substances  are  known  by  their  properties,  such  as  color,  form, 
hardness,  weight,  taste,  odor,  solubility,  melting-point,  boiling- 
point,  and  behavior  in  the  presence  of  active  chemicals.  In 
studying  the  composition  of  a  body,  the  properties  of  its  compo- 
2  17 


1 8  INTRODUCTION 

nents,  and  the  operation  of  chemical  force,  there  is  frequent 
occasion  to  make  estimates  of  volume  and  weight,  and  that  relation 
between  the  two  called  specific  gravity.  Metrology  is  the  science 
which  deals  with  the  means  employed  for  this  purpose. 

Weights  and  the  Balance. — In  determining  the  quantity  of 
matter  present  resort  is  had  to  the  balance.  In  this  instrument 
an  inflexible  horizontal  beam  is  poised  at  its  middle  by  a  knife- 
edge,  resting  on  a  hard  plate  at  the  top  of  an  upright  support. 
The  beam  carries  at  each  end  a  scale-pan  suspended  by  cords 
or  rods  to  the  sharp-edged  hook  which  freely  swings  from  a  steel 
pin. 

In  one  scale-pan  is  put  the  body  to  be  weighed,  in  the  other, 
masses  of  matter  called  weights,  which  have  been  previously 
marked  according  to  some  standard.  If  the  gravitation  to  the 
earth  of  the  body  to  be  weighed  and  the  weight  be  equal,  the 
vertical  index  oscillates  evenly  over  its  graduated  arc,  and  the 
beam  comes  to  an  equipoise  in  a  horizontal  position. 

The  attraction  of  gravitation  is  directly  proportionate  to  the 
mass.  As  the  weight  of  a  body  is  the  effect  of  this  downward 
force,  it  is  plain  that  mass  and  weight  will  increase  and  diminish 
together.  A  double  amount  of  matter  requires  a  double  weight 
to  balance  it,  and  one-half  the  weight  equals  one-half  the  mass 
or  quantity  of  matter. 

The  Chemist's  Balance. — In  the  ordinary  balance  the  poise  is 
not  disturbed  by  slight  variations  in  weight.  Hence  for  commer- 
cial purposes,  where  time  is  to  be  saved  and  minute  quantities  are 
more  or  less  unimportant,  a  less  sensitive  instrument  is  preferred. 
But  in  chemical  analysis  accuracy  is  to  be  desired  above  all  things. 
For  this  purpose  the  beam  of  the  balance  is  made  as  light  as 
possible,  the  bearings  are  sharp  and  hard,  the  adjustments  capable 
of  being  brought  to  the  last  degree  of  refinement,  the  instrument 
provided  with  appliances  for  arresting  its  action  at  will,  and  the 
whole  enclosed  in  a  glass  case  for  protection  from  dust,  for  exclu- 
sion of  moisture,  and  for  the  prevention  of  perturbations  due 
to  currents  of  air.  The  beam  is  usually  divided  by  notches 
into  tenths,  so  as  to  carry  weights  shaped  as  riders,  which  latter 
lessen  in  value  as  they  are  moved  toward  the  center.  For  instance, 
a  rider  weighing  i  gram  in  the  pan  weighs  .9  gram  at  the  first 
notch  from  the  pan,  .8  gram  at  the  second,  .7  gram  at  the  third, 
and  .1  gram  at  the  last.  By  this  means  a  delicate  chemical 
balance  will  indicate  with  distinctness  -^  of  a  milligram,  and 
even  less  weights  will  influence  it  sufficiently  to  show  a  variation 
in  the  position  of  the  index  as  it  moves  over  the  graduated  arc. 

Volume. — The  quantity  of  space  which  a  body  fills  is  called 
its  volume  or  bulk.  In  estimating  volume,  vessels  of  different 


METROLOGY  19 

shapes  and  sizes  are  used.  These  vessels,  known  as  measures  of 
capacity,  are  standardized  by  comparison  with  some  unit. 

Weights  and  Measures.— There  are  two  systems  of  weights 
and  measures  in  use  among  physicians  and  pharmacists.  In  the 
United  States  the  prescriptions  usually  call  for  Apothecaries' 
Weights  and  Wine  Measure  with  the  common  standard  of  the 
grain.  Very  rarely  the  decimal  system,  based  upon  the  meter, 
is  employed. 

In  the  U.  S.  Pharmacopoeia  working  formulas  are  given  in 
the  metric  system.  The  regulations  of  the  U.  S.  army  require 
surgeons  to  write  prescriptions  in  the  decimal  system.  In  time, 
as  pharmacists  grow  accustomed  to  the  easy  calculations  of  a 
decimal  system,  it  will  probably  win  favor  enough  to  supplant 
others  now  in  vogue. 

The  U.  S.  Pharmacopoeia  Apothecaries'  system  of  weights  is 
derived  from  the  Troy  pound  of  twelve  ounces. 

TABLE  OF  APOTHECARIES'  WEIGHT 

20  grains  =  gr.  xx  =  one  scruple  OJ). 

60  grains  =  ^iij  (3  scruples)  =  one  dram  (3J). 

480  grains  =  £>vnj  (8  drams)  =  one  ounce  (3]). 

5760  grains  =  ^xij  (12  ounces)  =  one  pound  (Ibj). 

In  the  British  Pharmacopoeia  and  in  commercial  transactions 
of  druggists  in  this  country  the  weights  used  are  the  Avoirdupois 
pound,  ounce,  and  grain. 

If  the  difference  in  the  value  of  the  terms  ounce  and  pound,  as 
used  in  the  United  States  and  in  Great  Britain,  be  not  recognized, 
serious  errors  may  be  committed.  As  important  medical  works 
are  printed  in  both  countries,  addressed  in  the  same  language  to 
readers  in  both,  it  is  to  be  regretted  that  there  should  exist  this 
difference  in  terminology  where  uniformity  and  precision  are 
especially  to  be  desired.  The  special  amount  of  the  Avoirdupois 
ounce  is  usually  indicated  by  a  sign  different  from  that  employed 
in  the  Apothecaries'  system:  Thus  one  oz.  stands  for  437.5  grains; 
while  ^j  means  480  grains. 

TABLE  OF  BRITISH  PHARMACOPCEIA  AVOIRDUPOIS  WEIGHT 

437.5  grains     =     one  ounce  (i  oz.). 
7000     grains     =     16  oz.     =     one  pound  com.  (lib.). 

The  Measures  of  Capacity  employed  in  the  U.  S.  Pharmacopoeia 
are  derived  either  from  the  wine  gallon  or  from  the  metric  system. 

TABLE  OF  WINE  MEASURE  (U.  S.  P.) 

I  minim   =  TTU  =         °-95  grains  of  water. 

60  minims  —  IJyx  =  fsy  (fluidram)  =        55.9        " 

480  minims  -=  ftviij  =  f^j  (fluidounce)  =      455*7        " 

7680  minims  =  V$ xvj  =  Oj  (octarius  or  pint)  —    7291.2        "  " 

61440  minims  =  Oviij  =  cong.  (congius  or  gallon)  =  58328.8        "  " 


20  INTRODUCTION 

Originally  it  was  intended  that  one  minim  of  the  standard 
fluid,  water,  should  weigh  one  grain.  In  fact,  as  stated  in  the 
table,  under  ordinary  conditions  it  weighs  0.95  grains,  while  the 
fluidounce  weighs  only  455.7  grains.  There  is  a  much  wider 
discrepancy  between  the  pint  of  16  fluidounces  and  the  pound  of 
12  Troy  ounces.  In  order  to  make  terms  of  weight  and  measure 
more  easily  convertible  the  British  Pharmacopoeia  uses  a  system 
in  which  the  fluidounce  of  water  weighs  an  Avoirdupois  ounce  of 
437-5  grains.  This  system  is  given  below: 

TABLE  OF  IMPERIAL  MEASURE  (B.  P.) 

1  minim    —  min.  j  0.91  grains  of  water. 

60  minims  =  fl.  dr.  j  =  If^lx  54.68       " 

480  minims  =  fl.  oz.  j  =  f^viij  =         437-5O      "  " 

9600  minims  =  Oj          =  f^xx  =       8750.0x3       "  " 

76800  minims  =  cong.  j  =  Oviij  =     70000.00      "  " 

A  pint  of  water  is  not  a  pound  in  the  Apothecaries'  system,  for 
the  Troy  pound  has  12  ounces,  while  a  Wine  Measure  pint  has  16 
ounces.  But  the  Avoirdupois  or  commercial  pound  is  16  ounces, 
which  is  nearer  the  weight  of  a  pint  of  water,  though  not  exactly 
equivalent.  The  pint  of  water  weighs  7291.2  grains,  though  the 
pound  weight  itself  is  equal  to  only  7000  standard  grains. 
APPROXIMATE  MEASURES 

A  wineglassful    is  equivalent  to  about  2  fluidounces. 
A  tablespoonful  "  "       £  fluidounce. 

A  dessertspoonful  "  "        2  fluidrams. 

A  teaspoonful  "  «'        1  fluidram. 

The  metric  system  has  the  great  advantages  of  a  common  unit 
for  measures  of  weight,  capacity,  length,  and  surface,  thus  per- 
mitting easy  conversion  of  one  into  terms  of  another. 

Not  only  is  measuring  more  easily  done  than  weighing;  it  is 
also,  as  a  rule,  more  accurately  done.  The  facility  in  calculation 
afforded  by  the  metric  system  is  especially  seen  in  the  conversions 
of  volumetric  analysis  which  enable  the  analyst,  by  careful  meas- 
urement, to  dispense  with  the  weighing  of  precipitates.  All  the 
benefits  that  accrue  to  arithmetic  computations  by  a  decimal 
system  of  counting  (now  universal)  is  shared  by  our  American 
division  of  coins,  and  will  be  further  extended  wherever  the  metric 
system  of  weights  and  measures  is  adopted.  The  natural  conser- 
vatism of  the  English  race  has  delayed  its  general  adoption  in 
commerce,  in  medicine,  and  in  pharmacy,  but  in  chemical  and 
physical  calculations  it  is  now  almost  universally  employed. 

Metric  Units.-— The  unit  of  length,  called  a  meter,  is  the  length 
of  a  standard  bar  of  metal  which  was  supposed  to  be  equal  to  one 
ten-millionth  part  of  the  distance  from  the  equator  to  the  pole. 
The  meter  is  really  the  length  of  a  certain  bar  of  platinum  kept  by 
the  Department  of  Weights  and  Measures  in  Paris. 


METROLOGY 


21 


The  unit  of  capacity,  called  a  liter,  is  the  cube  of  a  tenth  part 
of  a  meter. 

The  unit  of  weight,  called  a  gram,  is  the  weight  of  so  much 
distilled  water  at  its  maximum  density  (4°  C.)  as  will  fill  a  cube 
of  the  one-hundredth  part  of  a  meter.  In  taking  this  cubic  centi- 
meter of  water  as  a  unit  of  weight  a  simple  and  very  desirable 
relationship  is  established  between  weights  and  measures. 

The  unit  of  surface,  called  the  are,  is  the  square  of  ten  meters. 


DECIMAL  TABLE 

In  giving  names  to  the  decimal  multiples  a  Greek  numeral  is  prefixed ;  while 
those  of  the  subdivisions  are  formed  from  Latin  words  signifying  the  decimal  fractions. 

Length.  Weight.  Capacity. 

1000  =  kilometer kilogram kiloliter. 

100  =  hectometer hectogram hectoliter. 

10  =  decameter decagram decaliter. 

I  =  Meter Gram Liter. 

.1  =  decimeter decigram deciliter. 

.01  =  centimeter centigram centiliter. 


.001  =  millimeter milligram 


milliliter. 


As  a  rule,  the  terms  used  are  the  kilometer,  kilogram,  kiloliter,  the 
meter,  gram,  liter,  and  the  millimeter,  milligram,  cubic  centimeter,  or 
milliliter. 

MEASURES  OF  LENGTH 

I  meter  =  10  decimeters  =  loo  centimeters  =  1000  millimeters. 
I  meter  =  1.09363  yards  =  3.2809  feet  =  39.3709  inches. 


MEASURES  OF  CAPACITY 

I  cubic  meter  =  looo  liters  =  1,000,000  cubic  centimeters  =  1,000,000,000 
cubic  millimeters. 

I  liter  =  61.02705  cubic  inches  =  .035317  cubic  foot  =  2.1134  pints  =  .22097 
gallon. 

MEASURES  OF  WEIGHT 

I  gram  =  weight  of  I  c.c.  of  water  at  4°  C. 

I  kilogram  =  looo  grams  —  100,000  centigrams  —  1, 000,000  milligrams. 

I  kilogram  =  2.20462  pounds  =  35.2739  ounces  =  15432.35  grains. 


Solids, 
grain 


5  grains 
10       " 

I  scruple  (20  grs.) 
I  dram  Troy  (60  grs.) 
I  ounce  Troy  (480  grs.) 
I  ounce  Avoirdupois  (437.5  grs.) 


Exact  equivalent. 

0.006479  gram. 

0.008098 

0.010798 

0.016200 

0.021599 

0.032399 

0.064798 

0.3230 
.  0.6460 

1.2960 

3.888 
31-103 
28.350 


22  INTRODUCTION 

MEASURES  OF  WEIGHT 

Liquids.  Exact  equivalent. 

I  minim  =  0.06 1  cubic  centimeter. 

I  fluidram  3-697  cubic  centimeters. 

I  fluidounce  =  29.574     " 

4  fluidounces  ($  liter)  =  118.295     " 

8         «  (i    "  )  =  236.590     « 

I  pint  (liter  =      473-l8°     " 

I  quart  .946  liter. 

To  facilitate  mental  translations  from  the  decimal  system  to 
the  one  used  in  this  country,  and  for  rapid  reference,  the  follow- 
ing approximate  equivalents  are  recommended  as  easy  to  mem- 
orize : 

APPROXIMATE  EQUIVALENTS 

meter  3  ^et,  3f  inches. 

kilometer  =  f  mile. 

millimeter  =  ^5-  inch. 

liter  =  2.113  pints  (U.  S.),  or  about  I  quart. 

kilogram  =  2^  pounds,  Avoirdupois. 

gram  15!  grains,  or  about  ^  ounce. 

milligram  Jg  grain. 

are  =  a  square,  the  side  of  which  is  1 1  yards. 

On  the  basis  of  calculating  65  milligrams  to  make  a  grain  and 
32  grams  to  the  ounce,  Troy,  the  following  round  numbers  may 
be  of  service  in  prescription  writing,  being  sufficiently  accurate  for 
that  purpose: 


grain  j 


j  or 

or  5j  =  32 


06  gram  or  cubic  centimeter, 
grams  or  cubic  centimeters. 


The  line  is  used  instead  of  a  decimal  point,  the  figures  standing 
for  solid  grams  or  fluid  cubic  centimeters.  A  teaspoon  holds 
about  5  c.c.  and  a  tablespoon  about  20  c.c. 

The  United  States  nickel  (five-cent  piece)  weighs  5  grams,  and 
is  2  centimeters  in  diameter. 

Specific  Gravity.— If  we  take  equal  volumes  of  different 
substances  we  find  that  there  are  great  variations  in  the  weights. 
If  a  certain  volume  of  hydrogen,  the  lightest  element,  weighs 
i  grain,  the  same  volume  of  air  weighs  14;  of  water,  11,943;  and 
of  osmium,  the  heaviest  element,  267,553.  There  is  a  constant 
and  peculiar  relationship  between  the  weight  and  the  volume 
of  every  natural  substance.  This  relationship  is  called  the  specific 
gravity.  The  specific  gravity  of  a  body  is  its  weight,  as  compared 
with  the  weight  of  an  equal  bulk  of  a  standard  body  taken  as 
unity. 

The  density  of  that  body  is  its  mass  or  quantity,  as  compared 
with  the  mass  of  an  equal  volume  of  a  standard  substance.  By 
the  law  of  gravitation  the  weight  or  gravitative  force  is  directly 


METROLOGY  23 

proportionate  to  the  mass,  hence  no  error  ordinarily  results  from 
the  indifferent  employment  of  the  two  terms.  Sometimes  the 
term  density  is  used  to  signify  the  specific  gravity  of  a  vapor, 
taking  hydrogen  as  a  unit. 

Water  is  so  easily  obtained  in  a  pure  state  that  it  is  chosen  as 
a  standard  for  both  liquids  and  solids;  that  is,  the  latter  are  said 
to  be  so  much  lighter  or  so  much  heavier  than  water.  When  it 
is  said  that  the  specific  gravity  of  urine  is  1020,  it  is  meant  that  a 
bulk  of  urine  equal  to  the  bulk  of  i.o  part  of  water  will  weigh 
1.020  parts.  Likewise  we  say  that  the  specific  gravity  of  a  dry 
gall-stone  is  0.9,  meaning  that  equal  bulks  of  water  and  the  con- 
cretion bear  the  proportion  to  each  other  by  weight  of  i  and  0.9. 

For  specific  gravity  of  solids  heavier  than  water  application 
is  made  of  the  principle  that  a  substance  immersed  in  a  liquid 
displaces  a  bulk  of  that  liquid  equal  to  the  bulk  of  the  body  im- 
mersed. 

The  body  may  be  slowly  submerged  in  the  Water  contained  in 
a  suitable  vessel  filled  to  the  brim.  The  overflow  is  caught  and 
weighed,  and  the  ratio  calculated  as  follows: 

Weight  of  water  :  weight  of  body  :  :  i  :  specific  gravity. 

Thus,  a  piece  of  sulphur  weighing  32  grams  and  held  by  a 
thread  was  very  slowly  immersed  in  a  lipped  vessel  filled  to  the 
brim  with  water.  The  overflow  was  caught  in  a  tared  beaker,  and 
weighed  16.5  grams.  Then — 

16.5  :  32  :  :  i  :  specific  gravity  =  1.9  +  . 

A  more  convenient  and  accurate  method  makes  use  of  the  law: 
"A  solid  immersed  in  a  liquid  loses  a  weight  equal  to  the  weight 
of  an  equal  volume  of  the  liquid."  The  body  is  suspended  by 
a  fine  thread  or  platinum  wire,  and  weighed  in  the  air.  It  is 
next  totally  immersed  in  pure  water  and  its  weight  noted.  By 
subtracting  the  weight  in  water  from  the  weight  in  air  we  obtain 
the  loss  in  weight,  which  represents  the  weight  of  an  equal  bulk 
of  water.  Then — 

Loss  in  water  :  weight  in  air  :  :  i  :  specific  gravity. 

For  example,  weight  of  body  in  air,  9.560  grams, 
weight  in  water,  8.540 
loss  in  weight,  1.02 

Therefore,  1.02  :  9.56  :  :  i  :  specific  gravity  =  9. 37. 


24  INTRODUCTION 

BY  RULE. — Divide  the  weight  in  air  by  the  loss  of  weight  in 
water,  and  the  quotient  is  the  specific  gravity,  with  water  as  the 
unit. 

For  solids  lighter  than  water  and  which  float  of  themselves  it 
is  necessary  to  add  a  sinker,  such  as  a  glass  bead  full  of  mercury, 
or  a  piece  of  lead.  The  body  is  weighed  and  then  attached  to  a 
sinker  which  has  been  previously  weighed  in  air  and  in  water,  and 
its  loss  noted.  The  two  are  weighed  together,  first  in  air  and  then 
in  water,  to  determine  their  joint  loss.  The  joint  loss,  less  the 
loss  of  sinker,  gives  the  loss  of  the  light  body. 

From  this  the  specific  gravity  is  determined,  as  above,  by  divid- 
ing the  weight  of  the  light  body  in  air  by  the  loss  of  weight  in 
water.     For  example:  a  dry  biliary  concretion  floats  on  water;  if 
it  be  sunk  by  attaching  to  it  the  heavy  body  used  in  the  illustra- 
tion of  finding  the  specific  gravity  of  solids  heavier  than  water, 
then- 
Concretion  weighs  in  air,          0.910  grams, 
sinker  weighs  in  air,  9.56 

both  weigh  in  air,  10.47 

both  weigh  in  water,  8.47          " 


both  lose  in  water,  2.00 

sinker  loses  in  water,  1.02 


then  concretion  loses  in  water,   0.98 
and    0.910 -=-0.98  =  0.928  =  specific    gravity    of    concretion. 

For  Powders. — After  noting  the  weight  of  the  powder  (w)  put 
it  in  a  counterpoised  bottle  with  a  mark  of  capacity,  say  50  c.c.  or 
grams.  Fill  the  bottle  to  the  mark  with  pure  water  and  weigh. 
From  the  joint  weight  subtract  the  weight  of  the  powder;  this 
will  give  the  weight  of  the  water,  which,  subtracted  from  the 
known  weight  of  the  water  filling  the  bottle  50  grams,  will  leave 
the  weight  of  a  volume  of  water  equal  to  that  of  the  powder  (w'). 
From  these  factors  the  specific  gravity  is  calculated  by  the  same 
rule-of-three  as  in  previous  cases: 

Weight  of  water  (w')  :  weight  of  body  (w)  :  :  i  :  specific  gravity. 

For  Liquids. — In  the  metric  system  the  weight  of  i  c.c.  of 
water  at  4°  C.  (39.2°  F.)  is  called  i  gram,  therefore,  the  weight 
in  grams  of  i  c.c.  of  a  liquid  is  identical  with  its  specific  gravity. 

When  the  sample  to  be  tested  is  small  in  amount,  a  rapid  com- 
putation can  be  made  by  weighing,  in  grams,  the  liquid  in  a  glass 
pipet  holding  i  c.c.  when  filled  to  the  mark  (Fig.  i).  The  liquid 
is  drawn  up  above  the  scratched  ring  on  the  neck  by  suction  with 


METROLOGY 


the  mouth  or  with  a  rubber  medicine-dropper,  The  excess  is  per- 
mitted to  drop  out  until  the  level  of  the  ring  is  reached.  Then, 
having  detached  the  rubber  tube  and  wiped  the  glass  dry,  the 
pipet  and  contents  are  weighed  in  a  horizontal  position  on  a  wire 


FIG.  i.— Specific  gravity  pipet. 

rack  or  on  the  scale-pan.  A  counterpoise  or  tare  should  be  made 
in  advance,  to  cancel  the  weight  of  the  empty  pipet  and  rack.  As 
stated  above,  the  weight  of  the  liquid  will  be  its  specific  gravity. 
The  process  is  convenient  and  the  liability  of  error  is  less  than 
o.oo i.  When  larger  quantities  are  dealt  with  the  result  is  even 
more  accurate. 

The  weight  of  a  liter  (1000  c.c.)  in  kilograms  (1000  grams),  or  the 
weight  of  50  c.c.  in  grams  multiplied  by  20  (  =  1000  c.c.  in  kilograms) 
is  the  specific  gravity  of  the  liquid.  To  take  the  specific  gravity  by 

this  method  a  pyknometer  (Fig.  2)  or 
sped  fie- gravity  bottle  is  used.  This 
bottle  has  a  narrow  neck  and  may  be 
obtained  small  enough  to  contain  5  or 
50  c.c.,  or  perhaps  fully  1000  grains  of 
water,  or,  in  fact,  any  known  quantity 
capable  of  being  weighed  on  a  delicate 


FIG.  2. — Pyknometer:  A,  Thermometer 
in  neck  of  bottle. 


FIG.  3. — Hydrometer. 


balance.     An  accurate  tare  for  the  empty  bottle  is  placed  in  the 
opposite  scale-pan.     The  bottle  is  filled  to  the  mark  or  perhaps  to 


26  INTRODUCTION 

the  brim  with  the  liquid,  and  wiped  dry  on  the  outside.  It  is  then 
carefully  weighed.  If  it  be  a  looo-grain  bottle  the  weight  in 
grains  will  at  once  stand  for  specific  gravity  with  water  as  1000. 
A  rule-of-three  sum  will  be  needed  if  the  capacity  is  other  than 
1000,  as — 

Known  capacity  :  weight  of  liquid  :  :  i  :  specific  gravity. 

In  careful  observations  it  is  necessary  to  make  allowance 
for  variations  of  temperature,  which  by  expanding  or  contracting 
the  fluid  will  alter  its  specific  relationship  to  an  equal  bulk  of 
water  at  15.5°  C.  (60°  F.),  the  standard  point.  By  the  use  of  ice 
in  a  surrounding  vessel  the  temperature  of  the  fluid  can  be  held 
at  15.5°  C.  (60°  F.)  while  under  examination.  With  simple 
liquids  calculation  with  a  factor  of  error  for  variation  may  be  used. 
For  the  urine  a  rough  allowance  is  made  of  i  degree  of  specific 
gravity  on  the  hydrometer  scale  for  each  3°  C.  (5.4°  F.)  of  tempera- 
ture above  or  below  the  temperature  at  which  the  hydrometer 
or  urinometer  was  standardized.  Thus  the  specific  gravity  of  a 
sample  of  urine  was  1025  when  the  room  temperature  was  21.5°  C. 
(71°  F.)  as  21.5°  is  6°  higher  than  the  standard,  we  must  add 
2  degrees  of  specific  gravity  to  the  1025,  making  1027.  If  the  room 
temperature  was  lower  than  15.5°  C.  the  difference  must  be  sub- 
tracted according  to  the  same  allowance.  On  the  continent  of 
Europe  the  point  of  maximum  density  of  water,  4°  C.  (39.2°),  is 
chosen  for  comparison.  The  tables  of  the  U.  S.  Pharmacopoeia 
are  based  upon  a  standard  temperature  of  25°  C.  (77°  F.)  which 
was  adopted  because  the  average  temperature  of  laboratories 
in  the  United  States  is  77°  F. 

Hydrometer. — Though  not  quite  so  accurate  in  its  results  as 
the  method  by  the  pyknometer,  that  by  the  hydrometer  (Fig.  3) 
has  the  commendations  of  being  very  easy  and  ready,  and  of  dis- 
pensing with  weights  and  balance.  It  is  therefore  commonly 
resorted  to  in  medicine,  pharmacy,  and  the  other  arts.  The 
hydrometer  is  a  spindle-shaped  glass  instrument,  having  a  grad- 
uated stem  above  and  a  weighted  bulb  below,  intended  to  float 
upright  and  measure  the  volume  of  liquid  displaced.  The  zero  of 
the  graduated  scale  is  the  point  (a)  to  which  the  instrument  sinks 
in  pure  water,  and  may  stand  for  1000  or  for  i.ooo.  Degrees 
above  and  below  this  point  indicate  the  specific  gravity  of  the 
liquid,  the  surface  level  of  which  makes  a  line  coinciding  with  the 
mark  (b)  on  the  upright  scale  of  the  floating  instrument.  Special 
scales  are  made  for  use  in  the  arts  by  which  the  strength  of  aqueous 
solutions,  or  the  percentage  of  alcohol  in  various  spirits  may  be 
expeditiously  determined.  These,  according  to  their  purpose, 


METROLOGY  27 

are  styled  lactometer,  urinometer,  sac  char  o  meter,  alcoholometer, 
etc. 

Physicians  frequently  use  the  urinometer  to  determine  the 
amount  of  "solid  urine"  dissolved,  and  also  to  get  a  clue  as  to  the 
presence  of  albumin  or  sugar.  Its  various  applications  are  dis- 
cussed on  pages  569,  583.  The  scale  of  the  urinometer  is  marked 
for  liquids  heavier  than  water,  and  usually  ranges  from  zero  or 
1000  at  the  top  to  60,  meaning  1060,  at  the  bottom.  In  practising 
this  method  the  glass  cylindric  vessel  which  usually  accompanies 
it  should  be  about  two-thirds  full  of  urine  and  the  urinometer 
gently  immersed  to  about  1020  and  then  allowed  to  come  to  a 
stand.  If  the  vessel  has  a  perfectly  flat  rim,  it  may  be  slowly 
filled  to  the  brim  with  urine  and  then  the  reading  made  with  the 
eye  on  a  level.  In  this  way  the  most  trustworthy  register  can  be 
taken. 

For  gases  the  specific  gravity  is  determined  in  the  same  man- 
ner as  for  liquids  by  the  pyknometer.  A  glass  vessel  of  known 
air  capacity  is  exhausted  by  the  air-pump,  counterpoised,  filled 
with  the  gas,  and  weighed.  Air  is  taken  as  a  standard,  and  the 
calculation  for  comparing  the  weights  of  equal  volumes  of  air  and 
gas  is  on  the  same  principle  as  that  given  for  liquids. 

For  vapor  density  a  series  of  very  delicate  operations  is  required, 
which,  while  they  have  no  medical  interest,  yet  are  of  great  im- 
portance in  determining  molecular  weights.  Vapors  are  gases 
that  condense  to  liquids  or  solids  at  ordinary  temperatures.  Ac- 
cording to  the  method  of  Dumas  a  small  glass  flask,  with  a  capillary 
opening  in  its  narrow  neck,  is  first  weighed  full  of  air.  The 
flask  is  then  warmed  and  its  neck  dipped  into  a  fluid,  some  of 
which  enters  as  the  contained  air  cools  and  contracts. 

In  a  bath  of  oil  or  mercury  heated  above  the  boiling-point  the 
substance  vaporizes,  displacing  the  air.  The  neck  is  sealed  with 
the  blowpipe  and  when  cool  weighed.  In  order  to  find  the 
weight  of  the  empty  vessel  the  point  is  broken  with  the  neck  under 
mercury.  The  mercury  rushes  in,  replacing  the  vapor,  and 
filling  the  flask.  By  measuring  this  mercury  the  capacity  of  the 
flask  is  ascertained.  Then  the  weight  of  this  much  air  at  the  same 
temperature  and  barometric  pressure,  subtracted  from  the  original 
weight  of  the  vessel  full  of  air,  gives  the  weight  of  the  empty  flask. 
This  weight,  subtracted  from  the  weight  of  the  flask  full  of  vapor, 
gives  the  weight  of  the  known  volume  of  the  vapor  at  the  tem- 
perature and  atmospheric  pressure  at  which  the  flask  was  sealed. 
Then — Weight  of  air  :  weight  of  vapor  :  :  i  :  vapor  density. 


2$  HEAT 

HEAT 

THERMOMETRY 

THE  temperature  of  substances  involved  in  chemical  reactions 
is  almost  as  important  as  their  weight,  for  the  chemical  properties 
and  behavior  of  bodies  vary  greatly  with  their  temperature.  In 
clinical  observation  of  disease  the  temperature  of  the  patient  should 
never  be  overlooked.  The  presence  or  absence  of  fever  is  always 
noted  most  accurately  by  the  temperature.  Indeed,  it  has  been 
said  that  the  study  of  fever  is  mainly  a  study  of  temperature.  The 
sensation  of  heat  or  cold  imparted  to  the  hand  is  an  unsafe  guide. 
It  depends  upon  the  state  of  the  hand,  and  this  varies  greatly  in 
different  persons  and  at  different  times  in  the  same  person.  The 
hand  may  have  been  chilled  by  recent  immersion  in  cold  water 
or  exposure  to  cold  air,  or  by  temporary  sluggishness  of  the  cir- 
culation of  the  blood.  On  the  contrary,  it  may  be  warmer  than 
usual  by  recent  immersion  in  warm  water,  or  by  the  protection  of 
gloves,  or  by  exposure  to  the  air  of  a  warm  room. 

A  hot  body,  besides  communicating  to  the  observer  the  sensa- 
tion of  heat,  which  is  relative,  imparts  to  other  bodies  in  contact 
or  near  relation  to  it  an  increase  in  size  which  is  constant.  In 
general,  as  bodies  get  hotter  they  expand;  as  they  cool,  they  con- 
tract. This  physical  change  is  objective,  constant,  and  inde- 
pendent of  the  condition  of  the  observer.  By  resort  to  ther- 
mometers measuring  the  degree  of  expansion  we  get  the  standard 
desired. 

The  degree  of  expansion  determines  the  state  oj  aggregation; 
that  is,  whether  it  be  a  solid,  a  liquid,  or  a  vapor.  Water  below 
o°  C.  (32°  F.)  is  solid  (ice);  between  o°  C.  (32°  F.)  and  100°  C. 
(212°  F.)  it  is  liquid;  and  above  100°  C.  (212°  F.)  it  is  a  vapor 
(steam).  By  cold  and  pressure  all  gases  have  been  liquefied  and 
solidified. 

The  molecular  theory  ascribes  this  threefold  state  to  varia- 
tions in  the  range  and  energy  of  motion  of  the  extremely  minute 
particles  of  which  all  bodies  are  composed.  These  particles,  called 
molecules  (little  masses),  are  supposed  to  be  always  in  vibration. 
Their  diameter  has  been  calculated  to  be  between  -%\-$  millionth 
an.d  TOTF  millionth  of  an  inch.  In  a  solid  body,  though  still  in 
agitation,  they  are  supposed  to  be  held  in  a  certain  compact  rela- 
tion to  one  another  by  the  operation  of  an  attractive  force  called 
cohesion. 

Cohesion  is  commonly  defined  as  an  attraction  between  mole- 
cules exerted  at  extremely  small  distances  and  manifested  most 
strongly  in  solids,  less  in  liquids,  and  not  at  all  in  gases.  In 


THERMOMETRY  29 

solids  this  resistance  to  separating  forces  is  very  great  and  its 
phases  are  distinguished  as  hardness,  brittleness,  malleability, 
ductility,  and  tenacity.  The  effect  of  heat  is  to  antagonize  cohesion, 
giving  a  wider  sweep  to  the  motion  of  the  molecules,  thus  causing 
expansion.  This  phenomenon  may  be  shown  with  a  brass  ball 
having  a  close-fitting  ring  gauge.  When  heated  by  a  lamp  it 
is  found  too  large  for  the  gauge,  but  plunged  in  cold  water  it  con- 
tracts and  slips  through  the  ring  easily. 

In  the  liquid  state  the  molecules  are  more  free  to  move,  though 
still  somewhat  under  the  sway  of  cohesion.  A  small  mass  of 
liquid  mercury  rounds  up  into  a  globule  by  virtue  of  this  phe- 
nomenon of  cohesion.  This  same  property  of  holding  together 
enables  one  to  blow  a  soap-bubble  to  a  thin  film.  The  greater 
freedom  of  the  molecules  in  a  liquid  permits  them  to  separate 
further  than  they  do  in  a  solid  by  equal  increments  of  heat.  The 
amount  of  expansion  in  a  solid  is  relatively  small  for  the  ordinary 
range  of  temperature. 

When  heated  from  the  freezing-point  to  the  boiling-point  of 
water,  iron  expands  only  y-J^  °f  ^ts  bulk;  brass  only  3-^;  but 
alcohol  increases  ^-,  water  -^V,  an(^  mercury  -^. 

The  kinetic  theory  is  based  upon  the  observation  that  i  c.c. 
of  a  gas  has  21  trillions  of  molecules.  All  those  of  a  kind  are  alike 
in  weight  and  structure.  Their  weight,  size,  rate  of  motion,  and 
free  path  have  been  mathematically  determined.  In  the  air  at 
o°  C.  (32°  F.)  the  average  speed  is  1591  feet,  in  hydrogen  6050 
feet  per  second. 

The  temperature  is  another  expression  for  the  kinetic  energy 
or  rate  of  motion.  In  a  second  each  hydrogen  molecule  collides 
9480  million  times  with  one  of  its  neighbors,  and  the  two  rebound, 
moving  0.0001855  mm.  before  striking  others.  The  water  vapor 
molecule  has  a  diameter  of  0.00000044  mm.  and  a  free  path  of 
0.00000649  mm. 

This  free  path  gives  the  diameter  of  the  space  between  the 
molecules. 

"If  we  could  see  them  we  should  be  reminded  of  the  dance 
of  a  swarm  of  house-flies  in  the  summer  air,  darting  about,  touch- 
ing one  another,  and  then  sharply  darting  away  in  a  new  direction. 
This  agitation  is  independent  of  winds  or  any  current.  In  calm 
air,  though  all  are  in  motion,  as  many  go  in  any  one  direction  as 
in  any  other,  and  the  effect  is  evenly  balanced.  In  a  wind  more 
molecules  move  in  the  direction  of  the  wind  than  in  any  other. 
The  molecules  are  not  aimed  at  one  another,  and  as  a  collision  is 
all  a  matter  of  chance  the  same  molecule  is  sometimes  nearly 
stopped,  sometimes  hurried,  and  sometimes  merely  deflected.  The 
great  majority,  however,  move  with  about  the  average  speed  of 


30  HEAT 

the  whole  crowd.     Gas  is  a  word  for  a  crowd  of  free  molecules, 
as  nation  is  a  word  for  a  crowd  of  men." 

According  to  this  theory  the  pressure  of  a  gas  or  vapor  'is  the 
cannonade  of  millions  of  molecules  against  the  side  of  the  vessel 
containing  the  gas.  As  the  number  of  impacts  per  square  inch 
and  per  second  is  enormous,  the  effect  is  indistinguishable  from 
that  of  continuous  pressure. 

There  comes  a  point  in  the  expansion  of  a  liquid  when  its  mole- 
cules are  given  such  a  swing  as  to  pass  out  of  the  limited  range 
of  liquid  cohesion  into  the  free  state  of  vapor.  As  stated  above, 
they  are  supposed  now  to  be  in  rapid  and  incessant  motion,  shoot- 
ing about  in  straight  paths  against  one  another  and  creating  a  cer- 
tain pressure  on  the  walls  of  the  containing  vessel.  This  is  known 
as  vapor  tension.  Gases  expand  relatively  far  more  than  do 
solids  or  liquids  by  equal  increments  of  heat.  The  molecular 
activities  of  all  gases  are  so  much  alike  that  they  expand  with 
little  or  no  differences  among  themselves.  Certainly  in  ordinary 
observation  the  rate  of  expansion  of  air,  of  hydrogen,  of  nitrogen, 
of  carbon  dioxid,  and  of  most  other  gases,  is  about  the  same 
(Charles'  or  Gay-Lussac's  law),  being  ^fg-  part  of  their  volume 
at  o°  C.  (32°  F.)  for  every  increase  of  i°  C.  (^-y  for  i°  F.).1  The 
total  expansion  in  being  heated  through  the  100°  C.  (180°  F.) 
from  o°  C.  (32°  F.)  is  more  than  one-third  their  bulk.  For  this 
reason  thermoscopes,  which  measure  the  variations  in  bulk  of  vapors, 
are  extremely  sensitive  and  are  often  used  for  precise  observations  of 
minor  changes  within  a  short  range.  Any  substance  which 
expands  uniformly,  and  whose  alterations  of  volume  under  heat  can 
be  measured,  will  serve  for  a  thermometer.  Mercury  has  advan- 
tages which  commend  it  to  universal  use.  It  can  easily  be  pro- 
cured of  standard  purity;  it  expands  uniformly  and  with  a  rela- 
tively high  rate  for  a  liquid;  it  has  the  conductivity  of  a  metal, 
readily  settling  by  loss  or  gain  to  the  temperature  of  contiguous 
bodies.  It  has  a  range  of  389°  C.  (700°  F.)  between  its  freezing- 
and  its  boiling-point.  Temperatures  below  -  39.4°  C.  (-38.9° 
F.),  the  freezing-point  of  mercury,  are  taken  with  colored  alcohol. 
Above  350°  C.  (662°  F.),  where  mercury  boils,  the  air  pyrometer 
is  used,  and  below  — 240°  C.,  the  thermopile  (p.  32). 

1  Correction  of  Volume  for  Temperature. — The  decimal  corresponding  to  ^ j-g-  is 
0.003665,  which  is  called  the  co-efficient  of  expansion  of  gases.  When  heated  from 
o°  C.  (32°  F.  )  to  i°  C.  (33.8°  F.)  one  volume  of  air  or  of  nitrogen  becomes 
1.003665  volumes;  at  2°  C.  (35.6°  F.)  it  would  be  increased  by  double  the  co-efficient 
(0.003665x2°)  =0.00733.  If  the  temperature  be  above  o°  C.  (32°  F.),  in  order 
to  correct  the  observation  by  reduction  to  the  standard  o°,  the  observed  volume  is 
divided  by  the  factor  [i  +  (o.oo3665Xobserved  temperature)].  Thus,  the  volume 
of  nitrogen  in  an  urea  apparatus  was  60  c.c.,  the  temperature  of  the  room  was  20°  C. 
(68°  F.),  what  would  be  the  volume  at  o°  C.  (32°  F.)  ?  Answer:  i-|-(o.oo3665 
X20°)=i.o733o.  Then  60^-1.0733=55.90  c.c. 


THERMOMETRY 


C. 
100°. 

90  — 
80  — 
70  — 
60  _ 
50  — 
40  _ 
JO  _ 

^o  - 


F. 


—20    —\ 


R. 


—72 


_  /76      _ 


The  Mercurial  Thermometer. — A  thermometer  of  precis- 
ion ought  to  be  made  of  a  selected  tube  which  is  carefully  divided 
into  parts  of  equal  volume  of  the  bore  (Fig.  4).  Two  fixed 
points  are  marked  as  standard: 
the  point  reached  by  the  mer- 
cury when  the  instrument  is 
embedded  in  melting  ice,  the 
jreezing-point  and  another 
point  higher  up  reached  when 
exposed  to  steam  at  average 
atmospheric  pressure,  the  boil- 
ing-point. The  freezing-point 
on  the  Centigrade  scale  is 
marked  zero  (o°);  between  it 
and  the  boiling-point  one  hun- 
dred degrees  are  marked.  On 
Fahrenheit's  scale  the  freezing- 
point  is  called  32°  and  the  boil- 
ing-point 212°,  there  being  180° 
between  them.  In  Reaumur's 
scale  the  freezing-point  is 
marked  o°,  but  the  boiling- 
point  is  80°.  In  English-speak- 
ing countries  both  Centigrade  - /»  I  I /^  — 8  — 

and  Fahrenheit  are  used,  the 
latter  almost  exclusively  by  phys- 
icians, by  the  weather  bureau, 
and  in  the  household.  In 
chemical  circles  in  this  country 
and  in  most  countries  of  Europe  the  Centigrade  is  preferred. 
In  making  the  scales  the  space  covered  by  100°  C.  includes  180° 
F.,  hence  their  relative  values  are  as  i  to  1.8  or  as  5  to  9.  This 
relation  is  complicated  by  the  fact  that  Fahrenheit's  zero  is  not  at 
the  freezing-point,  but  at  thirty-two  of  his  degrees  below  it.  To 
start  from  the  same  point  for  both  we  must  add  or  subtract  32, 
according  to  circumstances.  Briefly  then: 

To  convert  Centigrade  above  o°  to  Fahrenheit,  multiply  by  9 
and  divide  by  5  and  add  32  to  the  product.  To  illustrate:  The 
point  when  water  is  densest  is  4°  C.;  what  is  this  according  to 
Fahrenheit? 


—122      —40 


—  68        —16 


-50 


o 

FIG.  4. — Thermometer  showing  Centigrade, 
Fahrenheit,  and  Reaumur  scales. 


36°-S 


The  formula  for  this  calculation  is  F.  =  |-  C.  +  32. 

To   convert   Fahrenheit   into    Centigrade   degrees   subtract   32, 
multiply  the  remainder  by  5,  and  divide  by  9.     To  illustrate:     The 


HEAT 


normal  temperature  of  the  human  body  is  98.6°  F.,  what  is  this 
on  the  Centigrade  scale? 

98.6°-32°  =  66.6°,     66.6°X5  =  333°,     333°-9  =  37°     C. 

The  formula  for  the  above  is  C.=f  (F.  —  32). 

For  degrees  below  zero  a  similar  calculation  is  used.     Thus, 
mercury  freezes  at  —  39.4°  C.,  what  is  this  reduced  to  Fahrenheit? 

-39-4°Xf=-7°-9°;   and    -7°-9°  +  32°=-38.9°  F- 


The  Absolute  Zero.  —  As  gases  shrink  -5^-3-  of  their  volume 
for  each  degree  of  Centigrade  (^-y  for  i°  F.),  it  is  supposed  that 
at  —  273°  C.  (  —  459.4°  F.)  there  would  be  no  possibility  of  further 
shrinkage  from  loss  of  heat,  and  the  molecules  would  be  at  abso- 
lute rest.  This  is  supposed  to  be  the  temperature  of  interstellar 
space,  and  is  called  the  absolute  zero.  Low  temperatures  are  pro- 
duced artificially;  —258°  C.  (  —  432.4°  F.)  has  been  obtained  by 
allowing  liquid  hydrogen  to  boil  under  diminished  pressure.  At 
this  point,  which  is  15°  C.  (27°  F.)  above  absolute  zero,  the  liquid 
hydrogen  froze.  There  is  but  one  gas  having  a  lower  boiling- 
and  freezing-point  than  hydrogen,  and  that  is  helium,  which 
freezes  at  -268°  C.  (-450.4°  F.)  or  5°  C.  (9°  F.)  above  the 
absolute  zero. 

At  very  low  temperatures  mercury,  alcohol,  and  even  air  are 
frozen;  hence  their  expansion  cannot  be  used  to  measure  varia- 
tions of  the  lowest  temperatures.  The  thermometer  often  used  is 
a  platinum  wire  in  an  electric  circuit  with  a  galvanometer.  As 
the  temperature  falls,  the  resistance  of  the  platinum  falls  also,  and 
the  galvanometer  shows  a  corresponding  increase  of  current- 
strength.  Within  30°  .C.  of  absolute  zero  this  method  is  not 
correct.  For  these  lowest  points  a  thermopile  is  used,  of  silver 
and  platinum,  with  liquid  oxygen  as  a  standard,  and  a  delicate 
galvanometer  to  detect  the  difference.  It  is  believed  to  be  accurate 
down  to  the  melting-point  of  helium,  which  is  5°  or  6°  C.  above 
absolute  zero. 

The  absolute  temperature  is  reckoned  from  the  absolute  zero  by 
adding  273  to  the  Centigrade  reading  and  459  (491  —  32)  to  the 
Fahrenheit.  Thus,  hydrogen  freezes  at  -258°  C.;  therefore 
-258°+  273°=  15°  C.  of  absolute  temperature. 

The  Clinical  Thermometer.—  The  instrument  used  to  note  the 
variations  of  human  temperature  should  not  only  be  correct  in  its 
indications  of  one-fifth  of  a  degree,  but  should  act  quickly  (in 
from  i  to  4  minutes),  should  hold  the  register  at  its  highest  reach, 
even  after  removal  from  the  mouth,  anus,  or  armpit,  and  should 


THERMOMETRY  33 

be  so  constructed  as  easily  to  be  made  aseptic.  Correctness  is 
obtained  by  graduating  after  comparison  with  a  standard  instru- 
ment at  several  nearly  related  temperatures.  Sensitiveness  or 
promptness  of  action  is  produced  by  having  the  smallest  possible 
volume  of  mercury  in  the  bulb  and  a  fine  bore  in  the  indicating 
column.  To  make  this  hair-like  column  visible  it  is  sometimes 
flattened  into  a  ribbon  and  the  glass  shaped  to  act  as  a  lens.  To 
make  an  instrument  self-registering,  various  devices  have  been 
employed  by  which  the  top  of  the  column  is  held  stationary  while 
the  mass  of  the  mercury  is  free  to  contract  within  the  bulb.  The 
principle  in  common  use  is  that  of  constricting  the  tube  at  some 
point,  so  that  the  impediment  will  arrest  the  downward  motion  of 
the  mercury  above  it  and  break  the  column.  In  the  best  form 
of  thermometer  the  mercury  must  pass  by  an  extremely  narrow 
channel  around  the  sharp  corner  of  a  piece  of  glass  sealed  into 
the  bore.  When  warmed  the  expanding  mercury  is  forced  past 
this  obstruction,  but  on  cooling,  the  portion  which  has  been 
driven  above  remains  stationary  while  the  lower  portion  contracts, 
thus  making  a  gap  in  the  column.  This  stationary  portion  indi- 
cates the  maximum  temperature. 

To  set  the  instrument  for  taking  an  observation  the  top  of  this 
detached  column  must  be  lowered  to  the  point  of  35°  C.  (95°  F.). 
This  is  done  by  mechanical  means,  but  jarring  and  striking  the 
instrument  sometimes  causes  it  to  slip  out  of  the  hand,  to  be 
broken  on  the  floor.  Centrifugal  force  serves  us  best  and  is 
brought  into  play  by  holding  the  tube  firmly  with  the  bulb  end 
downward  and  swinging  it  briskly  or  throwing  the  hand  forward 
and  jerking  it  back  quickly,  as  in  cracking  a  whip. 

It  is  necessary  for  accuracy  that  the  instrument  should  not  be 
graduated  until  the  glass  is  seasoned.  The  tube  is  not  always  uni- 
form in  its  caliber.  It  may  be  correct  at  35°  C.  (95°  F.),  but 
incorrect  at  38°  C.  (100.4°  F.). 

On  these  accounts  it  has  become  customary  for  dealers  to 
furnish  certificates  of  correctness  which  attest  accuracy  or  give 
the  factor  of  error  for  several  points  on  the  scale.  For  clinical 
purposes,  where  it  is  frequently  necessary  to  make  an  instrument 
aseptic,  the  glass  tube  with  the  scale  engraved  upon  it  is  to  be 
preferred  to  any  form  using  metal  or  any  other  material.  The 
smooth  and  rounded  surface  is  least  likely  to  harbor  infectious 
germs,  and  it  can  be  easily  sterilized  by  immersion  in  any  anti- 
septic fluid  such  as  formaldehyd,  alcohol,  or  solution  of  cresol. 

The  range  of  human  temperature  being  limited,  the  scale  of  the 

clinical  thermometer  needs  to  be  but  a  few  inches  in  length.     It 

should  register  variations  of  one-fifth  of  a  degree  from  33.3°  C. 

(92°  F.)  to  43.3°  C.  (110°  F.),  and  have  marked  upon  the  glass  the 

3 


34 


HEAT 


minimum  time  of  exposure  required  for  it  to  reach  the  true  tem- 
perature. The  normal  temperature  is  37°  C.  (98.6°  F.).  A 
rise  of  more  than  one  degree  means  that  the  patient  is  feverish. 
Long-continued  temperature  above  40.5°  C.  (105°  F.)  is  dan- 
gerous because  it  induces  widespread  degenerative  changes  in 

the  body. 

CLINICAL  TEMPERATURES 

Above  105.8°  F.  or  41°  C Hyperpyrexia. 

Between  104°  and  105°  F.  or  40°  and  40.5°  C.      ...  High  fever. 

"  102°  and  103°  F.  or  38.8°  and  39.4°  C.  .    .    .  Moderate  fever. 

"  99.5°  and  101.5°  F-  or  37-5°  and  38'6°  C.  .    .    .  Slight  fever. 

Normal  98.6°  F.  or  37°  C Health. 

About  97.7°  F.  or  36.5°  C Subnormal. 

Below  97°  F.  or  36°  C Collapse. 

SPECIFIC  HEAT 

The  thermometer  is  used  to  mark  the  intensity  with  which 
heat  acts,  but  it  is  necessary  to  supplement  its  reading  with  other 
observations  if  we  would  learn  the  quantity  of  heat  engaged.  An 
elevation  of  temperature  of  i°  in  a  given  quantity  of  water  re- 
quires that  a  certain  amount  of  heat  should  be  supplied  to  the 
water;  to  raise  another  equal  mass  of  water  through  i°  requires 
an  equal  amount  of  heat.  It  follows,  therefore,  that  twice  the 
amount  of  water  in  rising  through  i  °  will  absorb  twice  the  amount 
of  heat  as  was  needed  for  the  single  mass.  This  gives  us  a  unit 
for  recording  the  quantity  of  heat — "the  amount  required  to 
raise  one  gram  of  water  one  degree  Centigrade  in  temperature." 
It  is  called  the  gram-degree  unit  of  heat,  or  the  calorie,  and  is  abbre- 
viated col. 

For  stating  large  transfers  of  heat,  as  in  dealing  with  the  fuel  value 
of  foods,  it  is  desirable  to  have  a  large  unit.  The  large  Calorie  (Cat.} 
is  the  amount  of  heat  required  to  raise  one  kilogram  of  water  one 
degree  Centigrade  or  about  i  pound  of  water  4  degrees  Fahrenheit.  It 
is  equal  to  1000  small  calories  (cal.). 

Heat  Capacity. — To  raise  the  temperature  of  equal  masses 
of  different  substances,  such  as  copper,  mercury,  or  lead,  through 
the  same  number  of  degrees,  different  quantities  of  heat  are 
absorbed.  This  heat  reappears  when  the  bodies  return  to  their 
original  temperature.  Each  body  is  thus  shown  to  have  a  differ- 
ent capacity  for  absorbing  heat.  The  thermal  capacity  of  water 
is  the  heat  that  must  be  supplied  to  it  to  raise  one  gram  through 
one  degree  Centigrade. 

In  a  suitable  instrument  known  as  a  calorimeter  the  capacity 
for  heat  of  any  body  can  be  compared  with  that  for  water.  This 
gives  us  the  specific  heat  of  the  body,  which  is  the  ratio  between  its 
heat  capacity  and  that  of  water  taken  as  i.  When  equal  weights 


MELTING    AND    FREEZING  35 

of  mercury  and  water  are  exposed  to  the  same  heat  for  the  same 
period  it  is  found  that  while  the  water  rises  i°  C.,  the  mercury 
will  rise  30°  C.  Therefore,  the  thermal  capacity  of  mercury  is 
•^g-  or  0.0333  that  of  water — that  is,  the  specific  heat  of  mercury 
(water— i)  is  0.0333. 

A  study  of  heat  capacity  is  of  great  importance  to  the  chemist, 
as  it  serves  for  the  calculation  of  atomic  weight.  The  specific 
heat  of  solid  elements  is  inversely  proportional  to  the  atomic 
weight;  hence,  for  solid  elements  the  product  of  the  two  is  a 
constant  quantity.  As  stated  by  Dulong  and  Petit:  "The  solid 
elements  have  the  same  atomic  heat."  The  constant  product 
averages  6.4.  It  follows,  therefore,  that  knowing  the  specific  heat 
of  a  solid,  we  can  determine  the  atomic  weight  by  dividing  6.4  by 
the  specific  heat. 

MELTING  AND  FREEZING 

The  temperature  of  a  solid  rises  by  the  application  of  heat 
until  it  reaches  the  melting-  or  fusing-point,  when  a  physical 
change  occurs,  the  body  becoming  a  liquid.  This  change  depends 
upon  a  play  of  molecular  energy  which  is  definite  for  any  given 
substance  at  a  given  temperature.  It  therefore  takes  place  at  a 
fixed  point  for  each  substance,  and  is  a  constant  characteristic 
for  every  substance  which  is  not  altered  chemically  by  the  action 
of  heat.  No  means  of  identifying  substances  and  testing  their 
purity  is  more  often  used  than  that  of  the  determination  of  the 
melting-point.  When  pure,  a  substance  always  melts  exactly  at 
this  point.  Should  a  part  of  it  melt  at  this  degree  and  the  other 
part  remain  solid  up  to  a  higher  temperature,  thus  rendering  an 
indefinite  report,  it  is  evident  that  we  are  dealing  with  a  mixture 
and  not  the  pure  substance. 

A  sharply  accurate  melting  indicates  great  purity,  for  the  least 
impurity  causes  a  considerable  change  in  the  melting-point.  The 
following  are  the  melting-points  of  a  few  substances:  mercury, 
-39.4°  C.  (-39°  F.);  carbolic  acid,  35°  C.  (95°  F.);  potassium, 
62.5°  C.  (144.5°  F.);  benzoic  acid,  120°  C.  (248°  F.);  salicylic 
acid,  155°  C.  (311°  F.);  tin,  217.8°  C.  (442°  F.). 

Determination  of  the  Melting=point  (Fig.  5).— A  minute 
quantity  of  the  substance  is  placed  in  a  short  capillary  tube  (c) 
closed  at  one  end  and  attached  to  a  thermometer  (d)  by  small 
rubber  bands.  The  thermometer  carrying  the  substance  is 
immersed  in  a  beaker  (a)  containing  a  liquid  having  a  high  boiling- 
point,  like  concentrated  sulphuric  acid.  Heat  is  applied  gradually 
and  the  acid  constantly  stirred  with  a  glass  stirrer  (b)  until  the 
solid  is  seen  to  liquefy.  The  thermometer  reading  is  then  taken 
as  the  melting-point  (m.-p.)  of  the  solid.  Freezing  or  solidification 


HEAT 


of  the  liquid  occurs  at  a  point  practically  identical  with  the  melting 
of  the  same  substance  in  its  solid  state. 

Latent  Heat.—  When  the  amount  of  the  solid  is  considerable, 
much  time  is  consumed  in  melting,  and  the  thermometer  does 
not  rise  during  the  whole  period  of  transition  from  the  solid  to  the 
liquid  states,  although  much  heat  is  being  applied.  The  heat  so 
absorbed  and  unrecorded  by  the  thermometer  is  called  latent; 
because  it  appears  to  be  stored  up  and  hidden,  to  reappear  as 
sensible  or  free  heat  in  equal  amount  when  the  liquid  freezes. 
Strictly  speaking,  it  is  no  longer  that  form  of  molecular  vibration 
recognizable  as  heat,  but  is  the  energy  employed  in  overcoming 

molecular  cohesion  and  in  maintaining 
the  molecules  in  their  new  relative  posi- 
tions. 

The  amount  of  heat  that  disappears 
varies  with  the  material  substance  and 
its  mass.  Like  the  melting-point,  it  is 
definite  and  characteristic  for  each 
individual  substance. 

Latent  heat  of  fusion  is  the  number 
of  calories  (heat  units)  required  to 
change  one  gram  of  a  substance  from 
the  solid  state  to  the  liquid,  the  tem- 
perature remaining  constant. 

If  a  kilogram  of  water  at  o°  C.  is 
mixed  with  an  equal  weight  of  water 
at  100°  C.  there  will  be  two  kilo- 
grams at  50°  C.  If  a  kilogram  of  ice 
at  o°  be  mixed  with  a  kilogram  of 
water  at  100°  C.,  the  melted  mixture 
will  have  a  temperature  of  only  10.4°  C. 
In  this  last  experiment  each  gram 
weight  of  water  at  100°  C.  in  cooling 
to  10.4°  C.  will  have  given  off  100  — 
10.4  =  89.6  calories.  In  losing  this 
89.6  calories  it  has  melted  one  gram 
of  ice  and  warmed  up  the  resulting 
water  10.4°  C.,  which  equals  10.4  calo- 
ries. Subtracting  this  from  the  89.6 
calories  gives  us  89.6  —  10.4  =  79.2  calories.  In  melting  one  gram 
of  ice  at  o°  C.  there  disappeared  or  was  made  latent  enough  heat 
to  raise  the  temperature  of  a  gram  of  water  79.2°  C.  The  mole- 
cules have  used  up  this  energy  in  acquiring  a  freedom  of  move- 
ment among  themselves  not  previously  possible  while  cohesion 
held  them  in  the  stable  position  characteristic  of  solids.  To 


FIG.  5. — Determination  of  melting- 
point. 


MELTING    AND    FREEZING  37 

liquefy  water  requires  79.2  cal.,  a  higher  latent  heat  of  fusion 
than  any  other  liquid.  Acetic  acid  requires  43.7  cal.;  benzine, 
29.1  cal. 

Effect  of  Pressure  on  the  Melting=point.— In  most  cases 
the  change  from  the  solid  state  to  the  liquid  is  attended  by  expan- 
sion. To  this  rule  there  are  exceptions,  such  as  ice,  bismuth,  and 
iron,  which  contract*  on  fusion.  A  body  that  expands  in  fusing 
has  its  melting-point  raised  by  pressure.  The  effect  of  pressure 
is  so  slight  that  a  pressure  of  156  atmospheres  raises  the  melting- 
point  of  spermaceti  only  3°  C.  (5.4°  F.). 

On  the  other  hand,  the  bodies  that  contract  in  fusing  have 
their  melting-point  lowered  by  pressure.  For  instance,  with  ice, 
pressure  makes  the  change  to  water  more  easy.  In  moulding  a 
snowball  pressure  without  heat  will  melt  the  ice  crystals,  because 
the  compressed  snow  has  a  melting-point  lower  than  o°  C.  (32° 
F.).  On  removing  the  pressure  the  ice  grows  hard  again,  uniting 
the  crystals.  This  is  the  phenomenon  termed  regelation.  The 
fusion-point  of  water  is  lowered  only  0.0075°  C-  (0.0135°  F.)  for 
each  atmosphere  of  pressure. 

Reactions  of  the  State  of  Equilibrium.— When  we  have 
made  a  mixture  of  ice  and  water  at  o°  C.  (32°  F.),  in  which  they 
exist  side  by  side  unchanged,  if  we  put  pressure  on  it  the  equi- 
librium is  disturbed.  In  order  to  relieve  the  pressure  the  ice  melts, 
because  liquid  water  occupies  less  space  than  the  solid.  The 
melting-point  of  the  ice  is  lowered,  but,  on  the  other  hand,  the 
pressure  is  reduced.  This  is  an  illustration  of  the  law  of  reaction 
which  holds  for  all  states  of  equilibrium  in  chemistry  and  physics: 
When  a  system  in  equilibrium  under  constraint  shifts  its  equi- 
librium, there  is  a  reaction  which  opposes  and  partially  destroys 
the  constraint.  From  this  it  is  seen  that  an  equilibrium  is  a  more 
or  less  stable  condition  which,  when  disturbed,  tends  to  restore 
itself  by  reversing  the  disturbance  (p.  82). 

Freezing  Mixtures. — Making  a  solution  of  a  solid  causes  a 
lowering  of  temperature.  As  the  melting  of  a  solid  consumes 
heat,  so  does  the  liquefaction  of  a  solid  by  a  solvent.  The  heat 
is  taken  from  the  mass  itself.  This  is  the  principle  involved  in 
the  production  of  artificial  cold,  which  may  be  sufficient  in  cer- 
tain cases  to  produce  a  lowering  in  temperature  of  surrounding 
bodies,  and  thus  act  as  a  freezing  mixture.  The  more  rapid  the 
process  of  liquefaction  the  greater  is  the  degree  of  cold  produced, 
as  there  is  less  time  for  heat  to  be  conducted  from  without.  When 
snow  or  shaved  ice,  two  parts,  is  mixed  with  one  part  of  common 
salt,  it  quickly  liquefies  and  then  dissolves  the  salt,  both  changes 
reducing  the  temperature  of  neighboring  substances  from  o°  C. 
to  —22°  C.  (-7.6°  F.).  A  mixture  of  5  parts  of  potassium 


38  HEAT 

nitrate,  5  of  ammonium  chlorid,  and  19  of  water  lowers  the  tem- 
perature from  10°  C.  (50°  F.)  to  -12°  C.  (10.4°  F.). 

Cryoscopy. — The  freezing-point  of  a  liquid  is  lowered  by 
dissolving  in  it  any  substance,  solid,  liquid,  or  gaseous.  The  salt 
water  of  the  sea  remains  unfrozen  when  the  rivers  flowing  into  it 
are  covered  with  ice.  The  reduction  of  temperature  is  propor- 
tionate to  the  amount  of  dissolved  substance.  Expressed  in 
another  way,  the  lowering  of  the  freezing-point  is  proportionate 
to  the  number  of  molecules  dissolved  in  a  given  volume  (p.  96). 

For  medical  studies  cryoscopy  is  limited  to  the  determination 
of  the  freezing-point  of  organic  fluids,  such  as  urine,  milk,  or 
blood,  by  means  of  which  information  is  obtained  regarding  the 
amount  of  matter  held  in  solution.  It  is  based  on  the  law  oj 
Raoult,  that  a  definite  quantity  of  any  substance  expressed  in 
molecules  (i.  e.,  the  molecular  weight  of  the  substance  in  grams), 
dissolved  in  a  definite  quantity  of  fluid,  lowers  the  freezing-point 
of  the  solvent  by  a  constant  amount.  From  this  it  follows  that 
the  lowering  is  dependent  upon  the  number  of  molecules  in  solution, 
and  not  upon  their  nature,  size,  or  material.  After  dissolving 
in  1000  c.c.  of  water  the  molecular  weight  of  any  substance  in 
grams,  we  find  that  the  freezing-point  of  the  water  is  depressed 
1.87°  C.  (3.35°  F.).  This  is  the  value  of  its  molecular  lowering. 
In  an  aqueous  solution  the  amount  of  depression  in  Centigrade 
degrees  below  the  freezing-point  of  pure  water  is  often  expressed 
by  the  symbol  J,  delta.  The  J  of  normal  blood  is  0.56;  that 
of  normal  urine  varies  from  1.2  to  2.3;  that  of  cows'  milk  is  0.55 
to  0.56,  whether  Pasteurized  or  not.  If  the  freezing-point  of 
a  sample  of  milk  is  —0.52°  C.  (31.06°  F.),  then  it  has  been 
manipulated.  Making  allowance  for  temporary  variations,  due  to 
excessive  consumption  of  water  on  the  one  hand,  or  of  salt  food 
on  the  other,  depression  in  the  freezing-point  of  the  blood  shows 
failure  of  the  kidneys  to  remove  the  effete  substances.  Serious 
disease  of  the  kidneys  may  depress  it  one  degree  below  the  normal. 

For  exact  researches  upon  cryoscopy  the  apparatus  commonly 
used  for  determining  the  melting-point  of  solids  is  not  sufficiently 
precise.  The  instrument  and  elaborate  technic  of  Beckmann  is  best. 

A  special  differential  thermometer  (T),  graduated  into  hun- 
dredths  of  a  degree,  is  inserted  into  a  stout  glass  tube  (A)  one 
inch  in  diameter,  so  that  the  bulb  is  J  of  an  inch  from  the  bottom 
of  the  tube.  Both  of  these  are  fitted,  without  touching,  into  a 
larger  tube  (D),  which  acts  as  an  air-jacket. 

These  are  supported  in  an  upright  position  by  a  cover  (E), 
placed  on  a  glass  jar  of  two-liters  capacity.  This  jar  is  filled  two- 
thirds  with  shaved  ice,  two  parts,  and  salt,  one  part,  which  is  enough 
to  lower  the  temperature  to  the  desired  point,  about  —  5°  C. 


EVAPORATION 


39 


(23°  F.),  taken  on  an  ordinary  thermometer.  The  liquid  to  be 
examined  is  poured  into  (A)  by  the  side  tube  (B),  and  in  sufficient 
quantity  to  cover  the  bulb  of  the  special  thermometer;  then  (A} 
is  placed  into  the  larger  tube  (D),  which  serves  as  a  cool  chamber. 


FIG.  6. — Cryoscopic  apparatus. 

The  liquid  is  stirred  by  the  wire  (C).  In  about  ten  minutes  the 
liquid  becomes  a  thick  slush;  then  the  freezing-point  is  read,  as  dif- 
ferentiated from  that  of  pure  water,  which  has  been  before  deter- 
mined and  recorded.  Duplicate  determinations  may  be  taken  to 
insure  accuracy. 

EVAPORATION 

A  liquid  exposed  to  the  air  dries  up — that  is,  passes  into  the 
state  of  invisible  vapor  or  gas.  This  spontaneous  evaporation 
occurs  slowly  at  all  temperatures,  but  when  the  liquid  is  boiled 
the  process  is  much  more  rapid.  It  has  been  stated  before  that 
the  molecules  of  a  liquid  have  some  freedom  of  motion.  This 
motion  is  sufficient  to  carry  those  that  have  reached  the  free  sur- 


HEAT 


face,  with  some  velocity,  beyond  the  limit  of  the  liquid  into  the  air. 
No  longer  under  the  sway  of  the  cohesive  force  that  held  the 
molecules  in  the  liquid  state,  they  now  move  freely  in  all  directions 
in  straight  paths,  some  striking  others  and  rebounding,  but  all 
tending  outward. 

In  a  confined  space  the  evaporation  appears  to  cease  very  soon, 
but  in  reality  it  continues,  the  movement  being  only  checked,  and 
as  many  rebound  to  the  liquid  as  leave  its  surface.  When  there 
is  an  equilibrium  between  evaporation  and  condensation  the 
air-space  is  said  to  be  saturated  with  vapor. 

If  a  few  drops  of  a  liquid  are  permitted  to  rise  through  the 
mercury  in  a  barometer  tube,  as  soon  as  they  reach  the  surface 
they  evaporate  and  the  mercury  falls.  The  vapor  exerts  a  pressure 
inside,  which  counterbalances  some  of  the  outer  air-pressure 
that  previously  held  the  mercury  at  760  mm.  (30  in.).  This 
pressure  is  due  to  the  bombardment  of  the  molecules  and  is 
called  tension.  More  liquid  will  depress  the  column  still  further, 
but  eventually  some  will  remain  unevaporated  on  top  of  the  mer- 
cury. For  that  temperature  the  pressure  has  reached  its  max- 
imum and  the  space  is  saturated.  At  a  given  temperature  different 
vapors  depress  the  column  to  different  amounts.  At  20°  C. 
(68°  F.)  water  vapor  depresses  the  column  17  mm.  (0.6  in.); 
alcohol  vapor  60  mm.  (3.54  in.);  and  ether  450  mm.  (17.7  in.). 

If  a  barometer  tube  has  its  space  above  the  mercury  saturated 
with  vapor,  and  we  raise  the  temperature  about  the  tube,  it  will 
be  seen  that  as  the  temperature  rises  the  barometer  column  falls, 
showing  increased  vapor  tension.  The  saturation  pressure  rises 
correspondingly  to  the  rise  of  heat.  The  difference  of  height 
between  an  ordinary  barometer  and  one  having  saturated  vapor 
in  its  upper  space  gives  the  vapor  tension  of  water  for  that  tem- 
perature. The  saturation  vapor-pressures  of  water  are  stated  in 
the  table  below: 

Tension  of  Aqueous   Vapor  in  Millimeters  (Regnault) 


Temperature. 

Tension. 

Temperature. 

Tension. 

Temperature. 

Tension. 

C. 

mm. 

C. 

mm. 

C. 

mm. 

0° 

4.6 

11° 

9.8 

21° 

I8.5 

I 

4.9 

12 

10.4 

22 

19.7 

2 

5-3 

13 

II.  I 

23 

20.9 

3 

5-7 

H 

II.9 

24 

22.2 

4 

6.1 

15 

12.7 

25 

23-6 

5 

6.5 

16 

135 

26 

25.0 

6 

7-0 

17 

144 

27 

26.5 

I 

I:! 

18 

!9 

'5-4 

16.3 

28 
29 

28.1 
29.8 

9 

8.5 

20 

17.4 

3° 

31.6 

10 

9-1 

BOILING  41 

If  the  given  space  be  not  a  vacuum,  but  already  occupied  by 
air  or  other  gases  at  the  same  temperature,  the  same  quantity  of 
aqueous  or  other  vapor  will  diffuse  into  it.  The  only  difference 
is  that  vaporization  will  go  on  more  slowly  because  the  liquid 
particles  encounter  resistance  to  their  passage  into  the  space. 
The  highest  pressure  of  the  new  vapor  will  be  the  same  in  the 
occupied  space  as  it  was  in  the  vacuum.  As  each  vapor  exerts 
its  own  pressure  unaffected  by  others  present,  it  follows  that  the 
total  pressure  of  a  mixture  of  vapors  would  be  equal  to  the  sum 
of  all  the  pressures — shown  by  each  separate  vapor  when  con- 
fined singly  to  the  same  space. 

BOILING 

If  the  table  of  tensions  had  been  extended  to  100°  C.  (212°  F.), 
it  would  have  stated  that  the  pressure  at  that  point  exactly  bal- 
anced a  column  of  mercury  760  mm.  or  30  in.  high — that  is, 
it  was  equal  to  the  weight  of  the  atmosphere.  From  this  we 
deduce  the  law:  that  "boiling  of  a  liquid  occurs  at  the  tempera- 
ture which  raises  the  tension  of  its  vapor  to  a  point  equal  to  the 
pressure  of  the  atmosphere."  As  soon  as  the  tension  rises  beyond 
that  point  the  liquid  molecules  are  animated  with  such  energy 
that  those  on  the  surface  line  press  back  the  superincumbent 
air  and  fly  with  great  velocity  into  the  space  above  the  liquid. 
The  molecules  below  the  surface  form  bubbles  of  vapor  which, 
being  specifically  light,  float  up  to  the  surface,  burst,  and  scatter 
their  contents  into  the  air. 

In  consequence  of  the  above  law,  decreasing  the  pressure  on 
a  liquid  enables  it  to  boil  at  a  lower  temperature.  In  the  vacuum 
of  an  air-pump  water  will  boil  at  the  temperature  of  a  living  room. 
On  the  other  hand,  if  the  pressure  be  increased,  the  boiling-point 
rises.  In  a  closed  boiler  water  may  be  heated  far  above  100°  C. 
(212°  F.)  without  boiling,  because  its  vapor  is  confined  and 
presses  back  upon  the  liquid,  obstructing  the  free  passage  of  the 
molecules. 

Boiling=point. — A  pure  liquid  under  the  same  conditions 
of  pressure  always  boils  at  the  same  temperature.  Like  the 
melting-point  of  a  solid,  the  boiling-point  of  a  liquid  is  so  con- 
stant as  to  be  a  test  for  purity.  The  usual  method  of  determina- 
tion is  one  which  immerses  the  thermometer  in  the  vapor  of  the 
boiling  liquid  just  above  the  surface  of  the  liquid.  The  liquid 
is  put  in  a  flask  (A,  Fig.  7),  having  a  side  tube  in  the  neck  (B) 
for  the  escape  of  vapor.  Through  the  perforated  stopper  passes 
a  thermometer,  which,  when  boiling  begins,  is  surrounded  by  the 
vapor.  The  heat  is  applied  gradually  until  the  liquid  boils.  As 
soon  as  the  mercury  of  the  thermometer  remains  constant  the 


HEAT 


boiling-point  is  read  off.     For  observations  of  extraordinary  del- 
icacy the  instrument    and    technique  of  Beckmann  are  used,  as 

described  on  p.  369. 

Very  different  temperatures  are  re- 
quired to  boil  different  liquids.  While 
water  boils  at  100°  C.  (212°  F.),  mer- 
cury requires  357°  C.  (675°  F.),  abso- 
lute alcohol,  78°  C.  (173°  F.),  pure 
ether,  35°  C.  (95°  F.),  chloroform,  61° 
C.  (142°  F.),  oxygen  the  very  low  point 
-180°  C.  (  —  292°  F.),  and  hydrogen 
still  lower,  -252°  C.  (-422°  F.). 

When  a  solid  is  dissolved  in  a  liquid 
the  boiling-point  rises  correspondingly 
with  the  concentration.  Salts  dis- 
solved in  water  prevent  its  boiling  at 
100°  C.  (212°  F.).  The  molecules  of 
the  dissolved  solid,  in  proportion  to 
their  number,  impede  the  escape  of  those 
of  the  liquid  (p.  369).  The  diminished 
pressure  of  the  atmosphere  in  high 
altitudes  permits  boiling  to  occur  at  a 
point  too  low  for  cooking  in  the  boiler. 
By  adding  kitchen  salt  the  boiling- 
point  is  raised  sufficiently  to  cook  the 
food,  the  effect  of  the  altitude  being 
canceled  by  the  salt. 
Latent  Heat  of  Vaporization.— The  spontaneous  conver- 
sion of  a  liquid  into  a  vapor  is  accomplished  by  absorbing  heat 
from  surrounding  objects.  They  lose  heat,  hence  it  is  said  that 
evaporation  is  a  cooling  process.  Wet  clothes  chill  the  wearer 
because  of  the  evaporation  of  the  water  outside.  Ether  evap- 
orates so  rapidly  when  applied  to  the  skin  as  to  benumb  the  local 
sensibility  through  the  effect  of  the  cold  produced.  The  absorp- 
tion of  heat  is  required  to  overcome  the  cohesion  of  the  liquid 
and  to  impart  to  the  particles  the  velocity  characteristic  of  vapors. 
During  the  whole  time  of  boiling  away  a  liquid  its  temperature 
never  rises  above  its  boiling-point;  all  the  heat  not  sensible  to 
the  thermometer  is  taken  up  in  causing  the  change  of  molecular 
condition,  and  is  called  the  latent  heat  of  the  vapor.  The  exact 
amount  of  heat  that  disappears  is  evolved  again  when  the  vapor 
is  condensed.  Different  liquids  require  different  amounts  of  heat 
to  vaporize  them.  The  latent  heat  of  steam  is  determined  in  the 
following  manner: 

A  kilogram  of  water  at  o°  C.  is  heated  to  100°  C.  by  passing 


FIG.  7. — Apparatus  for  determining 
boiling-point. 


BOILING  43 

steam  into  it.  The  water  now  weighs  1.186  kg. — that  is,  to  raise 
i  kg.  100°  C.,  0.186  kg.  of  steam  have  been  condensed.  If  0.186 
kg.  of  steam  will  raise  i  kg.  of  water  100°  C.,  then  i  kg.  of  steam 
will  raise  5.37  kg.  of  water  100°  C.  or  537  kg.  through  i°  C. 
Steam  then  has  a  latent  heat  of  537  calories,  which  is  the  highest 
of  all  vapors. 

Supercooled  and  Superheated  Water.— The  exact  relationship 
stated  between  the  vaporous  form  and  temperature  and  pressure 
does  not  obtain  unless  both  the  vapor  and  the  liquid  are  present 
simultaneously.  This  appears  on  consideration  of  the  following 
facts:  Many  substances  in  the  liquid  state  can  be  cooled  below 
their  melting-point  without  change  to  the  solid  state.  If  air  is 
excluded  from  the  containing  vessel,  water  can  be  lowered  in 
temperature  10  degrees  below  o°  C.  without  freezing,  though  the 
peculiarity  of  expanding  is  retained.  If  supercooled  only  a  few 
degrees  it  retains  the  liquid  state  indefinitely.  At  the  touch  of  a 
piece  of  ready-formed  ice  it  solidifies  instantly,  the  temperature 
of  the  mass  rising  to  the  freezing-point  —  o°  C.  (32°  F.).  In  this 
supercooled  condition,  ready  to  solidify  by  contact  of  ice,  water 
is  said  to  be  metastable. 

Suspended  Boiling. — In  like  manner  when  dissolved  gases 
have  been  removed  by  previously  boiling  a  liquid  it  may  be  heated 
several  degrees  above  its  boiling-point  without  ebullition  super- 
vening. After  water  has  been  boiled  some  time  in  a  perfectly 
clean  vessel  the  phenomenon  of  bumping  occurs.  The  dissolved 
air  has  been  expelled  by  the  first  boiling,  and  the  temperature  can 
be  raised  several  degrees  above  100°  C.  (212°  F.)  without  changing 
the  state  of  the  water,  until  at  last  one  bubble  of  vapor  disturbs 
the  inertia,  and  a  large  evolution  of  vapor  begins  with  sudden 
explosions.  The  water  heated  above  its  boiling-point  is  said 
"o  be  superheated.  This  is  one  of  the  causes  of  boiler  explosions. 

Supercooled  Vapor. — By  excluding  liquid  water,  aqueous  vapor 
may  retain  its  state  even  when  the  temperature  is  reduced  below 
the  point  of  condensation,  and  the  vapor  subjected  to  pressure 
greater  than  suffices  for  condensation  ordinarily.  When  a  re- 
ceiver containing  air  and  water  is  exhausted  by  the  air-pump,  the 
temperature  declines  and  aqueous  vapor  is  condensed  like  a  fog. 
The  same  experiment  performed  after  twenty-four  hours  of  stand- 
ing shows  no  mist.  The  particles  floating  in  the  air  of  the  receiver 
have  settled  down  and  the  supercooled  vapor  finds  no  points  around 
which  to  condense. 

Equilibrium  of  Three  Phases.— There  is  some  pressure 
or  vapor  tension  caused  by  evaporation  from  ice,  though  it  is  but 
little;  that  from  water  is  greater,  that  of  warm  vapor  greatest,  of 
the  three  forms.  If  accurate  observations  of  these  tensions  be 
recorded  by  measured  lines — upright  ones  for  pressure  and  hori- 


44 


HEAT 


zontal  ones  for  temperature — then  curves  drawn  through  the  meet- 
ing points  give  the  diagram  (Fig.  8)  for  a  system  in  which  the  three 
phases — ice,  water,  and  vapor — exist  side  by  side.  Chemical  as 
well  as  physical  reactions  are  not  completed  in  any  one  direction, 
as  might  be  inferred  from  the  usual  chemical  equation,  but  if  the 
products  are  confined,  having  reached  a  certain  point  short  of 
completion,  the  products  stand  at  an  equilibrium  like  that  of  water. 
There  is  but  one  component  of  the  system  ice-water-vapor,  which 
is  the  chemical  substance  water.  The  vapor  pressure  and  tempera- 
ture-curves of  water  are  shown  in  the  diagram  (Fig.  8).  The  upright 
line  (p)  represents  the  height  of  pressure  of  water-vapor  and  the 
horizontal  line  (/)  the  temperature. 

By  experiment  we  learn  that  the  temperature-pressure  condi- 
tions of  equilibrium  between  ice,  water,  and  aqueous  vapor  can 
be  represented  in  the  curves  radiating  from  O. 

These  diagrammatic  curves  (OA,  OB,  and  OC)  form  the  bound- 
aries of  three  areas,  7,  77,  777.  The  component  water  exists  as 
the  phase  solid  (ice)  at  any  point  of  pressure  and  temperature 
included  in  area  7;  as  liquid  in  area  77;  as  vapor  in  area  777. 
In  these  different  areas  there  is  a  stable  region  for  the  phase 
common  to  the  two  curves  bounding  it.  When  supercooled 

water  is  in  a  state  of  suspended 
solidification,  this  condition  of 
metastable  equilibrium  is  repre- 
sented by  the  curve  OA'. 

The  Triple  Point.— Experi- 
ment shows  that  when  the  pres- 
sure is  about  4.6  mm.  mercury 
and  the  temperature  about  o°  C. 
(32°  F.),  the  three  phases  are  in 
equilibrium;  hence  this  point  is 
called  triple  point.  In  the  dia- 
— *  gram  the  curves  intersect  at  this 

FIG.  8.— Temperature-pressure  diagram  of          point,    O,    where   the   three   phases 

having  the  same  temperature  and 

pressure  exist  side  by  side.  Any  change  in  pressure  or  tempera- 
ture causes  the  disappearance  of  one  phase.  Increase  the  pressure 
and  the  vapor  condenses  to  water,  lower  it  and  the  water  vaporizes. 
Raise  the  temperature  and  the  ice  liquefies,  lower  it  and  the  water 
solidifies.  In  Fig.  8  the  three  curves  run  out  from  O  to  definite 
points  well  within  the  limits  of  the  diagram.  Thus,  the  abrupt 
terminal,  A, .expresses  the  well-known  fact  that  there  is  a  critical 
temperature,  above  which  water  can  no  longer  exist  as  liquid. 
This  extremity  of  OA  shows  also  the  critical  pressure  at  which  the 
two  phases,  water  and  vapor,  disappear  in  the  one  phase — vapor. 


4-6 


THE    GALVANIC    CURRENT 


45 


MAGNETISM  AND  ELECTRICITY 

THE  GALVANIC  CURRENT 

Lodestone  or  leadstone  is  the  name  applied  to  a  piece  of  magnetic 
iron  oxid,  Fe3O4,  because  when  suspended  it  leads  or  points  to 
the  poles  of  the  earth.  This  natural  magnet  attracts  iron,  and  if 
rubbed  on  steel  bars  or  needles  imparts  to  them  its  property  of 
pointing  north  and  south.  The  end  that  points  north  is  called 
the  south  pole  of  the  magnet,  and  that  which  points  south,  the 
north  pole  of  the  magnet.  Such  a  magnet,  dipped  into  iron 
filings,  will  carry  away  at  its  polar  ends  a  quantity  of  the  filings, 
bristling  like  a  brush.  If  the  north  pole  of  one  magnet  be  brought 
near  to  the  north  pole  of  another  that  is  freely  suspended,  the 
latter  will  move  away.  The  south  pole,  however,  will  be  drawn 
to  it.  In  the  same  way  the  south  pole  repels  the  south  pole,  but 
attracts  the  north. 

The  law  of  magnetic  poles  is  that  like  poles  repel,  and  unlike 
poles  attract. 

The  earth  is  a  great  magnet,  having  a  field  of  influence  cover- 
ing its  entire  surface,  so  that  a  magnetic  compass  at  any  place 
will  show  by  its  direction  the  situation  of  the  poles  that  attract  it. 

The  Galvanic  Cell. — If  plates  of  two  dissimilar  substances, 
like  copper  and  zinc,  or  carbon  and  zinc,  are  immersed  in  an  acid 
or  other  fluid  which  corrodes 
one  of  them,  at  the  outside 
ends  there  will  appear  manifes- 
tations of  energy.  If  the  ends 
of  the  plates  are  connected  by 
a  wire,  a  succession  of  effects 
will  be  observed  as  though  a 
continuous  current  of  electric 
force  was  flowing  through  it. 
For  instance:  A  magnetic  needle 
placed  near  the  plates  tends  to 
take  a  position  at  right  angles 
to  them  just  as  long  as  they  are 
connected  by  the  wire,  but  no 

longer.  If  a  solution  be  made  a  part  of  the  circuit  by  immersing 
the  ends  of  the  wires,  then  chemical  decomposition  ensues.  Chem- 
ical action  upon  the  zinc  plate  transmits  electricity  from  that  plate 
through  the  liquid  to  the  other  plate  which  is  not  corroded,  thereby 
generating  a  state  of  energy.  It  is  similar  to  raising  the  level  of 
a  reservoir  of  water  connected  by  a  pipe  with  another  one  on  a 
lower  level.  This  phenomenon  is  called  a  difference  oj  potential 


FIG.  9. — Voltaic  cell  of  copper  (Cu)  and 
zinc  (Zn)  immersed  in  sulphuric  acid,  showing 
direction  of  the  current. 


46  MAGNETISM    AND    ELECTRICITY 

between  the  plates  which,  when  the  wire  outside  connects  them, 
becomes  a  current  capable  of  manifesting  active  energy,  just  as 
the  stream  flowing  from  a  higher  to  a  lower  level  may  do  many 
kinds  of  work  on  the  way. 

As  the  action  on  the  zinc  plate  originates  the  current,  that 
plate' has  the  higher  potential.  It  is  called  positive,  +  ;  but  the  out- 
side end  or  wire,  called  its  pole,  is  electrically  opposite  and  is  said 
to  be  negative,  — .  The  other  plate  (copper,  carbon,  or  other 
substance)  of  lower  potential  is  negative,  — ;  and  its  pole  is  posi- 
tive, + . 

The  power  that  initiates  this  transfer  of  electricity  or  difference 
of  potential  is  called  electromotive  force  (E.  M.  F.).  As  a  differ- 
ence of  level  in  a  water-system  causes  a  corresponding  pressure, 
so  a  difference  of  potential  causes  pressure  or  voltage  in  proportion 
to  that  difference.  According  to  the  electronic  theory,  a  body 
excited  by  negative  electricity  is  considered  to  have  a  charge  of 
excessively  minute  electrons  detached  from  the  molecules  by 
chemical  or  physical  action.  A  body  is  positively  electrified 
when  it  has  lost  electrons,  and  negatively  electrified  when  it 
has  gained  them.  The  gain  in  electrons  at  the  excited  zinc  end 
of  a  battery  starts  a  transfer  of  them  through  the  cell  to  the  carbon 
end,  which  is  relatively  deficient.  This  movement  of  electrons 
along  the  conductor,  from  one  molecule  to  the  next,  is  something 
like  the  "handing  on"  of  water  by  a  line  of  bucket  holders  from 
the  well  or  pond  to  a  house  afire. 

The  outer  polar  wires,  being  the  means  for  the  transmission  of 
the  current,  are  called  electrodes.  The  positive  pole  of  the  copper 
plate  is  termed  the  anode  from  the  greek  prefix  an-,  up,  the  current 
moving  from  it  up  stream;  while  the  negative  pole  coming  from 
the  zinc  plate  bears  the  name  cathode,  from  the  prefix  cath-,  down, 
the  current  moving  to  it  down-stream.  When  the  connections 
outside  are  continuous  the  circuit  is  closed;  if  they  are  broken, 
it  is  open.  When  the  current  is  interrupted  intentionally  it  is  said 
to  be  made  and  broken.  Copper  wire  is  commonly  used  for  con- 
nection because,  like  all  metals,  it  is  a  good  conductor.  The  glass 
of  the  cell  prevents  the  current  passing  out  by  the  bottom  or 
sides  because  glass  is  an  insulator  or  non-conductor,  like  dry 
wood,  vulcanite,  mica,  and  asbestos.  Even  the  best  conductors 
offer  some  resistance  to  the  current,  as  does  a  conduit  to  the  stream 
flowing  through  it. 

To  overcome  resistance  the  impelling  force  must  be  increased. 
In  the  cell  this  is  done  by  choosing  two  plates  of  high  difference 
of  potential.  Carbon  and  zinc,  when  coupled,  have  a  higher 
relative  intensity  than  copper  and  zinc,  which  soon  lose  what 
little  they  had  at  the  start.  Close  examination  of  the  copper 


THE    GALVANIC    CURRENT 


47 


plate  shows  that  bubbles  of  hydrogen  collect  on  it,  converting 
the  surface  into  one  of  hydrogen  and  not  of  copper. 


Zn 

Zinc. 


H2S04 

Sulphuric  acid. 


ZnS04 

Zinc  sulphate. 


H2 

Free  hydrogen. 


The  difference  of  potential  is  lowered,  unless  the  hydrogen  is 
removed  as  fast  as  it  forms.  This  is  accomplished  in  a  different 
way  in  each  of  the  various  cells  that  have  been  devised,  such  as 
Daniell's,  Bunsen's,  Groves',  the  silver  chlorid,  and  the  dry  cells. 
The  two  cells  most  frequently  used  in  laboratories  and  by  phys- 
icians are  the  bichromate  and  the  Leclanche*. 

The  bichromate  (or  Grenet)  cell  is  composed  of  carbon  and 
zinc,  excited  by  a  fluid  made  by  dissolving 
two  ounces  of  potassium  bichromate  in  a  pint 
of  hot  water,  and  adding,  when  cold,  two 
drams  of  mercury  bisulphate  and  three  fluid- 
ounces  of  commercial  sulphuric  acid.  It 
furnishes  a  great  quantity  of  current  in  little 
space  and  can  be  arranged  so  that  the  zincs 
may  be  plunged  into  the  acid  as  the  electricity 
is  required.  The  carbon  is  indestructible. 

This  solution  forms  a  compound  with  the 
hydrogen,  preventing  the  coating  on  the  car- 
bon plate  which  polarizes  it. 

The  Leclanche  cell  has  several  modifica- 
tions, one  of  which  is  called  the  carbon-cyl- 
inder open-circuit  battery.  In  each  there  is  a 
zinc  rod  coupled  with  a  compressed  cylinder 
of  carbon  and  manganese  dioxid.  The  ex- 
citing fluid  is  ammonium  chlorid,  which  acts 
on  the  zinc,  forming  a  zinc-ammonium 
chlorid,  while  the  hydrogen  is  oxidized  and 

removed  by  the  manganese  dioxid.  This  battery,  though  not  well 
adapted  for  continuous  work  because  it  polarizes  rapidly,  is  of 
use  for  short  periods  intermittently.  It  quickly  regains  its  strength; 
when  left  to  itself  it  is  rapidly  depolarized,  and  thus  maintains  its 
intermittent  powers  for  a  long  time  without  needing  attention. 
The  electromotive  force  from  one  cell  is  1.5  volts  only,  but  it  can 
be  raised  to  a  higher  degree  by  linking  a  number  of  cells  in  a  series 
— the  carbon  of  one  connected  with  the  zinc  of  the  next. 

A  combination  or  battery  of  six  cells  has  six  times  the  E.  M.  F. 
of  one  cell,  though  there  is  an  increase  of  internal  resistance  of 
0.7  of  an  ohm  for  each  cell. 

Dry  Cells. — The  principle  of  the  Leclanche*  cell  is  used  in  the 
construction  of  the  ordinary  dry  cell,  which  has  about  the  same 


FIG.  10. — Grenet  cell  of 
carbon  and  zinc  in  bichro- 
mate fluid. 


MAGNETISM    AND    ELECTRICITY 


voltage,  but  an  internal  resistance  of  0.54  of  an  ohm.  Instead 
of  a  glass  cell,  one  of  zinc  is  used,  its  internal  surface  being  the 
positive  plate;  the  external  surface  is  varnished.  In  this  cell  is  a 


FIG.  ii. — Disque  Leclanche  cell. 


FIG.  12. — Carbon-cylinder  battery. 


pasty  mixture  of  ammonium  chlorid,  plaster,  and  zinc  chlorid.  In 
the  center  is  the  carbon  plate  surrounded  by  granulated  carbon 
and  manganese  dioxid,  with  a  porous  septum  separating  them 
from  the  ammonium  chlorid.  Just  enough  water  is  added  barely 


FIG.  13. — Plunge  battery  of  carbon  and  zinc. 

to  moisten  the  granulated  carbon,  and  the  top  is  then  hermetically 
sealed  with  wax.  The  plaster  hardens  and  makes  a  compact, 
almost  unbreakable  mass,  safely  portable  because  there  is  no 
glass  to  break  nor  liquid  to  spill. 


THE    GALVANIC    CURRENT 


49 


The  units    for   measurement  of  electricity  are  named  after 
the  most  celebrated  workers  in  this  field.     They  are  based  upon 
the  observed  analogy  of  the  electric  substance  to  a  fluid  flowing 
invisibly  as  a  current  from  a  reservoir  which 
creates  pressure  according  to  its  height,  through 
conduits  which   discharge   it  into   various  ma- 
chines for    doing  work    like    water    lead    to    a 
turbine  or  mill-wheel.     The  amount   of  work 
(Watt)  depends  on  the  quantity  of  electricity 
passing  in  a  second  of  time  (Ampere)  and  also 
on  the  pressure  driving  the  current  (Volt). 

Ampere :  the  unit  of  current-strength  pro- 
duced by  the  difference  of  potential  of  a  volt 
through  the  resistance  of  an  ohm.  In  order 
that  a  current  of  one  ampere  shall  liberate 
i.oi  gm.  of  hydrogen  it  must  flow  for  96.540 
seconds  through  the  electrolyte. 

Milliampere :   the    thousandth   part    of   an 
ampere,    of   which  from  i  to  100  or  more  may      FIG.  14.— Dry  battery. 
be  administered   to  a  patient  for  medical  purposes. 

Coulomb :  the  unit  of  quantity  conveyed  by  the  current  of  an 
ampere  in  a  second.  For  the  evolution  of  i.oi  gm.  of  hydrogen 
by  electrolysis  96.540  coulombs  must  pass  through  the  electro- 
lyte. 


FIG.  15.— Electrolysis  of  water:    Two  volumes  of  hydrogen  at  the  negative  pole  and  one  volume  of 
oxygen  at  the  positive  pole. 

Farad:  the  unit  of  electric  capacity;  the  quantity  which,  with 
the  electromotive  force  of  a  volt,  would  flow  through  the  resist- 
ance of  an  ohm  in  one  second. 

Ohm :  the  unit  of  resistance  offered  to  a  current  of  electricity 
by  a  wire  of  pure  silver  or  copper  one  millimeter  in  diameter  and 
4 


ijO  MAGNETISM    AND    ELECTRICITY 

48.61    meters  long  at   18.3°  C.  (65°  F.).     The  resistance  of  the 
Atlantic  cable  is  700  ohms. 

Volt:  the  unit  of  electromotive  force.  It  equals  .9268  of  the 
force  of  one  Daniell  cell,  or  .5  the  power  of  a  Grenet  cell,  or  .75 
the  power  of  a  Leclanche  cell. 

Watt :  the  unit  of  electric  power  exerted  when  the  current 
has  the  strength  of  one  ampere  and  the  electromotive  force  of 
one  volt.  Equal  to  TJ¥  of  a  horse  power. 

It  has  been  stated  above  that  the  current  flowing  through  con- 
nected polar  wires  has  magnetic  properties.  The  deviation  of  a 
magnetic  needle  caused  by  it  is  increased  by  encircling  the  needle 
a  number  of  turns  of  the  insulated  conducting  wire.  In  the 
milliampere-meter,  or  milam-meter,  such  a  needle  moves  over  a 
graduated  arc,  the  degrees  indicated  corresponding  to  the  current- 
.strength.  In  medical  practice  from  i  to  100  or  more  milliam- 
peres  are  employed,  according  to  the  needs  of  the  case. 

To  lower  the  current-strength,  the  number  of  cells  thrown  into 
the  circuit  is  diminished  by  a  switchboard,  or  the  battery  remaining 
the  same,  resisting  material  is  introduced  in  the  length  of  the 
conductor.  A  rheostat  is  an  apparatus  for  varying  and  controlling 
the  current-strength  by  adjusting  the  resistance.  It  may  be  made 
of  coils  of  iron  or  German  silver  wire,  or  intercalations  of  carbon 
or  water  may  be  used,  all  of  these  being  poorer  conductors  than 
the  copper  wire. 

Besides  the  magnetic  effects,  the  current  has  physical  powers 
familiar  in  the  electric  lights,  heaters,  and  motors. 

Joule:  this  unit  of  work  energy  equals  0.239  calories  heat 
energy,  the  power  required  to  raise  the  potential  of  one  coulomb 
one  volt.  To  raise  one  pound  one  foot  high  requires  1.326  joules. 

Kilo-joule :  one  thousand  joules. 

Chemical  Effects  of  the  Current.— The  passage  of  elec- 
tricity through  acidulated  water  is  attended  by  the  chemical 
decomposition  of  the  water  iftto  its  elements,  hydrogen  and  oxy- 
gen. This  is  electrolysis,  and  acidulated  water  is  called  an  electro- 
lyte. If  a  solution  of  copper  sulphate  (CuSO4)  be  put  into  the 
electrolytic  cell  and  the  current  sent  through  it  by  platinum  elec- 
trodes, the  salt  is  broken  up  into  its  ions — copper  (Cu)  and  the 
group  (SO4).  Metallic  copper  comes  to  the  negative  pole,  or 
cathode,  just  as  did  the  hydrogen  of  the  water;  hence  the  metals 
and  hydrogen  are  known  as  cations.  The  group  (SO4)  engages 
in  a  second  chemical  action  upon  the  water  of  the  solution,  decom- 
posing the  water  and  setting  free  the  oxygen,  which  bubbles 
off  at  the  positive  pole  or  anode,  and  hence  is  called  the  anion. 
SO4  +  H2O  =  H2SO4  +  O 

Water.  Acid  sulphuric.          Oxygen. 


THE    GALVANIC    CURRENT  51 

When  a  solution  of  sodium  sulphate  (Na2SO4)  is  the  electrolyte, 
the  first  separation  is  into  the  cation,  sodium  (Na)  and  the  anion 
(SO4).  The  metal  sodium  at  once  acts  on  the  water  present, 
producing  sodium  hydroxid  and  liberating  hydrogen,  which 
escapes  at  the  cathode — 

Na2     +      2H20     =     2NaOH     +      H2. 

In  this  case  also  there  is  a  secondary  decomposition  of  the 
water  by  the  SO4  taking  the  H2  and  freeing  the  oxygen  (Fig.  15). 

All  acids,  bases,  and  salts  which  dissolve  and  make  good  con- 
ductors are  electrolytes  and  are  decomposable.  Many  salts 
liquefied  by  fusion,  such  as  the  fused  chlorids  and  hydroxids  of 
various  metals,  are  split  by  the  current.  In  all  such  cases  the 
metal,  like  the  hydrogen  ion,  wanders  to  the  cathode,  and  the 
other  constituent  or  ion — the  non-metal — goes  to  the  anode. 
Below  is  a  list  of  some  of  the  elements  arranged  in  a  U-shape  so 
as  to  show  their  electric  relations.  Any  element  enumerated  is 
found  to  act  as  electronegative  to  those  following  it,  and  electro- 
positive to  those  named  before.  Speaking  generally,  those  be- 
tween hydrogen  and  the  negative  end  are  called  electronegative, 
and  form  anions;  those  toward  the  positive  end  are  electropositive, 
and  form  cations. 

Negative  end.  Positive  end. 

Oxygen.  Potassium. 

Sulphur.  Sodium. 

Nitrogen.  Lithium. 

Fluorin.  Barium. 

Chlorin.  Strontium.  ' 

Bromin.  Calcium, 

lodin.  Magnesium. 

Selenium.  Aluminum. 

Phosphorus.  Manganese. 

Arsenic.  Zinc. 

Chromium.  Iron. 

Vanadium.  Nickel. 

Molybdenum.  Lead. 

Tungsten.  Tin. 

Boron.  Bismuth. 

Carbon.  Copper. 

Antimony.  Silver. 
Tellurium.                                 Mercury. 
Tantalum.                     Platinum. 
Silicon.          Gold. 
Hydrogen. 


52 


MAGNETISM    AND    ELECTRICITY 


Electrolysis  is  subject  to  certain  definite  laws  based  upon 
the  principle  of  chemical  equivalence  among  the  elements.  In 
the  electrolysis  of  copper  sulphate  mentioned  above,  or  of  other 
metallic  salts,  a  given  current  liberates  the  metals  in  weights 
proportionate  to  their  chemical  equivalents. 

Hence  Faraday's  laws:  (i)  UAH  the  cells  in  a  circuit  have  in 
them  equivalent  amounts  oj  chemical  action"  (2)  " In  a  given 
time  the  chemical  action  in  a  cell  is  directly  proportionate  to  the 
current-strength" 

The  same  current  acting  separately  on  a  chlorid,  a  bromid, 
and  an  iodid  liberates  35  gm.  of  chlorin,  80  gm.  of  bromin,  and 
127  gm.  of  iodin.  These  figures  are  recognized  in  other  relations 
as  the  equivalents  (p.  63)  of  these  elements. 

The  gram  weights  of  an  element  set  free  in  one  second  by  a 
current-strength  of  one  ampere  is  called  the  electrochemical  equiv- 
alent. That  of  hydrogen  being  0.00001038,  from  law  (i)  we 
deduce  that  to  calculate  the  electrochemical  equivalent  of  any 
other  element,  it  is  only  necessary  to  multiply  0.00001038  by  the 
chemical  equivalent  of  that  element.  The  chemical  equivalent 
of  an  element  is  obtained  by  dividing  the  valency  into  the  atomic 
weight  (p.  114). 

Example:  The  chemical  equivalent  of  copper  being  63.2,  how 
many  grams  will  be  deposited  by  i  ampere  in  i  second?  Answer: 
63.2X0.00001038  =  0.00656  gm. 

From  law  (2)  we  deduce  that  the  mass  of  copper  liberated  is 
equal  to  the  product  obtained  by  multiplying  the  current-strength 
by  the  number  of  seconds,  and  then  by  the  chemical  equivalent. 

The  Ion  Theory. — The  best  explanation  of  the  facts  of  elec- 
trolysis is  afforded  by  the  theory  of  electrolytic  dissociation.  It 
assumes  that  aqueous  solutions  of  salts,  strong  acids,  and  bases 
contain  some  entire  molecules  of  the  compounds  and  some  that 
are  separated  into  ions,  having  charges  of  electricity.  The  ions 
with  their  opposite  +  and  —  electricities  are  attracted  to  the  oppo- 
site—and  +  poles,  and  thus  the  molecule  is  split  into  its  constituents, 
other  entire  molecules  become  ionized  to  take  their  place,  and 
these  in  turn  are  decomposed.  The  ion  theory  has  many 
phenomena  of  heat  and  chemical  action  to  support  it  (see  pp. 
128-132). 

THE  INDUCTION  COIL 

When  the  galvanic  current  passes  through  a  wire  (primary), 
it  induces  another  current  in  a  wire  (secondary)  near  to  it.  If 
the  coarse  primary  wire  be  insulated  and  coiled  about  a  core  of  iron, 
A,  Fig.  16,  and  a  much  longer  and  finer  wire  is  wound  outside, 
the  ends  of  this  secondary  wire  give  remarkable  displays  of  electro- 


CATHODE  AND  RONTGEN  RAYS 


S3 


motive  force  far  in  excess  of  those  obtainable  from  batteries  or 
electric  lighting  circuits.  Nothing  is  seen  so  long  as  the  primary 
current  is  flowing,  but  when  it  is  broken  a  vivid  spark  passes,  owing 
to  the  current  induced  in  the  secondary  coil  by  the  interruption  of 
that  in  the  primary.  To  secure  a  stream  of  sparks  a  rapid  opening 


FIG.  16. — Induction  coil.  A,  Core  of  iron  rods;  B,  condenser,  to  get  rid  of  the  extra  current  which 
runs  back  on  the  induced  current;  C,  spring  of  interrupter;  b,  iron  armature;  d,  set  screw  carrying 
platinum  point ;  z  c,  battery,  —  and  +  are  the  secondary  poles. 

and  closing  is  produced  in  the  primary  current  by  an  automatic 
interrupter  C  which  is  actuated  by  the  electromagnetism  of  the 
central  iron  core.  The  sparks,  coming  close  together,  give  intense 
effects,  apparently  continuous,  which  are  called  the  faradic, 
induced,  or  secondary  current. 


CATHODE  AND  RONTGEN  RAYS 

Under  ordinary  conditions  an  insulated  body  charged  by 
electricity  retains  its  charge  owing  to  the  fact  that  the  air  at  normal 
pressure  offers  high  resistance  to  leakage.  The  electricity  of  high 
potential  produced  by  an  influenced  electrical  machine  or  an 
induction  coil  overcomes  this  resistance  and  a  sudden  spark 
discharges  the  electrified  body.  By  lowering  the  air  pressure 
with  a  pump  the  spark  changes  in  appearance  to  a  luminous 
cloud  with  brilliant  bands. 

If  the  metallic  electrodes  are  fused  into  a  glass  bulb  which  is 
exhausted  of  air  (Crookes'  tube)  and  a  powerful  induced  current 
passes,  giving  a  spark  of  6  inches,  the  negative  electrode  (cathode) 
is  seen  as  a  disc  surrounded  by  a  pale  glow  beyond  which  is  a  dark 


54 


MAGNETISM    AND    ELECTRICITY 


space  which  extends  to  the  other  side  of  the  bulb.  The  glass 
directly  opposite  the  cathode  disc  glows  brilliantly  with  a  phos- 
phorescent light,  which  ordinarily  is  green  from  the  soda  in  the 
glass.  Negative  electricity  streams  from  the  cathode  disc  in 
straight  lines  until  it  impinges  upon  the  glass  wall  or  the  disc  of 
the  anode  as  a  target.  These  "cathode  rays"  are  considered  to 
be  a  flight  of  negatively  electrified  corpuscles  (electrons),  which 
are  the  same  no  matter  what  the  material  of  the  disc  from  which 
they  are  driven.  They  move  with  a  speed  nearly  equal  to  that 
of  light,  and  have  a  mass  a  thousand  times  less  than  that  of  a 
hydrogen  atom.  While  they  do  not  penetrate  the  glass  wall  of 
the  bulb,  they  can  pass  through  a  window  in  it  made  of  aluminium 
foil,  which  is  of  lower  density,  and  when  outside  are  known  as 
Lenard  rays. 

Beside  these  rays  the  glass  of  the  bulb  transmits  a  very  different 
set  of  invisible  rays  which  are  produced  by  the  impact  of  the 


FIG.  17. — Thomson's  vacuum  regulator  tube. 

electrons  upon  the  glass  wall  or  the  target  of  the  anode.  They 
not  only  pass  through  the  glass  and  light  up  the  dark  screen  of 
a  fluoroscope  covered  with  barium  or  calcium  tungstate,  affect 
photograph  plates,  and  act  physiologically  on  animal  tissues  and 
organs,  but  do  these  things  after  penetrating  enclosures  made  of 
opaque  substances.  They  are  called  "#-rays,"  because  their  nature 
was  at  first  unknown,  and  Rontgen  rays}  after  their  discoverer. 
They  are  supposed  to  be  due  to  irregular  pulsations  in  the  ether, 
(not  a  train  of  waves)  caused  by  the  bombardment  of  the  target 
with  the  electrons.  The  rays  are  absorbed  by  different  materials 
of  a  given  thickness,  roughly  in  proportion  to  their  density.  As 
dense  bodies  like  bone  or  metal  absorb  more  than  flesh  and  leather, 
the  rays  penetrating  a  part  of  the  animal  body  or  a  leather  purse 
and  afterward  striking  a  photograph  plate  or  a  fluoroscope,  make 
a  shadow  picture  (skiagraph)  of  the  bones  in  the  flesh  or  the 
coins  in  a  purse. 

Cathode  rays  are  also  emitted  from  certain  substances  without 
the  electric  discharge,  but  after  exposure  to  light  especially  to  the 
ultra-violet.  The  radio-active  metals,  uranium,  thorium,  actinium, 


SPECTROSCOPY  55 

polonium,  and  radium  give  off  both  cathode  and  Rbntgen  rays 
incessantly,  without  the  stimulus  of  light  or  electricity  (p.  247). 

Another  important  property  of  the  Rontgen  ray  is  that  of 
converting  non-conducting  air  or  other  gases  into  conductors  of 
electricity.  The  charge  of  an  electroscope  disappears  when  it  is 
brought  near  any  radio-active  body,  the  rapidity  of  this  silent 
discharge  being  proportional  to  the  radio-activity.  The  air  is 
supposed  to  be  ionized  by  the  contact  of  the  radiating  electrons, 
and  the  ions  carry  off  the  electricity. 


LIGHT 

SPECTROSCOPY 

When  a  round  beam  of  white  light,  S  (Fig.  18),  passes  through 
a  prism,  P,  it  does  not  pursue  a  straight  course,  as  a  pencil  of  light, 
to  form  a  white  circle  at  K,  but  is  bent  or  refracted  at  an  angle 
toward  the  base  of  the  prism.  On  emerging  from  the  prism  it 
is  found  to  be  decomposed  into  different  colored  lights  which 
diverge  to  form,  on  the  screen  H,  a  brilliant  band  called  the 
spectrum.  This  dispersion  of  the  component  colors  is  due  to  the 


FIG.  18. — Dispersion  by  a  prism. 

fact  that  the  several  colored  lights  have  unequal  wave-lengths. 
The  dense  medium  of  the  prism  retards  the  short  waves  more 
than  the  long  ones,  and  hence  the  short  waves  of  violet  at  one 
end  are  refracted  more  than  the  longer  ones  of  red  at  the  other 
end.  In  the  continuous  spectrum  from  the  light  of  candles,  lamps, 
or  incandescent  solids,  six  principal  groups  of  colors  are  desig- 
nated: violet,  blue,  green,  yellow,  orange,  and  red.  If  the  artificial 
light  have  color  in  it,  the  spectrum  will  show  that  color  predomi- 
nating and  the  others  less  bright.  (PI.  4,  Fig.  i,  a.) 

When  the  spectrum  is  obtained  from  sunlight  passing  through 


56  LIGHT 

a  slit,  it  appears  as  a  band  of  bright  colors  crossed  by  a  number 
of  fine  black  lines,  called  Fraunhofer's  lines  (Fig.  19).  These  are 
always  present  in  the  same  relative  position.  They  are  con- 
sidered as  shadows  caused  by  the  absorption  of  certain  rays  in 
their  passage  through  media.  Dark  lines  or  bands  crossing  the 
otherwise  continuous  spectra  are  obtained  by  transmission  of  the 
pencil  of  light  through  colored  solids,  liquids,  or  gases.  Such 
spectra  are  called  absorption  spectra.  In  PI.  4,  Fig.  i,  b,  c,  d,  are 
shown  the  dark-banded  spectra  of  blood. 

Red.      Orange.     Yellow.        Green.  Blue.  Indigo.    Violet. 

-"^-i^^% 

H 


Na. 


Tl. 


FIG.  19.— Fraunhofer's  lines:    i.  Solar  spectrum  (the  colors  are  indicated  above);  2-7,  bright-line 
spectra  of  incandescent  gases. 

The  light  emitted  by  a  glowing  gas  forms  a  spectrum  of  dis- 
connected bright  lines  and  not  of  continuous  colors,  as  indicated 
in  the  table  of  spectra  of  different  metals  when  heated  to  form 
incandescent  vapors.  In  Fig.  19  the  position  of  different  lines 
can  be  determined  by  reference  to  the  scale  at  the  top,  and  also 
by  the  Fraunhofer's  lines.  As  the  spectra  of  different  substances 
always  give  different  combinations  of  lines  and  bands,  an  impor- 
tant means  of  identification  is  afforded  by  spectrum  analysis. 

The  spectroscope  is  an  instrument  for  studying  the  spectra. 
It  consists  of  a  slit  at  v  (Fig.  20),  for  which  there  is  an  adjustable 
shutter  to  regulate  the  beam  of  light  emitted  by  the  incandescent 


SPECTROSCOPY  57 

metal  or  that  transmitted  through  blood  or  other  colored  media. 
In  the  telescope  B  there  is  a  lens  for  collecting  the  light  of  the  slit 
in  parallel  rays  and  throwing  it  upon  the  prism  P.  The  telescope 
A  serves  for  the  observer  to  catch  the  dispersed  light  after  emerg- 
ing from  the  prism,  and  telescope  C  gives  the  image  a  standard 
scale  in  millimeters,  illuminated  by  the  candle  F  and  reflected  by 
the  face  of  the  prism,  so  that  the  observer  sees  it  in  front  of  the 
spectrum.  By  this  micrometer  scale  the  relative  distances  of  the 
bands  and  lines  can  be  noted. 

The  direct-vision  spectroscope  is  a  single  brass  tube  having  an 
adjustable  slit,  a  lens  focussing  the  parallel  rays  upon  a  series  of 
prisms,  two  of  flint  and  three  of  crown  glass,  arranged  in  a  direct 
line  between  the  light  and  the  eye.  The  combination  of  different 
prisms  decomposes  the  light  without  deflecting  it  from  the  straight 
path. 


FIG.  20. — Spectroscope. 

The  spectra  in  Fig.  19  were  exhibited  by  salts  of  the  metals 
indicated  in  symbols  when  heated  on  the  tip  of  a  platinum  needle 
in  a  Bunsen  flame.  The  spectrum  at  the  top  shows  some  of  the 
most  important  of  the  Fraunhofer  dark  lines,  marked  with  the 
letters  by  which  they  are  usually  designated.  The  spectrum  of 
sodium  (Na)  has  a  brilliant  yellow  line  (D) ;  potassium  (K)  has 
two  characteristic  lines,  one  red  (A),  the  other  violet;  lithium 
(Li) ,  a  brilliant  red  and  a  fainter  orange  line.  The  important  lines 
of  strontium  (Sr)  are  in  the  yellow,  red,  and  blue;  barium  (Ba), 
in  the  green;  rubidium  (Rb),  in  the  violet  and  dark  red;  cesium 
(Cs),  in  the  blue;  and  thallium  (Tl),  in  the  green. 

Beyond  the  visible  limits  of  the  solar  spectrum  at  both  ends 
there  are  invisible  rays  recognized  by  their  heating  (calorific)  and 


58  LIGHT 

their  chemical  (actinic)  effects.  Not  more  than  one-fourth  of  the 
rays  of  the  solar  spectrum  are  visible.  At  one  end  the  calorific 
rays  have  longer  wave-lengths  than  the  visible  red,  and  hence  are 
called  infrared  rays.  At  the  other  end  actinic  rays  are  more  re- 
frangible and  have  shorter  wave-lengths  than  the  luminous  violet, 
and  hence  are  called  ultraviolet  rays.  When  a  solution  of  quinin 
sulphate  is  placed  in  this  dark  ultraviolet  region,  pale-blue  rays 
are  seen.  Substances  which,  like  quinin  and  kerosene,  have  the 
property  of  being  colorless  by  transmitted  light  and  of  lighting 
up  when  observed  in  reflected  light,  are  said  to  be  fluorescent. 
They  lessen  the  speed  of  the  invisible  ultraviolet  rays  and  thus 
lower  their  refrangibility,  bringing  them  within  the  limits  percept- 
ible to  the  eye  and  reflecting  them. 

The  Ethereal  Waves. — The  universe  is  supposed  to  be  per- 
vaded by  an  elastic  medium  known  as  the  ether,  which  can  vibrate 
from  side  to  side.  The  rate  of  vibrations,  according  as  they 
are  fast  or  slow,  causes  a  variety  of  effects.  While  all  of  them 
travel  by  impulses  from  their  sources  at  the  same  speed  as  light 
(300,000  kilometers  or  186,000  miles  a  second),  their  oscillations 
from  side  to  side  may  be  slower  than  2  or  3  to  the  minute  and 
faster  than  one  million  times  a  minute.  The  very  slow  waves 
are  the  electric  Hertzian  waves  used  in  wireless  telegraphy; 
much  faster  are  the  waves  of  radiant  dull  heat;  still  faster,  red 
light;  then  yellow,  and  on  through  the  colors  of  the  spectrum  to 
violet;  at  a  higher  rate  are  the  ultraviolet  rays.  The  #-rays  of 
Rontgen  issuing  from  a  Crookes'  tube  are  probably  a  series  of  short 
pulses  in  the  ether  sent  out  at  irregular  intervals.  Being  irregular 
and  unlike  a  train  of  waves,  they  are  not  lost  in  the  regular  vibra- 
tions of  surrounding  bodies,  but  are  transmitted  with  little  change. 


POLARIMETRY 

Iceland  spar  and  some  other  crystals  possess  the  peculiar 
property  of  splitting  a  transmitted  ray  of  light  into  two  parts. 
An  object  viewed  through  such  crystals  shows  two  images,  one 
being  .made  by  the  ordinary  rays  of  light  corresponding  to  single 
refraction,  and  the  other  by  the  extra-ordinary,  which  differs  from 
the  commonly  refracted  light.  If  these  extraordinary  rays  are 
sent  through  a  second  similar  crystal,  and  the  second  crystal  be 
rotated,  two  of  the  rays  disappear  and  the  field  of  view  becomes 
dark;  further  rotation  causes  return  of  brightness. 

The  effect  of  the  first  crystal  has  been  to  alter  the  light  so 
that  the  second  crystal,  at  right  angles,  does  not  transmit  the 
modified  ray.  The  light  is  said  to  be  polarized — that  is,  made  to 
vibrate  in  one  plane.  Light  commonly  vibrates  in  all  planes, 


POLARIMETRY  59 

though  for  convenience  it  may  be  regarded  as  in  two  planes  at 
right  angles.  The  eye  detects  no  difference  between  common 
and  polarized  light,  hence  to  determine  the  presence  of  this  prop- 
erty a  second  crystal  must  be  used,  called  the  analyzer.  In  Fig. 
21  the  set  of  vertical  rods  (A)  represents  the  first  crystal  or  polar- 
izer, stopping  the  rays  in  a  horizontal  plane,  but  allowing  the 
vertical  to  pass.  B  is  the  analyzer,  placed  at  right  angles,  and 
causing  darkness  by  stopping  the  rays  vibrating  in  the  vertical 
plane.  If  B  be  rotated  sufficiently,  the  polarized  ray  passes 
readily  and  the  light  reappears. 

Having  set  the  polarizer  and  analyzer  ai  the  angle  to  stop 
both  planes,  it  is  possible  to  turn  the  ray  of  light  to  the  trans- 
mitting plane  by  putting  between  them  certain  substances  which 
rotate  the  rays  to  the  right  or  left.  Among  the  substances  having 
this  rotating  property  are  quartz,  the  sugars,  proteins,  and  biliary 
acids;  they  are  classed  as  optically  active.  Those  substances  that 
cause  opacity  or  a  shadow  when  the  analyzer  is  rotated  to  the 
right  (expressed  by  the  sign  +  )  are  said  to  be  dextrogyrous  (such 


FIG.  21. — Action  of  polarizer  and  analyzer. 

as  dextrose),  while  those  so  acting  by  the  opposite  movement 
(expressed  by  the  sign  —  )  are  called  levogyrous  (as  levulose). 
Having  determined  the  direction  and  the  number  of  degrees  of 
rotation  of  the  plane  of  polarized  light  caused  by  a  solution,  its 
composition  and  concentration  may  be  ascertained.  The  degree 
of  rotation  corresponds  to  the  amount  of  the  optically  active  sub- 
stance in  solution;  that  is  to  say,  the  twist  given  to  the  ray  depends 
on  the  number  of  molecules  which  it  passes  on  its  way.  In  the 
polariscope  the  polarizing  and  analyzing  crystals  used  are  specially 
cut  rhombs  of  Iceland  spar,  called  Nicol's  prisms.  These  deflect 
the  ordinary  ray  from  the  straight  path  and  extinguish  it,  but 
permit  the  extraordinary  ray  to  pass  through. 

Laurent's  half=shadow  polarimeter  is  the  instrument  seen 
in  section  in  Fig.  22.  At  A  is  a  yellow  flame,  which  is  best  ob- 
tained by  heating  a  sodium  salt  in  a  Bunsen  burner;  but  a  gas 
flame  may  be  used  and  the  monochromatic  yellow  color  imparted 
as  the  light  passes  through  the  plate  of  potassium  bichromate  at 
B.  It  then  passes  through  the  Nicol's  prism  (P),  the  rays  in  the 
horizontal  plane  emerging  as  polarized  light;  those  in  the  per- 


6o 


LIGHT 


pendicular  plane  are  deflected  and  stopped  by  a  diaphragm.  At 
D  the  light  is  modified  by  a  diaphragm,  one-half  of  which  is 
covered  by  a  thin  plate  of  quartz,  cut  so  as  to  have  but  little 
rotating  power.  The  circle  below  D  shows  the  diaphragm  divided 
in  perpendicular  halves  by  the  quartz  plate.  A  tube  of  brass, 
i  decimeter  long,  closed  at  both  ends  with  disks  of  glass,  is  filled 
with  the  solution  to  be  tested  and  inserted  at  T  in  the  path  of  the 
polarized  ray. 

The  eyepiece  (O)  contains  a  lens  and  the  analyzing  prism  (N), 
the  whole  tube  rotating  on  its  long  axis  as  the  vernier  arm  is 
moved  around  a  cirgle  graduated  in  degrees.  When  the  tube  (T) 


FIG.  22. — Laurent's  half -shadow  polarimeter. 

contains  water  and  the  vernier  is  at  o°,  the  eyepiece  being  focused 
on  the  vertical  line  of  the  diaphragm,  the  two  sides  should  be 
equally  illuminated,  as  in  the  circle  i.  If  one  side  be  darker,  then 
the  polarizer  must  be  rotated  by  the  screw  at  P  until  both  sides 
are  alike.  When  a  solution  of  sugar  or  albumin,  or  other  optically 
active  substance,  is  introduced  into  the  tube  only  one  side  of  the 
diaphragm  is  unshaded,  as  in  circles  2  albumin  and  3  sugar.  By 
moving  the  vernier  around  the  circle,  to  the  left  for  2  and  to  the 
right  for  3,  both  sides  of  the  diaphragm  become  equally  illu- 
minated, as  in  circle  4,  and  the  reading  of  the  instrument  gives 
at  once  the  angle  of  rotation  of  the  solution  in  the  tube  ( T). 

The  expression  specific  rotating  power  or  specific  rotation  of  a 


POLARIMETRY  6 1 

substance  means  the  extent  of  rotation  (expressed  in  degrees) 
caused  by  i  gm.  of  that  substance  dissolved  in  i  c.c.  of  liquid, 
examined  in  a  tube  i  decimeter  long. 

If  a  be  the  observed  angle,  p  the  number  of  grams  of  substance 
in  i  c.c.,  /  the  length  of  the  tube  in  decimeters,  and  the  specific 
rotation  for  the  yellow  light  (D)  of  the  spectrum  be  designated  by 

(a)D,  then  the  formula  would  be  (a)D=  d=-j.  The  specific  rota- 
tion of  glucose  is  stated  as  (a)^= +52.5°;  that  is,  a  rotation  of 
the  ray  to  the  right  52.5°  is  caused  by  100  gm.  of  the  substance 
in  100  c.c.  of  water.  Therefore,  with  a  one-decimeter  tube  i°  = 

—^—  gm.  in  100  c.c.     Example:  A  specimen  of  diabetic  urine  at 

o°  showed  the  disc  half-shaded,  as  at  3,  Fig.  22,  and  using  a 
one-decimeter  tube  (T,  Fig.  22)  required  2°  of  dextrorotation 

,  .„                           .       .    ,         „.                      100X2      200 
to  get  equal  illumination,  as  in  circle  4,  Fig.  22,  then  — -  =  — 

=  3.8  per  cent,  glucose. 

The  polarimetry  of  urine  requires  that  the  specimen  should 
first  be  made  free  of  albumin,  which  rotates  as  far  to  the  left 
(circle  2,  Fig.  22)  as  glucose  does  to  the  right  (circle  3,  Fig.  22), 
its  formula  being  (a)D=  —  56°.  If  albumin  be  detected,  then 
the  urine  must  be  acidulated,  boiled,  and  filtered  before  testing 
with  the  polarimeter. 

In  most  cases  of  diabetic  urine  the  concentration  of  sugar  is 
small,  and  the  longer  tube  (2  decimeters)  is  used  to  contain  it. 
With  this  tube  the  reading  is  divided  by  2  before  the  percentage 
calculation  is  made;  some  medical  polariscopes  are  graduated 
to  read  percentage  of  glucose  direct. 

An  accurate  adjustment  of  the  reading  may  require  that  the 
urine  be  decolorized.  This  is  done  simply  by  adding  i  drop  of 
acetic  acid  and  shaking  with  a  test-tube  full  of  urine  a  small  piece 
of  lead  acetate  and  filtering  off  the  precipitate.  Another  method 
is  to  put  J  c.c.  of  washed  blood-charcoal  in  a  test-tube  full  of 
urine,  then  shake  and  filter.  It  must  be  remembered  that  a 
trace  of  maltose  may  be  present,  though  rarely,  and  may  increase 
the  angle,  as  it  rotates  more  than  glucose — (a)^=  + 140°.  It 
does  not  ferment  so  readily  as  glucose.  Diabetic  urine  some- 
times contains  /5-oxybutyric  acid,  which  rotates  to  the  left — (#)/>  = 
—  24.2° — and  hence  may  reduce  the  glucose  reading  or  neutralize 
it  altogether.  The  difference  between  the  dextrorotation  before 
fermentation  and  that  afterward  would  show  the  presence  and 
amount  of  the  glucose  alone.  At  room  temperature  20°  C. 
(68°  F.)  the  specific  rotation  of  cane-sugar  is  (d)D=  +66.5°; 
malt  sugar  +137.0°;  levulose  — 93.0°,  and  invert  sugar  — 20.2 


o 


62  THE    CHEMICAL    ELEMENTS 


THE  CHEMICAL 

CHEMISTRY  is  that  branch  of  science  that  deals  with  the  prop- 
erties and  composition  of  substances,  and  studies  the  phenomena 
attending  changes  of  composition. 

When  water  by  variations  of  temperature  becomes  ice  or 
steam,  it  has  undergone  a  physical  change,  due  to  the  play  be- 
tween two  physical  energies:  cohesion  and  heat.  When  glass 
or  sealing-wax  is  rubbed  it  acquires  the  property  of  attracting 
feathers,  pith-balls,  and  paper,  by  virtue  of  a  transient  physical 
power,  the  electric  energy.  When  iron  is  made  red-hot  or  when  it 
is  magnetized,  it  remains  iron  still,  but  when  it  rusts  it  loses  its 
magnetic  qualities  and  is  transformed  into  a  substance  of  wholly 
different  properties.  The  energy  which  rusts  iron,  which  burns 
coal,  which  turns  milk  sour,  which  changes  wine  into  vinegar  is 
not  physical,  but  chemical. 

The  chemical  energy  or  affinity  acts  between  different  kinds  of 
matter,  causing  them  to  lose  their  characteristic  properties  in 
forming  a  new  substance.  While  its  operations  are  correlated 
with  those  of  physical  energy,  it  is  peculiar  in  that  it  produces 
permanent  change  in  bodies.  The  change  is  more  profound  than 
that  induced  by  mechanical  mixture. 

If  powdered  iron  and  powdered  sulphur  are  mixed  by  tritura- 
tion  in  a  mortar,  to  the  naked  eye  a  change  in  color  is  visible,  the 
yellow  and  black  making  brown;  but  under  the  microscope  we 
can  distinguish  the  iron  particles  as  separate  from  those  of  sul- 
phur. The  particles  of  iron  are  still  magnetic  and  can  be  removed 
by  the  touch  of  a  magnet.  The  sulphur  can  be  dissolved  out  by 
treating  the  mixture  with  carbon  bisulphid.  Wlien,  however,  the 
original  mixture  is  ignited,  the  iron  and  the  sulphur  unite  by 
chemical  affinity,  and  now  the  microscope  fails  to  detect  the 
two  different  substances;  the  magnet  will  not  separate  the  iron, 
nor  the  carbon  bisulphid  dissolve  the  sulphur.  Chemical  energy 
is  distinguished  further  by  the  fact  that  its  action  is  limited  to 
definite  weights  of  matter,  while  a  mechanical  mixture  can  be 
made  of  ingredients  in  any  proportion. 

All  natural  objects,  suns,  planets,  the  mineral  strata  of  the 
earth,  its  bodies  of  water,  and  its  aerial  envelop,  the  living  things 
that  crowd  its  surface,  the  molecules  and  atoms,  are  held  in  place 
by  an  energy  which  manifests  itself  in  the  phenomena  of  gravita- 
tion, of  cohesion,  and  of  chemical  affinity.  Gravitation  affects 
all  forms  of  matter  at  all  distances;  cohesion  acts  on  molecules  at 
distances  immeasurably  small;  chemical  affinity  acts  upon  the 
minute  atoms  at  insensible  distances,  causing  such  transformations 


THE    CHEMICAL    ELEMENTS  63 

of  the  bodies  acted  upon  that  they  can  no  longer  be  recognized 
by  ordinary  means. 

Elements  and  Compounds.— All  forms  of  matter  may  be 
divided  into  two  classes,  compounds  and  elements.  Most  natural 
objects  are  compound — that  is,  bodies  that  can  be  decomposed 
into  simpler  kinds  of  matter.  They  consist  of  two  or  more  ele- 
ments united  by  chemical  affinity.  Elements  are  the  simplest 
constituents  of  a  compound  into  which  it  is  decomposed.  While 
some  of  them  occur  free  in  nature,  most  of  them  are  obtained  by 
chemical  separation  of  the  part?  of  a  compound.  The  resolution 
of  a  compound  into  its  parts  is  called  analysis,  while  the  building 
up  of  a  compound  by  combining  its  parts  is  called  synthesis. 
Every  element  has  a  constant  combining  equivalent  (p.  114)  and 
has  never  been  known  to  enter  any  compound  in  less  proportion 
than  this  equivalence.  It  is  also  characterized  by  a  definite  spec- 
trum (p.  55)  as  a  distinct  species  of  matter. 

The  diversity  of  matter  in  the  more  than  300,000  forms  seen 
in  the  universe  is  due  to  variations  in  the  kind  and  the  proportion 
of  the  elements  engaged.  Science  has  as  yet  found  100  odd  simple 
bodies  or  elements.1  Of  the  elements  now  identified  not  more 
than  40  are  of  any  practical  medical  importance;  the  others  are 
rarely  encountered.  Those  deserving  attention  will  be  found 
in  the  following  tables,  each  accompanied  by  its  symbol,  which 
is  either  the  initial  letter  of  the  English  or  Latin  name,  or  that 
letter  combined  with  a  significant  small  letter  taken  from  the  name. 
The  combining  equivalents  in  round  numbers  are  given  in  the 
third  column. 

The  elements  are  broadly  divided  into  two  classes:  non-metals 
and  metals,  each  having  properties  generally  characteristic.  Non- 
metals  physically  have  low  specific  gravity  and  are  poor  con- 
ductors of  heat  and  electricity;  chemically  they  form  acids.  Metals 
have  high  specific  gravity  and  metallic  luster,  are  good  conductors, 
of  heat  and  electricity,  and  form  bases. 

Some  Non-metals 

Name.  Symbol. 

Oxygen  O  16 

Hydrogen  H  I 

Nitrogen  N  14 

Carbon  C  12 

Boron  B  1 1 

Silicon  Si  28 


Name.  Symbol. 

Fluorin  F  19 

Chlorin  Cl  35-5 

Bromin  Br  80 

lodin  I  127 

Sulphur  S  32 

Phosphorus  P  31 


1  There  is  no  escape  from  the  conclusion  that  the  cathode  electric  rays  of  a 
Crookes  tube  are  disembodied  charges  of  negative  electricity  or  electrons,  in  which 
the  subdivision  is  carried  much  further  than  in  the  ordinary  molecule  or  even 
atom.  The  atoms  of  different  chemical  elements  seem  to  be  different  aggregations 
of  the  same  primordial  electrons.  The  phenomena  of  radio-activity  exhibited  by 
the  element  radium  are  explained  on  p.  247  by  this  hypothesis. 


64 


THE    CHEMICAL    ELEMENTS 


All   of  the   above,   except   hydrogen   and   oxygen,   form   acids 
when  united  with  those  two  elements. 

Some  Metals 


Name. 

Symbol. 

Combining 
equivalents. 

Name. 

Symbol. 

Combining 
equivalents. 

Potassium 

K    (Kalium) 

39 

Zinc 

Zn 

65 

Sodium 

Na  (Natrium) 

23 

Nickel 

Ni 

5* 

Lithium 

Li 

7 

Cobalt 

Co 

59 

Barium 

Ba 

137 

Iron 

Fe 

(  Ferrum) 

56 

Strontium 

Sr 

87.5 

Manganese 

Mn 

55 

Calcium 

Ca 

40 

Chromium 

Cr 

52 

Magnesium 

Mg 

24 

Tin 

Sn 

(Stannum) 

118 

Aluminium 

Al 

27 

Copper 

Cu 

(Cuprum) 

63 

Arsenic 

As 

75 

Lead 

Pb 

(  Plumbum) 

207 

Antimony 

Sb  (Stibium) 

1  20 

Mercury 

Hg 

(  Hydrargyrum)   200 

Bismuth 

Bi 

208 

Gold 

Au 

(Aurum) 

197 

Cadmium 

Cd 

112 

Platinum 

Pt 

195 

Some  of  the  above-named  metals,  such  as  arsenic  and  antimony, 
might  with,  equal  reason  be  classified  along  with  the  non-metals 
nitrogen  and  phosphorus,  which  they  closely  resemble  in  their 
chemical  traits.  Most  of  the  true  metals  will  form  bases  by  union 
of  their  oxids  with  water. 

Chemical  compounds  are  usually  considered  in  two  great 
classes,  the  Inorganic  and  the  Organic,  though  the  line  of  demar- 
cation is  one  made  for  convenience  and  is  not  drawn  by  nature. 
Inorganic  compounds  are  of  mineral  origin,  not  requiring  a  living 
organism  to  produce  them.  Examples  are  water,  lime,  and  com- 
mon salt.  Organic  compounds  are  those  which,  as  found  in  nature, 
are  produced  exclusively  by  the  action  of  organized  animal  or 
vegetable  life.  Examples  are  fat,  albumin,  starch,  and  sugar. 
As  carbon  is  invariably  present  in  organic  substances,  organic 
compounds  are  sometimes  called  carbon  compounds.  Beside 
carbon,  they  usually  contain  oxygen  and  hydrogen,  and  very  often 
nitrogen.  Owing  to  the  marked  traits  of  these  four  non-metals, 
they  are  especially  fitted  for  study  as  types  illustrating  the  prin- 
ciples of  chemical  philosophy.  Hence  they  are  often  termed 
Typic  Elements.  They  are  of  the  greatest  importance  to  the 
physiologist  in  his  study  of  nutrition  and  animal  heat.  On  these 
accounts  in  the  following  pages  extended  treatment  is  given  to 
the  compounds  of  these  elements. 

The  body  of  a  living  animal  contains  about  60  per  cent,  water 
and  40  per  cent,  solids.  They  exist  as  more  or  less  complex  com- 
pounds of  elements,  which  are  abundant  in  the  following  order  of 
percentage:  Oxygen,  66.0;  carbon,  17.5;  hydrogen,  10.2;  nitrogen, 
2.4;  calcium,  1.6;  phosphorus,  0.9;  sodium,  0.3;  chlorin,  0.3;  sul- 
phur, 0.2;  magnesium,  0.05;  iron,  0.004;  an<3  traces  of  iodin. 
fluorin,  silicon,  copper,  manganese,  and  lithium. 


OXYGEN  65 

Notation. — The  symbols  H,  O,  etc.,  stand  not  only  for  the 
element,  but  for  a  chemical  unit  of  the  element.  When  more 
than  one  unit  is  expressed  a  large  numeral  is  written  before,  mul- 
tiplying all  the  symbols  that  follow  it,  as  2H,  or  a  small  numeral 
is  placed  to  the  right  and  below  the  symbol,  as  H2,  for  2  units  of 
hydrogen.  To  express  admixture  of  elements  the  plus  sign  is 
used,  thus  H2  +  O  means  that  2  units  of  hydrogen  are  mixed  with 
i  of  oxygen.  To  express  union  or  combination  the  symbols  are 
put  as  close  together  as  the  type  will  go;  thus  2H2O  means  two 
parts  of  the  compound  formed  when  hydrogen,  two  units,  and 
oxygen,  one  unit,  unite  by  chemical  attraction. 


NON-METALS 

Classification.— It  is  assumed  that  the  medical  student  is 
a  beginner  in  chemistry,  and  as  yet  is  unfitted  to  appreciate  the 
reasons  for  arranging  the  elements  according  to  the  natural  or 
scientific  classification  (see  page  116).  The  considerations  which 
make  the  most  logical  system  desirable  will  be  understood  only 
after  the  principles  of  chemical  philosophy  have  been  studied. 
These  principles  will  be  elucidated  in  the  course  of  studying  the 
Typic  Elements — oxygen,  hydrogen,  nitrogen,  and  carbon,  and 
their  compounds.  These  will  be  first  considered  in  the  order 
best  suited  for  the  intellectual  needs  of  the  student,  though  ref- 
erence will  be  made  to  the  more  systematic  grouping  given  below: 

GROUP      I.   Hydrogen,  unique  (Monovalent). 

GROUP  II.  Halogens  or  the  chlorin  family  :  chlorin,  bromin,  iodin,  and  fluorin 
(Monovalent). 

GROUP  III.  The  oxygen  family  :  oxygen,  sulphur,  selenium,  and  tellurium  (Di- 
valent). 

GROUP  IV.  The  nitrogen  family  :  nitrogen,  phosphorus,  arsenic,  and  antimony 
(Trivalent). 

GROUP    V.  The  argon  family :  argon,  helium,  neon,  crypton,  xenon. 

GROUP  VI.   The  carbon  family  :  carbon,  silicon,  (Quadrivalent). 

OXYGEN 

Symbol,  O.     Atomic  weight,  16. 

History. — The  discovery  of  oxygen  was  an  incident  in  the 
study  of  the  composition  of  the  atmosphere.  The  early  Greek 
philosophers  regarded  the  air  as  an  element,  as  they  did  the  earth, 
fire,  and  water. 

Its  complex  nature  was  suspected  when,  early  in  the  seventeenth 
century,  the  observation  was  made  that  by  combustion  in  a 


66  NON-METALS 

confined  portion  of  air,  the  air  lost  weight,  and  that  the  remainder 
would  support  neither  life  nor  fire.  Priestley  showed  that  by 
heating  mercury  in  enclosed  air  for  several  days  at  a  temperature 
near  its  boiling-point,  the  mercury  was  changed  to  a  red  powder, 
now  called  mercuric  oxid,  while  the  life-sustaining  part  of  the 
air  disappeared.  In  1774  he  found  that  by  heating  mercuric 
oxid  a  gas  was  liberated  which,  when  mixed  with  the  burnt-out 
air,  would  restore  to  it  the  properties  of  supporting  respiration 
and  combustion. 

This  operation  is  performed  in  a  hard  glass  reduction  tube 
or  retort,  and-  the  gas  collected  over  water  in  a  pneumatic  trough, 
the  mercury  being  condensed  on  the  cooler  part  of  the  glass  tube. 
The  result  may  be  written  as  follows: 

Mercuric  oxid  yields  mercury  and  oxygen. 

Or,  by  short  hand, 

HgO  Hg  +       O. 

Preparation. — Many  higher  oxids,  as  manganese  dioxid, 
MnO2;  lead  dioxid,  PbO2;  and  barium  dioxid  BaO2,  yield  a  part 
of  their  oxygen  when  heated.  Barium  dioxid  above  400°  C. 
(752°  F.)  gives  off  half  of  its  oxygen. 

BaO2  BaO          +          O. 

Barium  dioxid.  Barium  monoxid. 

This  lower  oxid,  BaO,  heated  at  a  lower  temperature  in  a  cur- 
rent of  air,  takes  up  the  oxygen  it  had  lost.  By  alternating  these 
processes  oxygen  is  now  manufactured  on  a  commercial  scale  at 
a  low  cost. 

The  alkaline  peroxides  are  convenient  sources.  Fused  sodium 
dioxid  with  a  fractional  per  cent,  of  a  catalytic  agent  is  sold  for  this 
purpose  as  "Oxone."  Put  in  water  it  yields  half  of  its  oxygen. 

Na2O2       =       Na2O       +       O. 

In  the  laboratory  potassium  chlorate  is  the  source.  When 
this  compound  is  heated,  it  parts  with  its  oxygen,  leaving  potassium 
chlorid  in  the  retort. 

KC1O3  KC1        +        30. 

Potassium  chlorate.  Potassium  chlorid. 

It  is  customary  to  employ  a  mixture  of  coarsely  powdered 
manganese  dioxid  i  part  and  potassium  chlorate  2  parts.  This 


OXYGEN  67 

causes  the  KC1O3  to  yield  oxygen  at  a  comparatively  low  tem- 
perature, 200°  C.  (372°  F.).  The  manganese  dioxid  is  not  de- 
composed, though  its  presence  causes  the  easy  transmission  of 
oxygen  from  the  chlorate. 

Precaution. — The  materials  should  be  dry  and  free  from 
organic  dirt.  Serious  explosions  have  happened  from  the  action 
of  oxygen  on  the  carbon  of  coal-dust  or  other  impurities  in  com- 
mercial manganese  dioxid.  To  guard  against  such  accidents 


FIG.  23. — Collection  of  gas  disengaged  by  heat. 

a  small  sample  should  be  tested  by  heating  with  some  potassium 
chlorate  in  an  open  test-tube. 

In  preparing  oxygen  for  inhalation  it  is  advisable  to  free  it 
from  all  traces  of  chlorin  by  passing  the  gas  through  potassium 
hydroxid  in  a  wash  bottle  before  collecting  it  in  the  gas  bags  or 
gasometer.  Before  removing  the  lamp  withdraw  the  delivery 
tube  from  the  water,  if  collected  in  a  pneumatic  trough,  or  the 
regurgitation  of  the  water  will  cause  an  explosion.  In  making 
a  quantity  of  the  gas  it  is  customary  to  use  a  copper  retort  for  the 
potassium  chlorate.  In  practice  250  gm.  (8  oz.,  Troy)  of  the 
chlorate  yields  about  68  L.  (18  gal.)  of  oxygen  gas. 

Occurrence. — Oxygen  is  the  most  abundant  element.  It  is 
found  widely  distributed  in  nature,  forming  one-fifth  part  of  the 
volume  of  the  air  and  eight-ninths,  by  weight,  of  all  water.  As  an 
ingredient  in  most  minerals  it  makes  up  nearly  one-half  of  the 


68  NON-METALS 

weight  of  the  earth's  crust,  and  it  is  present  in  almost  all  animal 
and  vegetable  compounds. 

Physical  Properties. — Oxygen  is  a  little  heavier  than  air, 
its  specific  gravity  being  1.10563  (air=i).  It  is  an  invisible  gas, 
colorless,  tasteless,  and  odorless.  It  is  slightly  soluble  in  water, 
0.04  volume  dissolving  in  i  volume  of  water  at  o°  C.  (32°  F.). 
In  the  proportion  of  about  3  per  cent,  by  volume  it  is  dissolved  in 
natural  water  at  ordinary  temperatures,  and  furnishes  to  the  gills 
of  fishes  the  amount  needed  for  the  aeration  of  their  blood.  It 
has  been  liquefied  at  — 118°  C.(  —  244.4°  F«)  under  a  pressure  of 
50  atmospheres.  These  are  called  its  critical  values. 

Chemical  Properties. — It  has  affinities  of  great  power  and 
-wide  range,  combining  with  every  element  except  fluorin  and  the 
argon  group.  As  the  air  is  practically  one-fifth  part  oxygen 
diluted,  all  its  chemical  reactions  are  those  of  this  gas.  There 
is  this  difference  only:  the  pure  oxygen  causes  far  more  intense 
displays  of  energy.  By  attaching  various  combustibles  to  copper 
wire,  first  igniting  them  in  the  air  and  afterward  plunging  them 
into  jars  of  pure  oxygen,  the  contrast  will  show  how  much  the 
diluent  of  the  air  mitigates  the  violent  action  of  this  gas.  Sulphur 
will  burn  in  the  air  with  a  pale  blue  flame  of  little  luminous  power; 
in  oxygen,  however,  its  flame  is  violet  colored,  emitting  great  light. 

S  +          O2  SO2 

Sulphur.  Sulphur  dioxid. 

A  piece  of  charcoal  with  a  feeble  spark  and  without  flame,  when 
immersed  in  oxygen,  becomes  a  white,  glowing  mass  and  is  in- 
stantly consumed  in  flames.  A  glowing  chip  of  wood  is  a  reagent 
in  testing  for  oxygen  and  the  reaction  is  its  bursting  into  flame. 

C          +          02  C02 

Carbon.  Carbon  dioxid. 

If  a  piece  of  dry  phosphorus  the  size  of  a  pea  be  warmed  in 
a  deflagrating  spoon  and  then  burned  in  oxygen,  its  light  is  of 
insupportable  brilliancy. 

2P         +          50  P2O5 

Phosphorus.  Phosphorus  pentoxid. 

Fine  iron  piano  wire  or  watch  springs  tipped  with  burning  sulphui 
and  set  on  fire  in  oxygen  will  burn  with  dazzling  corruscations. 

3Fe         +         40  Fe304 

froa-  Iron  tetroxid. 


OXYGEN  69 

The  non-metals  burning  in  oxygen  yield  oxids,  which  in  the 
cases  of  sulphur,  carbon,  and  phosphorus  are  gases  that  will  dis- 
solve in  the  water  in  the  jar,  giving  to  it  a  sour  taste  and  an  acid 
reaction.  Iron  forms  a  solid  compound  without  acid  qualities, 
which  leaves  a  rusty  stain  on  the  jar.  Other  metals  form  oxids, 
which  are  usually  bases. 

The  presence  of  free  oxygen  is  revealed  by  adding  to  the  sus- 
pected sample  the  colorless  gas  nitrogen  dioxid,  which  unites  with 
more  oxygen  to  form  red  fumes  of  the  higher  oxids.  Free  oxygen 
is  removed  from  mixtures  of  gases  by  means  of  its  slow  union  with 
phosphorus  or  by  making  use  of  the  absorption  powers  of  a  solu- 
tion of  potassium  pyrogallate. 

Physiologic  Effect.— Oxyhemoglobin  of  the  blood-corpuscles 
under  the  air-pump  yields  about  two  volumes  of  oxygen,  which 
is  so  loosely  associated  as  to  be  separable  without  destruction  of 
the  compound.  This  load  is  readily  transferable  to  oxidizable 
substances.  The  muscles  and,  indeed,  protoplasm  in  general, 
have  the  power  of  absorbing  and  storing  up  oxygen  to  be  utilized 
in  the  transforming  of  chemical  into  other  forms  of  energy.  If 
an  animal  be  enclosed  in  an  atmosphere  containing  no  oxygen 
it  shortly  dies.  It  is  the  only  pure  gas  that  will  sustain  respir- 
ation. At  ordinary  pressures  no  detriment  follows  its  inhalation. 
When  disease  interferes  with  normal  oxygenation  of  the  blood 
benefit  is  obtained  by  enriching  the  air  respired  with  about  60  per 
cent,  of  this  gas.  The  livid  appearance  disappears  under  its 
judicious  employment. 

Uses. — The  gas  is  made  portable  by  condensing  40  gallons  in 
a  small  cylinder.  By  a  rubber  tube  it  is  transmitted  to  a  funnel 
held  near  the  face  of  the  patient.  It  is  used  in  this  way  in  the 
treatment  of  the  later  stages  of  pneumonia  and  consumption  and 
in  resuscitation  from  coal-gas  poisoning. 

Law  of  Chemical  Combination.— When  Priestley,  on  the  dis- 
covery of  oxygen,  resorted  to  the  balance,  he  was  able  to  prove 
that  mercuric  oxid  contains  an  unvarying  amount  of  oxygen  joined 
to  an  unvarying  proportion  of  mercury.  When  the  two  elements 
in  these  fixed  proportions  were  caused  to  combine  they  produced 
the  compound.  Any  excess  of  either  would  not  enter  into  the 
union. 

Potassium  chlorate,  when  analyzed  and  its  constituents  weighed, 
is  found  to  be  composed  of  39  parts  of  potassium,  35.5  parts  of 
chlorin,  and  48  parts  of  oxygen.  All  specimens  of  potassium 
chlorate  have  exactly  this  composition. 

When  the  composition  of  a  salt  is  once  ascertained,  the  knowl- 
edge thus  obtained  applies  to  all  samples  of  that  salt.  Common 


7o 


NON-METALS 


salt    is,    always    and   everywhere,   sodium    23    parts    and   chlorin 

35-5  Parts- 

When  it  is  desired  to  make  note  of  a  chemical  operation  in 

shorthand,  symbols  are  used  to  express  both  the  nature  of  the 
elements  and  the  relative  weights  engaged.  Thus  the  equation, 

KC103=KC1  +  30, 

written  out  in  full,  would  read:  potassium  chlorate  122.5  (potas- 
sium 39  parts,  chlorin  35.5,  and  oxygen  48)  yields  potassium 
chlorid  74.5  (potassium  39,  chlorin  35.5)  and  oxygen  48  parts. 

If  these  figures  on  each  side  of  the  equation  are  added,  they 
will  be  found  to  be  equal,  though  the  =  mark  is  not  used  in  an 
algebraic  sense;  it  means  gives  or  yields. 

Reactions. — We  have  learned  that  mercury,  heated  in  air, 
takes  up  oxygen,  forming  mercuric  oxid,  Hg+O  =  HgO.  This 
is  an  illustration  of  the  first  kind  of  reaction,  called  combination. 
The  second  kind  is  called  decomposition,  as  in  the  case  of  KC1O3, 
given  above,  which  reverses  combination.  The  third  kind  is 
double  decomposition,  when  two  or  more  compounds  break  up 
and  form  two  or  more  others,  thus: 

KC1     +     AgN03     =     AgCl     +     KN03. 

This  is  read,  potassium  chlorid  added  to  silver  nitrate  gives  silver 
chlorid  and  potassium  nitrate. 

When  the  composition  of  many  compounds  is  studied  it  is 
found  that  the  most  satisfactory  unit  for  expressing  the  numeric 
ratios  of  the  combining  weights  is  that  of  hydrogen,  the  lightest 
element.  The  different  symbols  stand,  then,  not  only  for  the  name, 
but  also  for  certain  relative  weights  or  proportions  (H  being  i) 
in  which  the  elements  unite,  or  those  in  which  they  displace  one 
another  in  compounds. 

H  stands  for  i  part  of  hydrogen,  O  for  16  parts  of  oxygen,  O3 
for  3  times  16  or  48  parts  of  oxygen,  K  for  39  parts  of  potassium, 
S  for  32  parts  of  sulphur,  C  for  12  parts  of  carbon. 

A  convenient  statement  of  the  facts  just  referred  to  is  called 
the  law  oj  definite  or  constant  proportions  or  combination: 

"A  definite  chemical  compound  always  contains  the  same 
elements  united  in  the  same  proportions." 

This  law,  first  stated  by  Dalton  in  the  eighteenth  century,  by 
numerous  experiments  became  more  and  more  assured,  and  the 
great  generalization  gradually  took  shape — that  matter  is  inde- 
structible. So  far  as  our  observation  goes,  it  is  not  created,  nor  is 


OXYGEN  71 

it  destroyed.  It  may  change  its  form  a  thousand  times,  but  does 
not  change  its  ultimate  nature,  neither  gaining  nor  losing. 

When  a  piece  of  charcoal  is  burned  in  oxygen  it  disappears 
from  view,  but  if  the  product  contained  in  the  vessel  be  weighed 
it  will  be  found  to  equal  exactly  the  weight  of  the  original 
materials.  The  carbon  has  been  taken  into  an  invisible  gaseous 
compound,  carbon  dioxid.  From  this  state  it  can  be  recovered 
in  the  original  amount  as  fine  black  dust  by  burning  sodium  in 
the  gas.  The  sodium  liberates  the  carbon,  taking  the  oxygen 
away  from  it. 

When  KC1O3  has  yielded  its  oxygen  there  is  left  in  the  retort 
KC1,  potassium  chlorid,  composed  of  potassium  39  parts  and 
chlorin  35.5  parts.  There  is  a  familiar  salt  used  in  medicine, 
potassium  iodid,  which  is  composed  of  potassium  39  parts 
and  iodin  127.  Now  when  chlorin  and  iodin  unite  to  form 
iodin  chlorid,  they  do  so  in  the  same  relative  weight,  35.5  to 
127.  Dependent  upon  facts  of  the  same  character  is  the  corol- 
lary to  the  first  law,  which  is  called  the  law  of  equivalent  pro- 
portions: 

11  The  proportions  in  which  any  two  elements  unite  with  a  third 
are  the  same  in  which  they  unite  with  each  other." 

Hence  it  is  said  that  chlorin  35.5,  iodin  127,  oxygen  16,  sodium 
23,  potassium  39,  are  equivalent  to  each  other,  taking  hydrogen 
as  unity.  Every  element  has  an  assigned  equivalent  weight, 
which  rules  the  proportions  of  its  combinations  with  other 
elements. 

Chemical  Arithmetic. — The  constancy  of  the  proportions  in 
chemical  compounds  definitely  distinguishes  them  from  mechan- 
ical mixtures.  When  active  chemicals  are  mixed  in  any  other  than 
the  exact  proportion,  the  excess  is  inert.  Chemistry  is  based  so 
surely  upon  numeric  laws  that  calculations  can  be  made  for  chem- 
ical operations  as  for  those  of  other  exact  sciences. 

Suppose  the  problem  to  be:  how  much  of  the  gas  would  be 
obtained  by  heating  a  weight  of,  say  250  gm.  (8  oz.,  Troy),  of 
potassium  chlorate.  The  equation,  already  given,  is  as  follows: 

KC103  KC1  +         30. 

From  the  numeric  values  given  for  this  equation  (p.  7°)  we 
calculate  that  122.5  Pafts  of  KC1O3  will,  when  heated,  give  up  48 
parts  of  oxygen.  By  a  sum  in  rule-of-three  (ratio  and  proportion) 
we  easily  find  how  many  would  be  given  by  250  gm.  of  KC1O3: 

122.5    :  25°   ::  4-8   :  x 
#=97.95  gm.  of  oxygen. 


72  NON-METALS 

If  it  be  desired  to  know  the  number  of  liters  represented  by  the 
weight  of  97.95  gm.  an  additional  calculation  is  required.  Experi- 
ments show  that  22.4  L.  of  any  normal  gas  weigh  a  number  of 
grams  equal  to  twice  the  combining  weight.  Then  one-half,  or 
ii. 2  j  would  equal  the  combining  weight,  which,  with  oxygen,  is 
16.  Therefore, 

16   :  97.95    ::   11.2    :  x 

#  =  68.56  L.  of  oxygen  evolved  from  250  gm. 
of  potassium  chlorate. 

Relations  of  Other  Forces  to  Chemical  Energy. — Melting 
solids  by  heat,  or  at  higher  temperatures  vaporizing  them,  favors 
chemical  change.  Furthermore,  all  changes  of  decomposition  or 
of  combination  are  set  in  action  by  the  physical  agencies,  radiant 
energy,  heat,  light,  electricity,  magnetism,  and  mechanical  force. 
These  are  convertible  into  one  another  and  are  but  forms  of  the 
one  energy  in  the  universe. 

When  potassium  chlorate  is  heated  to  a  high  degree  its  par- 
ticles are  freed  from  their  cohesion  and  chemical  action  causes 
the  potassium  and  chlorin  to  form  a  different  compound,  setting 
the  oxygen  free. 

At  ordinary  temperatures  carbon  remains  in  oxygen  for  a  long 
time  without  visible  change,  though  if  coal  be  finely  divided  and 
packed  so  as  to  confine  the  heat  that  is  produced  by  its  gradual 
oxidation,  it  ignites  spontaneously.  Whenever  carbon  is  heated 
to  ignition  there  is  immediate  union  with  the  oxygen.  Moreover, 
the  union  is  itself  attended  by  the  evolution  of  still  more  heat.  In 
the  oxygen  experiments  the  degree  of  heat  is  so  great  that  a  brilliant 
light  is  emitted.  Burning  in  air  is  the  same  as  burning  in  oxygen, 
though  the  visible  heat  is  less  because  the  diluent  nitrogen  in  air 
takes  up  the  heat  without  helping  on  the  process,  while  in  pure 
oxygen  the  chemical  energy  of  that  active  gas  is  increased  by  its 
being  heated.  The  term  combustion  is  applied  to  this  evolution 
of  heat  and  light  by  chemical  action.  Combustion  is  due  to  the 
conversion  of  intrinsic  or  chemical  energy  into  heat  energy.  The 
substances  that  burn  are  called  combustible.  The  process  con- 
verts them  into  incombustible  products,  such  as  carbon  dioxid  and 
sulphur  dioxid.  All  chemical  actions  are  attended  by  changes 
of  temperature,  but  in  writing  equations  it  is  customary  to  omit 
mention  of  the  energy  of  heat  consumed  or  evolved. 
v  The  amount  of  heat  evolved  or  absorbed  in  the  chemical  change 
of  a  substance  is  definite  and  is  always  the  same  from  given  weights 
of  the  reagents.  If  rapid  union  be  induced,  as  in  combustion, 
then  a  higher  temperature  is  noted,  but  no  more  heat  in  quantity 
is  given  off  than  when  union  is  gradual.  The  number  of  heat 


OXYGEN  73 

units  or  calories  (p.  34)  obtained  is  the  same  whether  combustible 
bodies  are  oxidized  by  degrees  or  whether  the  same  substances  are 
burnt  up.  When  coal  is  burned  in  a  grate  we  have  an  example  of 
heat  production  by  quick  oxidation.  When  carbon  compounds 
are  consumed  in  our  bodies  by  their  union  with  the  oxygen  of  the 
blood  obtained  from  respired  air,  we  have  an  instance  of  heat  «- 
production  by  slow  oxidation.  A  given  weight  of  the  combustible 
will  yield  the  same  number  of  heat  units  in  both  cases.  One  gram 
of  a  carbohydrate,  such  as  starch,  burned  with  oxygen  in  a  calor-  - 
imeter,  liberates  4100  calories.  In  the  animal  body  the  same 
weight  of  starch  is  oxidized  to  the  same  products  (carbon  dioxid 
and  water),  liberating  the  same  number  of  calories.  Combustion 
means  that  the  heat  is  given  off  in  a  short  period,  evincing  great 
intensity.  The  process  has  high  velocity.  Oxidation  in  the  animal 
body  is  distributed  through  greater  periods  and  regulated  so  that 
the  escape  of  heat  is  compatible  with  life;  indeed,  is  necessary  to  it. 
It  is  dissipated  as  fast  as  it  is  produced.  The  velocity  is  so  low 
that  the  heat  never  reaches  sufficient  intensity  to  ignite  the  elements 
engaged. 

To  use  a  homely  illustration:  if  a  bucket  slowly  leaks,  a  gallon 
of  water  can  be  poured  into  it  at  the  same  rate  (slow  oxidation) 
and  no  water  accumulates,  but  if  poured  quickly  (combustion) 
the  water  level  rises,  stands  high  in  the  bucket,  and  may  even 
overflow.  Two-thirds  of  the  amount  of  heat  generated  in  the 
body  is  converted  to  other  forms  of  energy  and  escapes  by  radiation,  ^ 
the  remaining  one-third  finds  outlets  in  the  hot  urine  and  feces, 
which  contain  much  more  heat  than  the  cool  water  drunk;  in  the 
latent  heat  of  vaporizing  the  water  of  perspiration  and  respira- 
tion; and  in  warming  the  air  inhaled,  which  has  high  specific 
heat  (p.  34). 

The  Heat  of  Decomposition.— The  heat  consumed  in 
slowly  oxidizing  mercury  to  form  mercuric  oxid  is  the  same  in 
amount  as  that  required  to  decompose  it  into  its  elements.  To 
form  HgO  it  takes  30,660  calories,  and  to  separate  its  elements 
Hg  and  O  the  same  number  of  heat  units  must  be  used. 

Work=energy  of  Oxidation.— Heat  is  a  source  of  mechan- 
ical motion,  as  in  the  steam  engine,  and,  on  the  other  hand,  the 
arrest  of  motion  causes  heat.  They  are  reciprocally  convertible 
in  definite  amounts,  a  certain  amount  of  work-energy  producing 
a  corresponding  amount  of  heat-energy  and  vice  versa.  This 
numeric  relationship  is  expressed  thus:  one  calorie  equals  0.426-* 
kilogram-meters,  which  is  to  say,  that  the  amount  of  heat  required 
to  warm  one  gram  of  water  one  degree  Centigrade  of  temperature 
will,  when  converted  to  work-energy,  lift  i  kilogram  weight  through 
0.426  meters. 


74  NON-METALS 

In  order  to  have  but  one  unit  for  all  the  different  forms  of  energy, 
that  of  Joule  has  been  chosen.  Thus  i  calorie  (cal.)  equals  4.18 
joules  (j.),  or,  reversing  the  statement,  i  joule  =  0.239  cal. 

Large  amounts  of  energy  are  expressed  by  kilo  joules  (kj.)  or 
1000  joules.  By  experiment  it  is  found  that  the  heat  of  combustion 
of  a  combining  weight  of  carbon  equals  that  which  produces 
406  kj.  of  work-energy.  The  equation  C  +  O2=CO2  +  4o6  kj. 
reads  thus:  the  sum  of  the  intrinsic  energy  of  12  gm.  of  carbon 
and  32  gm.  of  oxygen  equals  the  energy  of  44  gm.  of  carbon  dioxid 
plus  406  kj.  This  406  kj.  may  be  utilized  in  engines  suited  for 
converting  heat  to  motion,  or  in  animals  for  maintaining  the  work- 
energy  and  animal  heat.  The  energy  of  CO2,  an  incombustible 
product,  is  less  than  that  of  the  combustible  C  and  O  by  406  kj. 
Hence  to  restore  CO2  to  the  original  state  of  free  C  and  free  O  this 
energy  must  be  supplied.  In  nature  the  source  of  this  energy  is  the 
sun,  which,  acting  upon  the  leaves  of  plants  as  its  instruments, 
breaks  up  the  CO2  of  the  air,  storing  C  in  the  plant  and  giving 
O  back  to  the  air. 

OZONE  OR  ALLOTROPIC  OXYGEN 

Symbol,  O3.     Molecular  weight,  48. 

When  the  sparks  of  an  electric  machine  are  passed  through 
dry  air  or  oxygen  a  peculiar  odor  is  developed.  This  odor  has 
been  observed  after  thunder-storms  or  when  flint  and  steel  are 
struck.  The  odoriferous  substance  is  named  ozone  (Greek, 
ozein,  to  smell). 

Occurrence. — Owing  to  its  odor,  ozone  can  be  recognized  in 
the  air  when  present  in  the  proportion  of  only  one  part  to  a  hun- 
dred thousand.  Delicate  tests  detect  it  in  sea  air,  at  the  seashore, 
where  water  evaporates  from  sand  and  where  the  waves  are  broken 
into  spray;  in  the  country,  and  especially  in  the  air  of  pine  forests. 
On  the  windward  side  of  cities  it  can  be  found,  but  all  trace  dis- 
appears on  the  leeward  side.  The  organic  impurities  emanating 
from  cities  destroy  the  ozone. 

Preparation. — Ozone  can  be  produced  by  slowly  oxidizing 
phosphorus  in  moist  air.  A  stick  of  phosphorus,  freshly  scraped, 
is  put  in  a  wide-mouthed  bottle  of  air  or  oxygen  and  half  covered 
with  water.  The  bottle  is  closed  for  an  hour  or  two,  when,  at  the 
end  of  that  time,  the  ozone  is  present. 

Another  method  is  by  adding  2  parts  of  potassium  perman- 
ganate to  3  parts  of  sulphuric  acid. 

Siemen's  induction  tube  generates  ozone  by  discharging  elec- 
tricity silently  through  an  atmosphere  of  dry  oxygen.  A  tube  of 
glass  covered  with  tinfoil,  like  the  outer  coat  of  a  Leyden  jar,  encloses 


OZONE    OR    ALLOTROPIC    OXYGEN 


75 


the  space  to  be  filled  with  oxygen.  In  the  axis  of  this  tube  is 
another,  smaller  and  lined  inside  with  tinfoil  like  the  inner  coat 
of  a  Leyden  jar.  The  dry  oxygen  slowly  traverses  the  space 
between  the  tubes,  while  the  electric 
discharge  from  either  a  friction  ma- 
chine or  an  induction  coil  passes 
invisibly  from  the  tinfoil  on  one  tube, 
through  the  glass  and  oxygen,  to  the 
tinfoil  on  the  other  tube.  In  its 
transit  a  portion  of  the  odorless  oxy- 
gen acquires  the  odor  of  ozone  and 
will  oxidize  substances  that  resist  the 
pure  oxygen. 

Instead  of  tinfoil  as  a  condenser, 
sulphuric  acid  is  used  in  the  appa- 
ratus shown  in  Fig.  24.  A  tall  glass 
cylinder  containing  sulphuric  acid  has 
immersed  in  it  a  bent  tube  having 
one  limb  larger  than  the  other. 
The  wider  limb  has  an  inner  tube 
containing  sulphuric  acid.  Elec- 
trodes of  platinum  dip  into  the  sul- 
phuric acid,  inside  and  outside. 
While  an  induction  coil  discharges 
between  the  electrodes,  dry  oxygen  (O2)  passes  in  at  a  and  comes 
out  ozonized  (O3)  at  b. 

If  ozone  be  passed  into  a  solution  of  potassium  iodid,  the  iodin 
is  liberated  and  potassium  hydroxid  formed: 


FIG.  24. — Ozone  generator. 


2KI 

Potassium 
iodid. 


H20     +      03     =      2KOH     -f     I2 

Ozone.  Potassium  Iodin. 

hydroxid. 


02 

Oxygen. 


The  least  trace  of  free  iodin  can  be  detected  by  a  solution  of 
starch,  which  will  turn  a  deep  blue  color.  Sch&nbein's  test-paper 
is  made  by  saturating  pieces  of  white  filter-paper  with  a  mixture 
of  solutions  of  starch  and  potassium  iodid.  If  dried  and  kept  in 
tight  bottles,  this  paper  is  a  ready  test  for  ozone  in  the  air.  To 
use  it,  the  paper  must  be  moistened  with  distilled  water  and  sus- 
pended in  an  exposed  place  to  the  current  of  air  to  be  tested. 
This  test  is  liable  to  a  fallacy  from  the  fact  that  when  either  chlorin 
or  nitrogen  tetroxid  is  present  iodin  is  liberated  and  the  same 
color  reaction  ensues.  Ozone,  however,  is  peculiar  in  yielding 
the  alkali  potassium  hydroxid,  or  KOH,  of  the  equation  given 
above.  It  is  an  improvement  on  Schbnbein's  method  to  apply 
litmus  instead  of  starch  to  prove  that  the  potassium  iodid  has 


76  NON-METALS 

been  decomposed  by  ozone.  A  solution  of  potassium  iodid  col- 
ored with  a  reddish-violet  litmus  and  exposed  in  a  shallow  white 
dish  for  several  hours  will  detect  ozone  in  the  air  very  readily. 
A  control  experiment  should  be  conducted  with  the  portion  of 
the  same  litmus  solution  without  the  iodid.  Another  convenient 
method  is  to  expose  violet  litmus-paper  moistened  with  a  solution 
of  potassium  iodid.  If  ozone  be  present,  this  test-paper  will  be 
turned  blue  from  the  alkaline  hydroxid;  but  the  same  paper  wet 
with  distilled  water  will  be  unaffected. 

Properties. — Ozone  as  a  gas  is  colorless,  having  an  odor  like 
that  of  chlorin.  It  has  been  liquefied  at  —105°  C.  (—157°  F.), 
with  a  pressure  of  125  atmospheres,  and  is  then  of  blue  color. 
As  ordinarily  dealt  with,  it  is  always  largely  diluted  with  oxygen. 
In  the  dry  state  it  can  be  kept  unchanged,  though  its  intrinsic 
energy  gives  it  a  tendency  to  explode  into  the  state  of  ordinary 
oxygen,  developing  heat.  At  a  temperature  of  250°  C.  (482°  F.) 
it  is  reconverted  into  oxygen.  It  is  soluble  in  turpentine  and 
sparingly  so  in  water. 

Its  chief  chemical  attribute  is  that  of  an  oxidizing  agent.  By 
it  elementary  phosphorus,  sulphur,  and  arsenic  are  oxidized  to 
acids,  and  ammonia  to  nitric  acid.  Metals  that  do  not  rust  in 
the  air,  such  as  mercury  and  silver,  soon  lose  their  brilliancy  in 
ozone.  Only  gold  and  the  members  of  the  platinum  group  resist  it. 

Paper  made  black  with  lead  sulphid  becomes  white,  the  ozone 
changing  the  sulphid,  PbS,  to  the  white  sulphate,  PbSO4. 
Organic  substances,  such  as  cork  and  rubber,  are  corroded  by  it; 
organic  colors  are  bleached  and  gases  of  foul  odor  decomposed. 
It  is  a  strong  irritant  to  the  air-passages,  causing  acute  catarrhal 
symptoms  even  when  the  air  contains  so  small  an  amount  as  7 
parts  in  the  100,000. 

Nature  of  Ozone. — When  oxygen  is  ozonized  by  exposure 
to  electric  discharges  its  volume  is  diminished  and  its  density 
increased  without  the  application  of  cold  or  heat,  but  when  the 
ozone  is  heated  to  250°  C.  (482°  F.)  it  regains  its  volume  while 
losing  its  characteristics  as  ozone.  Three  volumes  of  oxygen  are 
condensed  to  form  two  of  ozone;  hence  it  is  sometimes  called 
condensed  oxygen  or  allotropic  oxygen. 

Allotropism. — When  an  element  presents  itself  in  two  or  more 
different  modifications,  the  property  is  termed  allotropism.  There 
are  allotropic  forms  of  oxygen,  sulphur,  phosphorus,  carbon,  iron, 
etc.  To  explain  the  fact  of  condensation  when  oxygen  takes  the 
form  of  ozone  resort  is  had  to  the  theory  of  the  molecular  con- 
stitution of  matter.  Matter  is  assumed  to  be  composed  of  small 
separate  particles  called  molecules,  which  are  usually  groups  of 
two  or  more  smaller  particles,  called  atoms.  Many  facts  sustain 


HYDROGEN  77 

the  law  oj  Avogadro:  "Equal  volumes  of  elementary  gases  contain 
an  equal  number  of  molecules."  The  condensation  of  three 
volumes  of  oxygen  to  two  of  ozone  is  then  accounted  for  by  assuming 
that  in  an  equal  volume  the  ozone  contains  one-third  more  atoms, 
which  must  be  accommodated  in  the  equal  number  of  molecules 
by  making  the  molecules  heavier.  If  the  molecule  of  oxygen  is 
symbolized  by  O2,  then  that  of  ozone  becomes  O3.  Three  mole- 
cules of  oxygen  then  contain  six  atoms  in  three  groups  of  two  each. 
When  they  change  to  two  molecules  of  ozone,  they  contain  the 
same  number  of  atoms,  but  in  two  groups,  containing  three  atoms 
each,  3O2  =  2O3. 

Carbon  dioxid  is  produced  when  carbon  is  burned,  whether  in 
oxygen  or  ozone,  but  the  number  of  the  calories  produced  is  very 
different  in  the  two  cases.  More  heat  is  given  off  by  combustion 
in  ozone  than  in  oxygen — proof  that  the  molecule  of  ozone  has 
more  intrinsic  energy.  Stated  as  an  equation:  Ozone  =  oxygen  + 
energy.  Allotropic  elements  may  be  regarded  as  those  which 
under  varying  conditions  take  up  different  amounts  of  energy  and 
thereby  show  a  difference  of  properties. 

In  the  equation  below  the  facts  are  represented  on  the  theory 
of  molecules  and  atoms: 

03    -ji>     O,     +     O     +     32,900  cal.  (137  kj). 

The  O3  represents  molecular  ozone  which  yields  O2,  one  molecule 
of  ordinary  oxygen,  and  O,  one  atom  uncombined,  said  to  be 
nascent  oxygen,  which  has  an  extraordinary  readiness  for  a  chem- 
ical union.  In  terms  of  the  molecular  theory  allotropism  is  the 
property  of  an  element,  under  different  circumstances,  to  appear 
in  molecules  which  have  a  difference  in  their  atomic  constitution. 

HYDROGEN 

Symbol,  H.     Atomic  weight,  i.oi. 

Occurrence. — Hydrogen  exists  free  in  the  gaseous  emanations 
from  volcanoes,  certain  mines,  "natural  gas,"  and  petroleum 
wells.  As  a  product  of  fermentation  of  organic  matter  it  is  found 
in  gastric  and  intestinal  flatus.  Its  peculiar  "lines"  are  seen  in 
the  spectra  of  the  sun  and  various  stars. 

Combined  with  other  elements,  hydrogen  is  exceedingly  abun- 
dant. With  oxygen  it  forms  one-ninth  of  the  weight  of  all  the 
water  on  the  globe;  with  nitrogen  it  is  present  in  the  air  as  ammonia; 
with  sulphur  it  makes  the  gas  hydrogen  sulphid,  present  in  sulphur 
waters.  In  organic  nature  it  occurs  not  only  in  the  hydrocarbons 
and  the  carbohydrates,  but  in  almost  all  animal  and  vegetable 
substances. 


NON-METALS 


Preparation.—  i.  By  Electrolysis.—  If  a  current  of  electricity 
be  passed  through  water  by  means  of  platinum  electrodes  pure 
hydrogen  bubbles  off  at  the  negative  pole  and  oxygen  at  the 
positive,  two  volumes  of  the  former  to  one  of  the  latter  (Fig.  25). 
The  hydrogen  is  identified  by  its  taking  fire  when  lighted,  the 
oxygen  by  its  causing  a  glowing  splinter  of  wood  to  burst  into 
flame.  The  current  is  usually  obtained  from  a  battery  of  five  or 
more  galvanic  cells  —  a  combination  of  zinc  and  carbon  plates 
immersed  in  a  liquid  that  acts  upon  the  zinc.  The  chemical 
action  in  the  battery  is  transformed  into  electricity,  which  is  trans- 
mitted by  the  conductors  to  the  apparatus  for  electric  decom- 
position. The  process  of  separation  of  the  constituents  of  a  com- 
pound by  electricity  is  known  as  electrolysis. 
By  means  of  this  process  the  most  obstinate 
compounds  have  been  resolved  into  their 
elements  under  the  conditions  stated  on  p.  50. 
The  substance  must  be  a  conductor  of 
electricity  —  i.  e.,  an  electrolyte.  Pure  water 
possesses  this  property  in  such  an  exceedingly 
small  degree  that  it  is  regarded  as  a  non-con- 
ductor. Its  conductivity  is  improved  by 
adding  to  it  one-fourth  part  of  sulphuric  acid, 
which  furnishes  the  ions  necessary  for  con- 
ducting the  current. 

2.  By  the  Action  of  Various  Metals  on 
Water.  —  The  affinity  of  metals  for  oxygen 
can  be  used  in  the  decomposition  of  water 


FIG.  25. —  Apparatus 
for  the  electrolytic  decom- 
position of  water,  yield- 
ing hydrogen  and  oxygen 
separately. 


FIG.  26.— Potassium  decomposing  water. 


for  liberating  hydrogen.  Most  metals  act  very  slowly  at  ordinary 
temperature,  but  potassium  and  sodium  decompose  water  very 
promptly.  They  unite  with  oxygen  with  such  violence  that  the 
free  hydrogen  is  inflamed.  A  piece  of  potassium  or  sodium  the 
size  of  a  pea  thrown  upon  water  will  float  about  (Fig.  26),  first 
melting  into  a  silvery  globule,  hissing  hot,  then  glowing,  and 
finally  igniting  the  free  hydrogen.  If  the  water  has  been  tinctured 
with  red  litmus,  it  will  turn  blue  from  the  formation  of  sodium 
hydroxid. 

H2O     +     Na  NaHO      +     H. 

Sodium.          Sodium  hydroxid. 


HYDROGEN  79 

In  order  to  collect  the  hydrogen  unignited  a  test-tube  or  glass 
cylinder  should  be  filled  with  water  and  inverted  with  the  open 
end  immersed  in  a  trough  of  water.  Small  pieces  of  sodium 
wrapped  in  filter-paper  can  then  be  held  by  forceps  underneath 
the  mouth  of  the  test-tube.  The  gas  is  given  off  and  collects  above 
the  surface  of  the  water,  forcing  the  water  out  of  the  tube.  To 


FIG.  27.— Hydrogen  disengaged  from  water  by  sodium. 

prevent  explosions  the  sodium  should  be  cut  into  pieces  no  larger 
than  a  split  pea.  In  Fig.  27  the  sodium  is  held  under  water  by 
a  wire-gauze  spoon  which  permits  the  gas  to  rise  into  the  cylinder. 

3.  To  get  hydrogen  for  manufacturing  purposes  on  a  large 
scale  the  affinity  of  iron  for  oxygen  is  utilized.      Here  high  heat  is 
required.    Steam  is  passed  over  iron  turnings  heated  to  redness  in 
an  iron  tube. 

3Fe     +     4H20     =     Fe304     +     4H2 

Iron.  Water.  Iron  tetroxid.          Hydrogen. 

The  iron  is  oxidized  to  the  tetroxid  and  the  hydrogen  passes 
out  to  the  collecting  apparatus.  If  charcoal  be  used  instead  of 
iron  at  a  high  heat,  a  gas,  carbon  monoxid,  is  formed,  and  the 
two  gases  can  be  utilized  as  sources  of  heat  and  light. 

C       +       H20       =       CO       +       H2. 

Carbon  monoxid. 

4.  Hydrogen  for  the  laboratory  is  customarily  prepared  by 
the  reaction  of  some  acid  upon  a  metal.     The  acids  all  contain 
hydrogen  and  have  the  common  characteristic  of  giving  it  up 
easily,  taking  a  metal  in  exchange.     The  most  convenient  materials 
are  zinc  and  dilute  sulphuric  acid. 

Zn     +     H2SO4     =     ZnSO4     +     H2. 

Zinc.  Acid  sulphuric.         Zinc  sulphate. 


8o 


NON-METALS 


Zinc  sulphate  remains  in  solution,  and  the  hydrogen  is  set  free. 
If  hydrochloric  acid  be  used,  then 

Zn       +        2HC1        =        ZnCl2        +        H2. 

Acid  hydrochloric.  Zinc  chlorid. 

These  reactions  are  illustrations  of  substitution.  The  zinc  is 
substituted  for  the  hydrogen,  and  there  is  a  new  arrangement  of 
the  elements  (Fig.  28). 

To  perform  this  operation  the  zinc,  in  small  pieces,  is  put  into 
a  glass  flask  or  two-necked  bottle.  The  stoppers  of  rubber  or 
cork  are  perforated  for  tubes.  One  has  a  funnel  outside,  the 
lower  end  reaching  nearly  to  the  bottom  of  the  flask.  The  other 
tube  is  short  within  the  flask  and  bent  outside  at  an  angle  con- 
venient for  the  attachment  of  a  delivery  tube.  When  the  appa- 
ratus is  tightly  closed  the  sulphuric  acid,  diluted  with  five  to  six 


FIG.  28.— Hydrogen  generator. 

parts  of  water,  is  poured  through  the  funnel  tube  and  a  brisk 
effervescence  begins  immediately.  The  gas  bubbles  through  the 
water  of  the  pneumatic  trough  and  collects  in  jars  prepared  for 
receiving  it. 

Precaution. — Before  collecting,  it  is  advisable  to  allow  suffi- 
cient gas  to  escape  to  be  sure  that  the  air  has  all  been  expelled 
from  the  collecting  jars,  otherwise  an  inflammable  mixture  is 
formed  which,  when  ignited,  explodes  with  dangerous  violence. 
The  test  for  this  consists  in  obtaining  a  sample  of  the  hydrogen 
at  the  trough  by  inserting  a  water-filled  test-tube  over  the  escaping 
bubbles.  Pure  hydrogen  burns  quietly  at  the  mouth  of  the  tube 
held  mouth  downward,  while  the  occurrence  of  a  slight  explosion 
proves  that  some  air  still  remains.1 

Physical  Properties.— Hydrogen  is  the  lightest    known    sub- 

1  Prepared  in  this  way  from  common  zinc  the  gas  always  has  an  odor,  due  to  the 
formation  of  gaseous  compounds  of  hydrogen  with  arsenic  and  phosphorus  present 
in  the  impure  zinc,  or  to  hydrogen  sulphid  when  hot  acid  is  used,  or  to  nitrous  and 
nitric  oxids  when  the  acid  contains  some  nitric  acid. 


HYDROGEN 


8l 


stance,  being  14.47  times  lighter  than  air.  Its  specific  gravity 
is  0.06926  (air=i),  and  i  liter  weighs  0.0899  gm-  It  is  trans- 
parent, colorless,  odorless,  and  tasteless.  It  is  not  poisonous,  but 
will  not  support  life.  If  permitted  to  escape  from  a  pressure  of 
1 80  atmospheres  at  —205°  C.  (  —  337°  F.)  it  is  a  colorless,  clear 
liquid,  which  freezes  by  its  own  evaporation,  reaching  a  temper- 
ature of  —258°  C.  (  —  432.4°  F.).  It  is  nearly  insoluble  in  water. 
It  conducts  heat  and  electricity  better  than  any  other  gas.  It  is 
the  most  highly  diffusible  of  gases,  passing  through  a  porous 
medium  four  times  more  rapidly  than  oxygen.  Gas-bags  of  rubber, 
leather,  membrane,  or  other  porous  material  permit  this  diffusion 
with  such  freedom  that  in  a  short  time  the  contents  of  the  bag 
become  an  explosive  mixture,  consisting  of  hydrogen  and  oxygen 
obtained  from  the  air. 

If  the  metal  palladium  is  used  as  the  negative  electrode  in  the 
electrolysis  of  water,  980  volumes  of  hydrogen  will  be  retained  by 
it.  By  applying  heat  the  metal  gives  up  this  occluded  gas  in  a  very 
active  condition,  similar  to  the  state  of  hydrogen  just  free  from 
chemical  combination. 

Chemical  Properties.— While  hydrogen  and  oxygen  resem- 
ble one  another  in  physical  properties,  chemically  they  are  oppo- 
sites  and  have  a  great  attraction  for  one  another.  Hydrogen, 
however,  is  unique  in  its  affin- 
ities, resembling  the  metals 
more  than  the  non-metals, 
combining  with  chlorin,  ni- 
trogen, sulphur,  and  carbon. 
It  does  not  support  combus- 
tion, but  burns  with  a  non- 
luminous  blue  flame,  hotter 
than  that  produced  by  any 
other  burning  substance  in 
equal  weight.  In  combus- 
tion two  volumes  of  it  unite 
with  one  volume  of  oxygen 
to  form  two  volumes  of 
water  vapor.  If  the  gas  be 
dried,  by  passing  it  through 
a  desiccating  tube,  and  then 
ignited  at  the  terminal  jet 
(Fig.  29),  it  burns  with  a  pale 

flame,       depositing       moisture  FIG.  29.- Water  formed  by  burning  hydrogen. 

on  the  glass  bell-jar.     Mixed 

with  chlorin,  hydrogen  explodes  in  the  sunlight;  with  oxygen  it 

explodes  violently  by  the  touch  of  a  flame  or  an  electric  spark. 


82  NON-METALS 

In  the  oxyhydrogen  blowpipe  a  blast  of  oxygen  is  blown  through 
the  hydrogen  flame;  at  its  temperature  of  2000°  C.  (3632°  F.) 
quartz  and  ruby  are  fused.  The  lime  light  for  stereopticons  is 
made  by  heating  lime  in  it  to  incandescence. 

Hydrogen  is  a  reducing  or  deoxidizing  agent.  That  is  to  say, 
it  will  take  oxygen  from  oxids,  reducing  them  to  lower  oxids  or 
to  the  metallic  state.  Copper  oxid  or  iron  oxid  at  a  red  heat  in 
a  stream  of  hydrogen  parts  with  the  oxygen,  forming  water  and 
the  free  metal: 

Fe304         +         4H2  4H20         +         3Fe. 

Reversible  Processes. — Red-hot  iron  oxidizes  in  steam;  the 
water  giving  oxygen  to  the  iron  is  reduced  to  hydrogen.  On 
the  other  hand,  to  produce  the  purest  form  of  iron,  such  as  is  used 
in  medicine  under  the  name  reduced  iron,  hydrogen  is  passed  over 
red-hot  iron  oxid  (p.  79).  This  mutual  play,  by  which  substi- 
tution and  reformation  can  be  made  to  occur  at  will,  is  expressed 
in  an  equation  which  can  be  read  either  way,  the  double  arrow 
meaning  that  it  is  reversible: 

water     +     iron     ~*-Z-     hydrogen     +     iron  oxid. 

In  any  chemical  process  we  must  consider  not  only  the  affinities 
and  the  temperature  of  the  substances,  but  also  another  influence, 
the  active  mass  or  concentration,  or,  to  state  it  more  accurately,  the 
ratio  of  substances  present.  If  the  amount  of  hydrogen  is  rel- 
atively large  the  equation  should  read  from  right  to  left,  but  if 
the  ratio  of  water  vapor  predominates  in  amount  the  reading  is 
reversed.  To  use  a  homely  illustration:  a  man  may  carry  a  pail 
of  water,  but  a  flood  of  water  will  carry  away  the  man. 

Mass-action. — This  is  defined  as  that  effect  upon  the  chemical 
interaction  of  substances  due  to  their  relative  masses, — /.  e.,  to  their 
concentrations  present. 

When  the  operation  is  conducted  in  an  apparatus  that  does  not 
permit  the  escape  of  the  hydrogen  nor  the  condensation  of  steam 
to  water,  the  point  at  which  the  oxidation  of  iron  by  water  vapor 
comes  to  a  halt  is  when  a  definite  ratio  is  reached  between  the 
hydrogen  and  the  water  vapor  present.  This  ratio  is  the  same  as 
that  established  by  the  reverse  process  of  reducing  iron  oxid  by 
hydrogen  (Fig.  30,  c). 

Chemical  equilibrium  is  the  state  of  balance  caused  when  two 
opposing  tendencies  equalize  each  other.  Such  a  mutual  check 
obtains  in  all  chemical  processes,  although  in  many  the  balanced 
concentrations  of  some  of  the  substances  engaged  are  so  small  as  not 


WATER 


to  be  noticed,  the  observer  detecting  the  movement  in  one  direction 
only  (pp.  37,  43,  aad  134). 

The  usual  terms  employed  to  describe  a  chemical  reaction  are 
based  upon  the  theory  of  an  impelling  force  causing  one  element 
to  drive  another  out.  It  is  more  satisfactory  to  discover  the  posi- 
tion of  equilibrium  by  calculating  the  ratios  of  opposed  forces 
and  then  state  them  as  relative  velocities.  When  the  velocities  of 
two  opposite  reactions  are  equal,  so  that  in  a  unit  of  time  each  acts 
as  much  as  the  other,  we  have  the  condition  of  equilibrium.  In  the 
diagram  (Fig.  30)  it  is  shown  that  the  point  of  equilibrium  may  be 


86* 


Formation  of  ethyl 
acetate. 


Reduction  of  FeaO4. 


Maltose  changing  to 

glucose  (p.  439). 

FIG.  30.— Equilibrium  of  opposing  reactions;  the  vigor  is  indicated  by  the  height  of  the  lines  D  and  F, 
and  the  velocities  by  the  arrows. 

attained   at   different   degrees   of   concentration   of   the   materials, 
dependent  on  the  initial  vigor  of  the  two  reactions. 

The  velocities  are  indicated  by  the  length  of  the  arrows.  The 
balls  rolling  down  the  inclines  show  at  E,  the  point  of  rest  when 
chemical  change  ceases,  leaving  some  of  the  original  factors  present 
with  the  new  products.  In  b  is  shown  acetic  acid  acting  on  ethyl 
alcohol  at  D,  producing  ethyl  acetate  and  water  at  F  (p.  433). 
The  change  ceases  when  67  per  cent,  of  the  material  has  been  trans- 
formed. The  ester  formation  is  represented  by  the  motion  along 
DE,  the  reverse  hydrolysis  by  FE. 

WATER 
Formula  H2O.     Molecular  weight,  18. 

Occurrence. — In  nature  it  exists  as  a  solid  in  snow  and  ice;  as 
a  liquid  it  forms  lakes,  rivers,  and  seas;  suspended  in  the  air  as 
minute  liquid  particles  it  forms  the  clouds  and  fog;  as  a  colorless 
gas  it  is  a  constituent  of  the  atmosphere.  It  comprises  three- 
fourths  or  four-fifths  of  the  substance  of  plants  and  animals,  and 
is  found  in  various  minerals,  as  water  of  hydration  or  of  crystal- 
lization,  where  it  is  indicated  by  the  sign  of  a  comma  before  H2O, 
as  in  the  formula  for  sodium  carbonate:  Na2CO3,ioH2O.  The 
water  thus  combined  in  crystals  is  in  definite  proportions,  is 
always  necessary  to  their  form,  and  often  to  their  color,  but  does 
not  affect  their  chemical  relations.  A  crystal  which,  like  sodium 
carbonate,  gives  off  this  water  spontaneously  is  said  to  effloresce. 


g4  NON-METALS 

Salts  which,  like  calcium  chlorid,  absorb  water  from  the  air 
and  dissolve  are  said  to  deliquesce,  thereby  forming  hydrates. 

A  solid  hydrate  when  heated  loses  its  water  and  crumbles  into 
the  exsiccated  form  without  losing  its  chemical  properties. 

Formation.— It  has  been  stated  before  that  by  electrolysis  of 
water  two  volumes  of  hydrogen  are  evolved  at  the  negative  elec- 
trode and  one  volume  of  oxygen  at  the  positive.  If  these  three 
volumes  be  introduced  into  an  eudiometer1  (Fig.  31),  they  will 
explode  by  a  spark  and  unite  to  form  two  volumes  of  the  vapor 
of  water  when  measured  at  100°  C.  (212°  F.). 


A  B  C 

FIG.  31. — A,  Battery;  5,  electrolytic  cell;  C,  mixed  gases,  explosive. 

Physical  Properties. — Without  taste  or  odor,  water  appears 
colorless  in  ordinary  vessels,  but  it  is  bluish  green  when  observed 
in  layers  several  yards  in  thickness.  Its  freezing-point  is  o°  C. 
(32°  F.),  its  boiling-point  100°  C.  (212°  F.).  It  is  a  poor  con- 
ductor of  heat,  but  may  be  heated  readily  in  masses  from  below 
through  the  circulation  of  convection  currents.  It  contracts  when 
cooled  until  the  temperature  is  lowered  to  4°  C.  (39.2°  F.),  at 
which  point  it  reaches  its  maximum  density.  This  property  is  the 
opposite  of  that  possessed  by  most  substances,  where  the  with- 
drawal of  heat  means  contraction  indefinitely.  From  4°  C. 
(39°  F.)  down  to  o°  C.  (32°  F.)  water  expands  as  it  cools  (one 
volume  becoming  1+0.00012).  In  freezing  as  ice  it  becomes 
specifically  lighter  and  floats  on  the  liquid  water.  This  explains 
the  fortunate  circumstance  that  lakes,  rivers,  and  seas  in  cold 
latitudes  do  not  freeze  solid  from  the  bottom  up.  Under  the 
surface-ice  the  water  keeps  at  a  temperature  compatible  with  the 
life  of  the  aquatic  inhabitants.  Winds  cool  the  surface-water, 
which,  becoming  heavier,  sinks,  and  lighter  and  warmer  water 
rises  to  its  place.  This  goes  on  until  the  whole  is  reduced  to  4°  C. 
(39.2°  F.),  and  then  the  surface-water  no  longer  sinks.  Ice  is 

1  An  eudiometer  is  an  instrument- for  analyzing  gases  by  exploding  out  the  hydro- 
gen with  oxygen,  or  vice  versa,  and  measuring  the  calm  gases  left. 


WATER  85 

formed  only  at  the  top,  the  mass  of  water  retaining  a  temperature 
of  4°  C.  (39.2°  F.).  If  water  became  heavier  as  it  cooled  down 
to  the  freezing-point,  a  continual  circulation  would  be  kept  up 
until  the  mass  was  cooled  to  o°  C.  (32°  F.),  when  solidification  of 
the  whole  would  take  place. 

Most  of  the  soluble  solids  dissolve  in  water.  Being  neutral, 
it  takes  on  the  properties  of  dissolved  substances  in  odor,  color, 
taste,  or  chemical  reaction,  acting  simply  as  a  vehicle.  Natural 
waters  vary  in  the  character  and  amount  of  these  constituents 
because  of  the  difference  in  the  rocks  and  soils  from  which  they 
have  been  extracted.  Beyond  a  certain  proportion  the  minerals 
give  it  an  unwholesome  quality,  and  then  the  water  is  not  con- 
sidered potable,  but  is  called  a  mineral  water.  If  it  be  highly 
charged  with  gases,  it  is  said  to  be  effervescent.  Sulphur  water 
contains  the  gas  hydrogen  sulphid.  Chalybeate  waters  have  iron 
salts  in  solution  (p.  256). 

Natural  water  is  never  chemically  pure:  even  in  the  cloud  or 
rain-drop  it  has  taken  up  gases  or  dust  from  the  atmosphere.  By 
the  term  aqua  (U.  S.  P.)  is  meant  the  purest  attainable  in  a  natural 
state.  To  get  it  free  from  impurity  it  must  be  distilled. 

Distillation. — It  is  first  changed  into  steam  by  heat  and  then 
the  steam  is  cooled  again  until  it  condenses  to  liquid  water.  The 
impurities  that  are  not  volatile  are  left  behind.  The  operation 
may  be  conducted  in  the  condenser  shown  in  Fig.  77.  A  current 
of  cold  water  circulates  in  an  outer  jacket  around  an  inner  tube 
for  steam.  The  hot  vapor  flowing  down  loses  its  heat  to  the  cold 
water  streaming  up,  which  absorbs  it,  the  two  opposing  currents 
tending  to  an  equilibrium  of  temperature. 

Sublimation. — When  the  distilled  substance  is  a  crude  solid 
like  native  "  brimstone,"  which  is  recovered  as  a  purified  solid 
like  sulphur,  the  substance  vaporized  by  heat  is  temporarily 
dissolved  in  the  air  and  is  said  to  be  sublimed. 

Aqua  destillata  (U.  S.  P.)  is  prepared  by  distilling  1000  parts 
of  water,  throwing  away  the  first  condensation  of  100  parts  as 
likely  to  contain  dissolved  gases  such  as  ammonia;  saving  the 
next  800  parts,  and  leaving  the  last  100  parts  in  the  retort  lest 
the  thickened  fluid  in  boiling  should  spray  over  its  salts. 

Atmospheric  Water. — Beside  the  visible  forms  of  cloud  or 
fog,  the  moisture  of  the  air  exists  as  an  invisible  vapor.  The 
actual  presence  and  amount  of  this  water  may  be  shown  by  sending 
the  measured  air  through  a  drying  tube  containing  calcium  chlorid; 
the  salt  grows  moist  and  increases  in  weight.  A  given  volume 
of  air  is  found  to  hold  amounts  of  water  vapor  varying  with  the 
pressure  and  temperature.  While  some  moisture  is  always  pres- 
ent, it  rarely  happens  that  the  air  is  saturated,  commonly  the 


86 


NON-METALS 


moisture  present  reaching  only  from  50  to   70  per  cent,  of  the 
maximum. 

By  cooling  the  air  sufficiently  a  temperature  is  reached  at 
which  the  aqueous  vapor  has  the  pressure  of  its  saturation-point. 
The  slightest  decline  now  causes  the  vapor  to  condense  as  dew. 
This  temperature  is  known  as  the  dew-point.  A  hygrometer  is 
an  instrument  constructed  to  determine  the 
amount  of  moisture  in  the  air.  The  one  com- 
monly used  consists  of  two  thermometers,  one 
dry,  while  around  the  bulb  of  the  other  is 
wrapped  a  cotton  wick  kept  wet  by  one  end 
dipping  in  a  vessel  of  water.  The  wet  bulb, 
by  evaporation,  indicates  a  lower  temperature 
than  the  dry-bulb  instrument.  The  rate  of 
evaporation  is  the  cause  of  the  difference,  and 
this  depends  on  the  amount  of  moist  vapor  and 
the  temperature.  If  the  difference  between  the 
instruments  be  great  the  air  is  dry,  if  slight  the 
air  is  moist.  By  means  of  tables  these  fac- 
tors can  be  converted  into  relative  humidity. 

Relative  humidity  is  a  term  applied  to  this 
fraction  of  full  saturation  for  the  air  at  existing 
temperature  and  pressure.  Relative  humidity 
of  100  means  that  the  air  is  saturated,  and 
that  water  will  be  precipitated  should  the  temperature  or  pressure 
decline.  An  increase  of  temperature  or  pressure  would  raise  the 
capacity  of  the  air  as  a  solvent,  and  the  relative  humidity  would 
fall.  Less  than  50  per  cent,  makes  the  air  dry;  with  more  than 
70  per  cent,  it  is  humid  and  depressing  to  the  vital  powers. 


FIG.  32. — Wet-  and  dry- 
bulb  hygrometer. 


HYDROGEN  DIOXID   OR    PEROXID 

Formula,  H2O2.     Molecular  weight,  34.     Specific  gravity,  1.455. 

A  trace  of  hydrogen  dioxid  is  found  in  saliva,  in  the  air,  in  snow, 
and  in  rain-water. 

Preparation. — Dilute  mineral  acids  acting  on  barium  dioxid 
will  produce  hydrogen  peroxid  mixed  with  water. 

BaO2       +        H2SO4  BaSO4        +        H2O2 

Barium  dioxid.  Sulphuric  acid.  Barium  sulphate.  Hydrogen  dioxid. 

Sodium  perborate  is  decomposed  by  water  yielding  sodium 
metaborate  and  hydrogen  dioxid  in  solution. 


NaBO3 

Sodium  perborate. 


H2O       — >       NaBO2 

Sodium  metaborate. 


H909. 


HYDROGEN    DIOXID    OR    PEROXID  87 

In  a  concentrated  form  for  use  as  a  bleaching  agent  it  is 
obtained  by  the  action  of  dilute  acids  on  sodium  peroxid. 

Na2O2       +        2HC1  2NaCl        +        H2O2. 

Sodium  peroxid.          Hydrochloric  acid.  Sodium  chlorid. 

Water  becomes  a  source  in  dissolving  sodium  peroxid. 
2H2O       +       Na2O2       =       2NaHO       +       H2O2. 

Properties. — When  pure  hydrogen  peroxid  is  a  syrupy  liquid 
without  color  or  odor,  but  with  a  metallic  taste,  and  having  a  ting- 
ling effect  on  the  mouth.  It  is  soluble  in  water,  alcohol,  and 
ether  in  all  proportions.  The  pure  form  decomposes  readily  into 
water  and  oxygen  at  ordinary  temperatures,  more  rapidly  at 
higher  temperatures.  Practically  it  is  oxidized  water. 

H2O2       7Z>       H2O       +       O       +       23,100  cal.  (96  kj). 

It  may  give  off  475  volumes  of  oxygen,  while  the  ordinary 
dilute  form  yields  about  10  volumes.  When  diluted  and  slightly 
acidulated  it  is  much  more  stable  and  may  be  concentrated  to  an 
extreme  degree  by  careful  evaporation  under  60°  C.  (140°  F.) 
without  decomposition. 

Catalytic  Reactions. — When  concentrated  hydrogen  dioxid 
comes  in  contact  with  certain  metals,  as  platinum  or  certain  oxids, 
as  manganese  dioxid,  it  breaks  up  explosively  into  water  and 
oxygen.  A  piece  of  spongy  platinum,  when  immersed  in  dilute 
hydrogen  dioxid,  becomes  enveloped  in  a  layer  of  oxygen  gas. 
Removing  this  layer  of  oxygen  another  layer  forms,  and  so  on, 
until  the  dioxid  is  to  a  great  degree  decomposed,  the  platinum 
remaining  unaffected. 

Catalysis  is  chemical  action  as  affected  by  the  presence  of  a 
substance  which  does  not  itself  enter  into  the  reaction.  A  cat- 
alyzer is  a  body  which,  without  appearing  as  an  end-product  in 
a  chemical  reaction,  alters  its  velocity.  While  in  most  cases  the 
catalyzer  hastens  the  change,  ''positive  catalyzers"  some  bodies,  like 
hydrocyanic  acid,  inhibit  action,  and  hence  may  be  called  ''retard- 
ing catalyzers."  The  agent  usually  appears  to  act  much  as  a  lub- 
ricant does  on  machinery — that  is,  it  accelerates  a  movement  which 
would  otherwise  occur  much  more  slowly  if  at  all,  the  lubricant 
itself  not  being  consumed  in  the  process. 

The  Energy  of  Hydrogen  Dioxid. — To  decompose  water, 
H2O  (a  stable  substance),  it  requires  a  strong  electric  current  or 
very  high  temperature.  Hydrogen  dioxid,  H2O2,  with  its  addi- 
tional atom  of  oxygen,  acquires  instability  in  a  high  degree.  In 


88  NON-METALS 

giving  up  that  oxygen  a  large  amount  of  heat  is  liberated.  Each 
molecule  of  the  dioxid  holds  that  much  more  intrinsic  energy  than 
the  molecule  of  water  to  which  it  is  converted.  This  intrinsic 
energy  gives  it  high  instability  and  chemical  activity  in  proportion. 

Aqua  hydrogenii  dioxidi,  U.  S.  P.  (oxygenated  water),  is  a  solu- 
tion in  water  of  about  3  per  cent,  by  weight  of  the  dioxid  correspond- 
ing to  about  10  volumes  of  available  oxygen.  Without  color  or 
odor,  it  has  a  peculiar,  feebly  sour  taste,  denoting  its  character  as 
acid.  Mixed  with  saliva  it  evolves  oxgyen,  as  it  also  does  when 
mixed  with  pus. 

To  prevent  spontaneous  deterioration  and  explosive  expulsion 
of  the  stopper  it  is  best  kept  uncorked  in  a  refrigerator.  By  means 
of  glycerin  a  more  stable  solution  is  prepared.  A  solution  in  ether 
is  called  ozonic  ether. 

Uses  in  the  Arts. — As  an  oxidizing  agent  it  has  quite  remark- 
able bleaching  powers,  which  are  employed  in  bleaching  hair, 
ostrich  feathers,  and  wool.  Books  and  engravings  stained  by 
mould  and  time  are  safely  cleaned  by  it. 

Uses  in  Medicine. — It  is  an  antiseptic,  destroying  bacteria; 
a  deodorant,  decomposing  hydrogen  sulphid;  and  a  styptic,  coagu- 
lating the  blood.  It  is  of  great  service  as  a  topic  application  to 
the  throat  in  scarlatina  and  diphtheria,  or  as  a  disinfectant  lotion 
for  abscesses  and  wounds.  When  internally  administered  in  doses 
of  f3j-iv,  well  diluted,  care  should  be  taken  that  the  solution  be 
free  from  barium  and  hydrofluoric  acid.  The  small  amount  of 
free  acid,  if  present,  may  be  neutralized  with  a  sufficient  amount 
of  sodium  bicarbonate.  It  is  given  by  the  mouth  as  an  antidote 
to  the  cyanids,  phosphorus,  and  the  alkaloids.1 

With  hydrocyanic  acid  it  forms  oxamid;  hence,  if  potassium 
cyanid  has  been  taken,  a  tablespoonful  of  vinegar  must  be  added 
to  liberate  the  acid  from  the  cyanid. 

2HCN         +         H202  C202N2H4 

Hydrocyanic  acid.  Oxamid. 

Not  only  is  the  stomach  flushed  with  the  dioxid  diluted,  but 
15  m.  of  the  official  preparation  are  also  injected  subcutaneously 
every  ten  minutes  until  respiration  improves. 

Incompatibles. — To  arsenic  and  the  sulphids,  hydrogen 
peroxid  supplies  oxygen,  but  it  reduces  many  compounds,  like 

1  Solutions  of  potassium  permanganate  and  hydrogen  dioxid  when  mixed,  recip- 
rocally promote  their  yield  of  oxygen.  The  official  3  per  cent.  H2O2,  about  35  cc. 
diluted  with  a  liter  of  water,  when  mixed  with  a  solution  of  potassium  permanganate, 
2  gm.  in  5  cc.  of  diluted  acetic  acid  to  a  liter  of  water,  produces  at  once  energetic 
disengagement  of  oxygen.  They  should  be  kept  separate  until  needed  and  brought 
into  contact  only  at  the  site  of  the  disease;  as  antidotes,  the  above  dioxid  solution 
should  be  given  in  doses  of  a  tablespoonful  first  and  followed  each  time  by  an 
equal  amount  of  the  permanganate. 


SOLUTION  89 

manganese  dioxid,  silver  oxid,  and  potassium  iodid.  Many  sub- 
stances in  a  state  of  fine  division,  acting  by  catalysis,  cause  hydrogen 
dioxid  to  lose  its  oxygen.  Among  such  substances  are  included 
all  the  ferments  or  enzymes,  ordinary  dust,  powdered  charcoal, 
fibrin,  platinum,  and  gold.  Hydrogen  dioxid  is  also  decomposed 
by  albumin,  ammonia,  iodids,  chlorids,  bromids,  chlorin-water, 
solution  of  chlorinated  soda,  carbolic  acid,  ferric  salts,  hydrocyanic 
acid,  lime-water,  the  permanganates,  and  alcoholic  tinctures. 

Tests. — (i)  Starch  and  Iodids. — A  few  drops  of  a  solution  of 
potassium  or  cadmium  iodid  are  added  to  a  cold  solution  of  starch 
acidulated  with  acetic  or  citric  acid.  Then  the  fluid  to  be  tested 
is  added.  Hydrogen  dioxid,  even  in  the  presence  of  ferrous 
sulphate,  produces  a  blue  color,  liberating  free  iodin,  which  unites 
with  the  starch.  Other  oxidizing  agents  liberate  iodin,  but  not 
in  the  presence  of  ferrous  sulphate. 

2KI         +         H2O2  2KOH         +         I2. 

This  test  will  show  hydrogen  dioxid  when  there  is  present 
only  0.05  mgm.  per  liter. 

(2)  Perchromic  Acid. — When  acidulated  with  dilute  sulphuric 
acid,  hydrogen  dioxid  will  cause  potassium  dichromate  to  form 
blue  perchromic  acid — 4CrO3.  By  shaking  with  ether  and  setting 
aside,  the  product  separates  as  a  supernatant  transient  violet- 
blue  layer.  No  other  substance  oxidizes  chromic  to  perchromic 
acid. 


SOLUTION.    DIFFUSION.    DIALYSIS.    OSMOSIS 

SOLUTION 

SOME  solids  when  immersed  in  water  disappear  in  it,  imparting 
to  the  liquid  their  own  properties,  such  as  color,  odor,  and  taste. 
They  assume  for  the  time  being  the  liquid  state.  A  solution  of 
sugar  is  sweet,  and  of  salt  brackish,  the  chemical  behavior  being 
that  of  the  original  solid.  The  particles  of  the  solute  are  diffused 
so  evenly  in  the  solvent  that  every  part  of  the  liquid  contains  equal 
amounts  dissolved  in  it.  One  grain  of  fluorescin  or  uranin  will 
render  fluorescent  or  will  color  one  hundred  million  grains  of 
water.  The  original  grain  has  been  divided  infinitely  in  the 
process  of  absorption  by  water. 

Solutions  are  homogeneous  mixtures  of  two  or  more  elements 
or  compounds  which  cannot  be  separated  mechanically. 


9° 


NON-METALS 


Solutions  of  Solids  in  Liquids.— It  is  a  general  rule  that 
some  portion  of  a  solid,  albeit  infinitesimal,  always  dissolves  in 
a  liquid  in  contact  with  it.  A  trace  of  platinum  dissolves  in  water. 
This  is  not  the  only  form  of  solution,  but,  being  the  most  familiar, 
the  word  solution  is  taken  to  mean  the  solution  of  a  solid  in  a  liquid. 
As  though  it  were  a  chemical  effect,  there  is  a  limit  to  the  amount 
of  any  solid  dissolvable  in  a  certain  amount  of  any  liquid.  This 
limit  depends  upon  the  nature  of  the  solvent,  the  nature  of  the 
solute,  and  the  temperature. 

As  more  substances  are  freely  soluble  in  water  than  in  any  other 
liquid,  we  speak  of  the  solubility  of  a  substance  without  naming 
the  solvent,  meaning  water.  Water,  however,  is  not  a  good 
solvent  for  a  large  number  of  solids — like  the  resins,  which  dissolve 
freely  in  alcohol;  phosphorus,  soluble  in  ether;  sulphur,  soluble 
in  carbon  bisulphid;  and  gutta-percha,  soluble  in  chloroform. 
While  theoretically  all  solids  are  said  to  be  soluble  in  water,  to 
some  degree  discoverable  by  physical  tests,  the  amount  of  gold  and 
other  metals,  quartz  and  many  other  minerals,  is  so  small  as  not 
to  be  discovered  by  chemical  tests.  These  substances  are  con- 
sidered to  be  practically  insoluble,  while  the  contrary  is  the  case 
with  many  metallic  salts,  acids,  alkalies,  sugars,  and  a  host  of 
organic  products.  The  solubility  of  some  of  these  is  very  great, 
yet  in  the  extremest  case  there  is  a  limit  beyond  which  it  is  not 
possible  to  dissolve  a  solid  in  a  liquid.  This  limit,  constant  at 
any  given  temperature,  is  the  point  of  saturation.  The  solution 
is  said  to  be  saturated.  In  making  a  saturated  solution  it  will  be 
found  a  great  help  to  have  the  solid  pulverized  and  stirred  or 
shaken  with  the  solvent.  Practically  this  method  is  not  so  rapid 
as  one  based  upon  the  fact  that  solubility  of  most  substances 
rises  with  the  temperature.  Thus,  at  o°  C.  (32°  F.),  100  parts 
of  water  dissolve  26  parts  of  magnesium  sulphate;  at  40°  C. 
(104°  F.),  45  parts;  at  100°  C.  (212°  F.),  74  parts.  The  con- 
centration of  a  solution  means  the  amount  of  the  solute  in  a  given 
quantity  of  the  solvent. 

After  having  made  a  saturated  solution  of  a  calcium  salt  at 
ordinary  temperatures,  if  heat  be  applied,  the  effect  is  the  pre- 
cipitation of  the  salt.  Common  salt  is  almost  equally  soluble  at 
all  temperatures.  With  the  great  majority  of  solids,  such  as  sugar 
and  alum,  if  hot  water  be  used  to  make  the  solution  and  a  large 
quantity  of  the  solid  be  shaken  with  it,  when  the  solution  cools  the 
excess  dissolved  at  the  higher  temperature  will  be  thrown  out  and 
a  saturated  solution  be  left.  Sometimes  the  clear  liquid  may  be 
cooled  without  throwing  out  all  excess.  Thus  we  may  get  a 
•solution  which  at  any  given  temperature  holds  more  of  the  solute 
than  a  simple  saturated  solution.  The  equilibrium  is  not  stable 


SOLUTION  91 

because  agitation  with  a  crystal  of  the  undissolved  substance 
will  cause  the  excess  of  the  solid  in  solution  to  be  deposited. 
The  supersaturated  solution  is  thus  converted  into  a  saturated 
one. 

If  sodium  sulphate  be  dissolved  by  aid  of  heat  and  the  clear 
liquid  free  from  undissolved  particles  be  allowed  to  cool  quietly, 
excluding  dust,  a  crystal  of  the  same  salt  dropped  into  the  super- 
saturated solution  causes  immediate  crystallization  with  elevation 
of  temperature. 

While  the  dissolved  substance  can  not  be  separated  by  mechan- 
ical means,  it  may  by  evaporation  of  the  liquid.  The  solute  is  not 
carried  over  in  the  vapors,  but  is  recovered  unchanged. 

Solutions  of  Gases  in  Liquids. — All  liquids  possess  the 
power  (though  it  may  be  infinitely  small)  of  absorbing  all  gases. 
The  amount  absorbed  varies  with  the  nature  of  the  liquid,  the 
nature  of  the  gas,  the  temperature  of  the  solvent,  and  the  pressure 
on  the  gas.  At  o°C.  (32°  F.)  a  liter  of  water  dissolves  only  half 
as  much  carbon  dioxid  as  an  equal  volume  of  alcohol. 

It  has  been  previously  stated  that  oxygen,  hydrogen,  nitrogen, 
and  air  are  soluble  in  water  to  a  slight  extent  only.  We  shall 
learn  that  chlorin  and  hydrogen  sulphid  are  more  soluble,  while 
hydrochloric  acid  and  ammonia  are  absorbed  by  water  in  large 
amounts. 

The  extent  of  solubility  is  much  influenced  by  temperature 
and  pressure.  As  the  temperature  rises  the  amount  of  gas  dis- 
solved decreases.  At  10°  C.  (50°  F.)  100  volumes  of  water  will 
hold  in  solution  no  volumes  of  nitrous  oxid;  when  heated  to 
20°  C.  (68°  F.)  much  gas  escapes,  leaving  only  67  volumes. 

The  relation  of  pressure  to  solubility  is  expressed  in  Henry's 
law:  The  amount  oj  a  gas  absorbed  by  a  liquid  is  directly  propor- 
tional to  the  pressure  to  which  the  gas  is  subjected.  Thus,  under 
a  pressure  of  five  atmospheres,  water  dissolves  five  times  as  much 
carbon  dioxid  as  under  a  pressure  of  one  atmosphere. 

Solutions  of  Liquids  in  Liquids.— These  belong  to  one  of 
two  classes:  first,  where  the  liquids  mix  in  all  proportions  homo- 
geneously, as  alcohol  and  water;  second,  where  they  dissolve  in 
each  other  to  a  limited  extent  only,  as  ether  and  water.  Theoret- 
ically, all  liquids  are  soluble  in  each  other  to  at  least  an  infini- 
tesimal degree,  but,  practically,  there  are  liquids  which  are  not 
miscible,  such  as  oil  and  water. 

When  liquids  are  freely  miscible,  the  mixture  often  has 
properties  representing  the  sum  of  those  of  the  components,  though 
they  are  never  strictly  additive.  In  most  cases  there  is  a  change 
of  volume;  usually  the  mixture  shrinks,  but  sometimes  it  increases. 
In  most  cases  there  is  a  change  of  temperature  which  may  be 


92  NON-METALS 

either  a  rise  or  a  fall.     When  alcohol  is  mixed  with  water  a  con- 
traction of  volume  occurs  and  the  temperature  of  the  mixture  rises. 

When  liquids  are  miscible  to  a  limited  extent  only,  the 
properties  of  the  mixture  can  not  be  assumed  to  be  the  sum  of  the 
constituents.  When  there  is  an  excess  of  one  liquid  and  a  mechan- 
ical separation,  it  will  be  found  that  each  separate  liquid  has 
dissolved  a  different  amount  of  the  other.  If  equal  volumes  of 
ether  and  water  be  shaken  together  and  set  aside,  they  will  soon 
form  two  layers.  The  upper  layer  of  ether  contains  2  per  cent,  of 
dissolved  water;  the  lower  layer  consists  of  water  holding  10  per 
cent,  of  the  ether  dissolved  in  it.  It  can  be  stated  that  the  mutual 
solubility  is  limited  only  at  ordinary  temperatures.  By  heating, 
the  liquids  will  at  last  reach  a  point  where  they  become  miscible 
in  all  proportions. 

Solutions  of  Gases  in  Gases. — When  two  gases  in  contact 
do  not  unite  chemically,  they  diffuse  into  one  another,  making 
a  uniform  mixture,  as  the  nitrogen  and  oxygen  of  the  air.  There 
is  no  limit  to  the  capacity  of  a  gas  to  dissolve  another,  the  result- 
ing mixture  having  the  combined  properties  of  the  components. 
The  pressure  of  the  mixture  equals  the  sum  of  the  pressures  of 
the  constituents  (see  p.  41). 

Solutions  of  Liquids  in  Gases.— Generally  speaking,  liquids 
will  evaporate  into  surrounding  gases.  The  gas  dissolves  the 
liquid  with  such  freedom  that  the  vapor-pressure  of  the  evap- 
orated liquid  is  the  same  as  it  would  be  in  a  vacuum  (see  p.  39). 

Solutions  of  Solids  in  Gases. — Certain  solids,  such  as  iodin, 
without  being  first  liquefied,  pass  into  the  state  of  vapor  and  dis- 
solve in  the  air  or  other  gases.  The  solubility  increases  with  rise 
of  temperature. 

DIFFUSION 

Diffusion  of  Gases.— In  the  section  that  treats  of  hydrogen 
(page  81)  it  was  shown  that  a  gas  passes  through  the  porous  walls 
of  a  cell  much  faster  than  the  air  passes  out.  If  the  experiment 
be  repeated  with  air  outside  and  carbon  dioxid  inside,  a  similar 
effect  is  produced,  the  lighter  gas  diffusing  more  rapidly  than  the 
heavier. 

Graham's  law  states  that  the  velocities  of  diffusion  of  any  two 
gases  are  inversely  as  the  square  roots  of  their  densities.  Oxygen 
weighing  16  diffuses  one-fourth  as  fast  as  hydrogen  weighing  i; 
chlorin  weighing  36  diffuses  at  one-sixth  the  rate  of  hydrogen. 
This  follows  from  the  kinetic  theory  of  gases,  which  assumes  that 
the  mean  velocities  of  the  molecules  of  gases  are  inversely  propor- 
tional to  the  square  roots  of  their  densities. 

Diffusion  of  Liquids.— If  a  cylindric  vessel  be  partly  filled 
with  water  and  the  water  underlaid  with  a  colored  solution  (a  sat- 


DIALYSIS  93 

urated  solution  of  copper  sulphate),  by  pouring  the  latter  solution 
through  a  long  funnel  reaching  to  the  bottom  of  the  vessel  two 
well-defined  layers  will  be  formed.  If  the  cylinder  be  set  aside 
for  a  few  days  it  will  be  seen  that  the  blue  color  has  risen  gradually 
and  extended  into  very  part  of  the  water,  making  a  uniform 
tint  throughout.  Chemical  analysis  will  prove  that  the  copper 
salt  has  distributed  itself  equally  throughout  the  solvent,  making 
a  homogeneous  solution.  Likewise  two  solutions  of  different  sub- 
stances will  diffuse  into  each  other  until  there  is  but  one  homo- 
geneous mass.  Moreover,  regardless  of  the  weight  of  the  dissolved 
substance,  the  solution  maintains  this  property  of  uniform  distri- 
bution indefinitely.  The  force  of  diffusion  overcomes  the  counter- 
acting force  of  gravity. 

From  an  extended  series  of  experiments  Graham  deduced  the 
following  conclusions:  The  quantities  of  a  dissolved  salt  which 
diffuse  in  equal  times  are  proportional  to  the  concentration  of  the 
solution,  and  to  the  rise  in  temperature. 

Different  substances  have  different  rates  of  diffusion,  cane- 
sugar  diffusing  with  seven  times  the  velocity  of  albumin.  Iso- 
morphous  salts  frequently  show  equal  rapidity.  A  double  salt, 
such  as  alum,  may  be  resolved  into  its  components  by  means  of 
their  unequal  velocity,  the  more  diffusible  part  moving  away  at 
a  greater  rate. 

DIALYSIS 

If  a  drum  of  glass  open  at  both  ends  be  closed  at  one  end  with 
a  stretched  membrane,  such  as  bladder  or  parchment,  then  floated 
on  water,  and  a  mixture  of  substances,  such  as  sugar  and  albumin, 
placed  in  it,  a  remarkable  separation  of 
the  sugar  and  albumin  occurs.  The  sugar 
passes  out  through  the  membrane,  while 
the  albumin  remains  behind. 

This  process  of  separation  is  known  as 
dialysis,  the  instrument  is  a  dialyzer.  The 
sugar  is  the  diffusate,  the  albumin,  the  dial- 
ysate.  Graham  divided  all  substances  into 
two  classes:  crystalloids,  those  which  dif- 
fuse  and  are  also  crystallizable;  colloids, 

those  which  are  unable  to  pass  through  the  membrane  and  which 
are  also  amorphous,  like  gum  or  glue.  To  the  class  of  crystal- 
loids belong  sugar,  the  mineral  salts,  and  acids;  to  the  colloids 
belong  albumin,  gelatin,  starch,  and  gum.  Crystalloids  have 
molecules  sufficiently  small  to  pass  where  the  larger  molecules 
of  the  colloid  can  not  readily  move.  In  some  cases  relatively 
small  molecules  appear  to  cling  together  to  form  solution  aggre- 
gates which  can  not  diffuse.  Some  of  the  metals — platinum,  gold, 


94 


NON-METALS 


and  silver — can  be  obtained  in  a  condition  known  as  colloid  solu- 
tion. A  strong  electric  current  is  sent  through  water  by  platinum 
electrodes  with  tips  close  enough  to  make  an  electric  arc.  Minute 
particles  of  platinum  are  torn  off  in  aggregates,  making  a  brown 
solution  which  does  not  dialyze,  and  hence  is  called  colloidal. 
Viewed  by  the  ultramicroscope,  the  "  solution"  proves  to  be  a  sus- 
pension of  shining  metallic  particles.  Such  a  solution  has  the 
catalytic  power  of  a  ferment  on  sugar  and  fat  (p.  536). 


OSMOSIS 

If  a  dialyzer  full  of  molasses  or  brine  be  immersed  in  water  it  will 
be  noticed  that  the  contents  of  the  inner  vessel  increase  and  the  mem- 
brane appears  to  be  forced  up.  If  instead  of  a  cylindric  drum  a 
long-stem  funnel  be  used  (Fig.  34),  stretching  the  parchment  over 

the  head  of  the  funnel,  b-a,  we 
have  an  osmometer,  or  apparatus 
for  observing  the  phenomenon 
of  the  transmission  of  liquids,, 
which  causes  the  level  of 
the  fluid  to  rise  as  in  tube 
n.  We  have  seen  that  the  pas- 
sage of  a  dissolved  substance 
is  called  dialysis;  when  the 
passing  molecules  are  those 
of  the  solvent  it  is  termed  os- 
mosis. There  is  in  reality  an 
interchange,  but  more  mole- 
cules of  water  stream  into  the 
brine  than  of  salt  out  to  the 
water. 

A  better  medium  for  show- 
ing this  pressure  of  the  water 
toward  a  solution  of  salts  is 
the  semipermeable  membrane 
oj  Pfefter,  made  by  precipita- 
ting gelatinous  copper  ferro- 
cyanid  within  the  pores  of 
a  membrane  or  the  walls  of 
a  porous  cell.  This  is  per- 
meable to  the  water,  but  not 
to  the  dissolved  substance;  it 
is  not  a  dialyzer.  When  a 
solution  of  cane-sugar  is  put  inside  of  an  osmometer  with  this  arti- 
ficial membrane  separating  it  from  water,  the  osmotic  current  is 


FIG.  34. — Endosmometer:  a-b,  porous  membrane; 
v,  diffusate  risen  to  n. 


OSMOSIS  95 

toward  the  sugar,  v,  no  sugar  passing  out.  In  their  futile  efforts 
to  push  on  out  toward  the  water  the  sugar  molecules  exert  a  pres- 
sure which  is  toward  all  the  boundaries  of  the  cell,  including  the 
free  surface  of  liquid  in  the  tube  n.  The  free  surface  of  any  liquid 
behaves  like  a  thin  film  or  movable  partition. 

It  moves  upward,  enlarging  the  volume  of  fluid  in  the  cell,  making 
easier  the  entrance  of  water  through  the  membrane.  This  movement 
causes  the  level  of  water  in  the  stem  to  rise  to  a  certain  point,  when 
the  pressure  reaches  an  equilibrium  with  the  weight  of  the  column 
of  fluid.  This  highest  degree  of  pressure  is  known  as  the  osmotic 
pressure  of  the  solution.  If  the  semipermeable  cell  be  filled  with 
a  normal  solution  of  cane-sugar,  and  the  stem  be  a  capillary  tube, 
pure  water  will  press  in  so  fast  that  the  liquid  in  the  tube  rises  more 
than  a  foot  an  hour,  and  in  a  day  will  reach  a  pressure  of  thirty  feet 
of  sugar  solution.  By  connecting  to  the  cell  a  tube  of  the  form 
used  for  manometers,  we  can  calculate  the  pressure  in  exact  terms. 

Osmotic  pressure  is  that  push  of  the  molecules  of  a  solute  upon  its 
solvent  which  causes  a  flow  through  a  membrane  into  the  solution. 
Its  laws  are: 

(1)  At  a  constant  temperature  the  osmotic  pressure  is  propor- 
tional to  the  concentration  of  the  solution. 

(2)  With  a  given  solution  it  is  proportional  to  the  absolute  tem- 
perature. 

(3)  Under  constant  conditions  of  concentration  and  tempera- 
ture different  substances  in  solution  exert  different  pressures. 

(4)  The  molecular  weights  in  grams  per  liter  of  different  sub- 
stances exert  the  same  pressure  at  the  same  temperature. 

These  laws  resemble  closely  those  stated  as  governing  the 
pressure  of  gases  in  confined  spaces  (see  p.  40).  The  osmotic 
pressure,  like  the  gas  pressure,  varies  with  the  concentration,  and 
increases  -^rs  f°r  every  rise  of  i°  C.,  or  ^-§-5-  for  every  i°  F. 

According  to  the  law  oj  Avogadro,  equal  volumes  of  all  gases 
at  the  same  temperature  and  pressure  contain  the  same  number 
of  molecules.  So  in  equal  volumes  of  solutions  having  the  same 
osmotic  pressure  there  are  the  same  number  of  molecules.  The 
osmotic  pressure  of  a  solution  of  cane-sugar  is  exactly  equal  to 
the  gas  pressure  of  a  gas  with  the  same  number  of  molecules  in 
a  given  volume.  The  gas  pressure  exerted  by  a  gas  molecule 
equals  the  osmotic  pressure  of  a  dissolved  molecule.  These  laws 
do  not  apply  to  the  osmotic  pressures  of  most  salts,  all  the  strong 
acids,  and  all  the  strong  bases,  which  are  always  greater  than  the 
laws  would  lead  us  to  expect. 

To  solve  the  problem  presented  by  so  many  exceptions,  the 
theory  of  ionization  or  electrolytic  dissociation  is  needed.  If  the 
acids,  bases,  and  salts  exert  abnormal  osmotic  pressure  they  must 


96  NON-METALS 

have  more  dissolved  particles  than  can  be  accounted  for  by  their 
molecules.  Let  us  suppose  that  the  theory  given  (p.  52)  to  explain 
electrolysis  be  true — that  is,  that  in  making  solutions  of  salts,  acids, 
and  bases  there  is  a  partial  breaking  up  of  the  molecules,  not  into 
free  atoms,  but  into  electrically  charged  parts  called  ions,  which 
may  be  charged  atoms  or  charged  groups.  In  this  way  we  can 
conceive  of  more  particles  than  are  accounted  for  by  the  molecules. 
According  to  the  method  of  Arrhenius  the  percentage  of  molecules 
broken  down  into  ions  can  be  calculated.  When  this  is  done, 
there  is  found  the  right  proportion  of  particles,  i.  e.,  molecules  plus 
ions,  to  bring  the  exceptional  substances  under  the  reign  of  the 
laws  above  stated. 

Osmotic  pressure  being  the  push  of  the  particles  of  a  solute, 
it  tends,  in  proportion  to  their  number,  to  impede  that  free  move- 
ment of  the  molecules  of  the  solvent  which  is  necessary  to  arrange 
them  anew  for  the  frozen  state.  For  instance,  solutions  of  equal 
osmotic  pressure  have  also  the  same  freezing-point.  Freezing-point 
depression  in  a  solution  is  proportional  to  the  number  of  particles 
dissolved.  The  amount  of  freezing-point  lowering  of  any  normal 
(gram-molecular)  solution  in  water  has  been  stated  to  be  the  constant 
1.87  (p.  38). 

Therefore,  the  osmotic  pressure  of  a  solution  can  be  calculated 
by  dividing  1.87  into  the  amount  of  lowering  of  the  freezing-point 
of  that  solution  in  Centigrade  degrees  (its  A — delta).  Blood- 
serum  freezes  0.56°  C.  below  the  freezing-point  of  pure  water. 
0.56°  C.  divided  by  1.87  gives  0.3.  Now  the  constant  osmotic 
pressure  for  normal  solutions  of  undissociated  substances  is  22 
atmospheres;  therefore,  22  multiplied  by  0.3  gives  6.6  atmospheres 
as  the  osmotic  pressure  of  blood-serum.  A  solution  of  a  salt 
having  the  same  osmotic  pressure  as  blood-serum  is  said  to  be 
isotonic  or  isosmotic,  such  as  0.95  per  cent,  sodium  chlorid.  A 
solution  of  higher  pressure  is  said  to  be  hypertonic;  one  of  lower, 
hypotonic. 

The  physiologic  solution  of  common  salt  is  made  a  little  less 
than  this  strength,  7  to  9  grams  per  liter  (132  gr.  to  i  quart),  so 
that  when  injected  by  hypodermoclysis  it  will  diffuse  as  freely  as 
blood-serum  itself.  The  laws  of  osmotic  pressure  have  been 
a  great  help  to  physiologists  in  solving  the  problems  of  secretion 
and  absorption.  Cell  walls  are  semipermeable,  permitting  the  cells 
to  lose  or  gain  water  according  as  they  are  immersed  in  hypertonic 
or  hypotonic  fluids. 


NITROGEN  97 

NITROGEN  AND  THE  ARGON  GROUP 

NITROGEN   (Azote) 
Symbol,  N.     Atomic  weight,  14.04. 

Occurrence. — Free  nitrogen  constitutes  four-fifths  of  the  vol- 
ume of  the  air,  which  also  contains  a  trace  of  it  combined,  as 
ammonia  (NH3).  It  is  found  in  combination  in  nitrates  and 
many  animal  and  vegetable  substances. 

Preparation. — To  obtain  nitrogen  from  the  air,  the  oxygen 
must  be  removed.  A  piece  of  phosphorus  as  large  as  a  pea  is 
floated  on  a  cork  in  a  basin  of  water,  ignited,  and  covered  with 
a  bell-jar.  The  phosphorus  combines  with  the  oxygen,  forming 
clouds  of  phosphorus  pentoxid  which  are  absorbed  by  the  water. 
Left  in  the  jar  is  the  nitrogen,  containing  a  trace  of  CO2  and  of 
argon.  Nitrogen  can  be  obtained  more  pure  by  not  igniting  the 
phosphorus,  but  by  allowing  it  to  oxidize  slowly.  It  can  also  be 
prepared  by  heating  a  strong  solution  of  ammonium  nitrite  or  a 
mixture  of  ammonium  chlorid  and  potassium  nitrite. 

Properties. — Nitrogen  is  a  colorless,  tasteless,  inodorous  gas, 
with  a  specific  gravity  0.9701.  At  —130°  C.  (  —  202°  F.),  under 
280  atmospheres,  it  is  condensed  into  a  colorless  liquid.  It  will 
not  support  combustion,  nor  will  it  burn.  It  is  not  poisonous,  for 
if  so  the  air  would  kill.  All  animals  die  in  the  pure  gas,  owing 
to  the  absence  of  the  life-sustaining  oxygen. 

Because  it  does  not  combine  under  ordinary  circumstances  with 
any  common  substances  it  has  been  regarded  as  the  type  of  pas- 
sivity, but  this  can  be  said  more  properly  of  argon,  which  is  asso- 
ciated with  the  nitrogen  in  the  air.  The  nitrogen  of  the  air  is 
made  available  for  use  through  union  with  its  associate  oxygen 
only  by  the  expenditure  of  much  energy,  which  is  stored  up  for 
later  work  on  the  decomposition  of  the  resulting  compound. 
Flashes  of  lightning  in  nature  and  powerful  electric  discharges  in 
a  suitable  apparatus  compel  this  union.  The  living  energy  in 
the  nitrifying  bacteria  at  the  roots  of  pod-bearing  plants  causes 
a  combination  of  the  two  in  the  nitrates  of  the  soil,  which  give  it 
fertility.  For  the  growth  of  crops  dependence  is  largely  placed 
upon  animal  manures,  in  the  ammoniacal  components  of  which  is 
combined  nitrogen  oxidized  by  the  soil-bacteria  to  plant-food  ni- 
trates. Having  been  assimilated  by  the  plant,  the  combined 
nitrogen  is  taken  up  by  the  animal  in  the  proteins  of  food,  the 
nitrogen  circulating  through  both  in  various  forms,  but  always  in 
some  compound  essential  to  life.  Nitrogen  forms  compounds 
very  slowly,  and  most  of  them  decompose  with  great  readiness, 
some  of  them  explosively,  giving  back  the  energy  taken  up  in 
7 


98 


NON-METALS 


causing  their  union;  namely,  gunpowder,  nitroglycerin,  nitro- 
cellulose, or  gun-cotton.  Nitrogen  imparts  an  energetic  quality 
to  prussic  acid,  HCN;  to  nitric  acid,  HNO3;  to  ammonia,  NH3; 
to  powerful  alkaloids,  and  the  albuminous  principles.  These 
compounds  of  nitrogen  are  considered  in  other  places. 

Argon  and  Its  Congeners.— Until  recently  the  inert  con- 
stituent of  the  air  was  considered  to  be  nitrogen  only.  About  one 
part  of  the  80  per  cent,  of  so-called  nitrogen  in  the  air  has  been 
proved  to  consist  of  argon  and  its  congeners,  distinguished  by  the 
fact  that  they  show  no  evidence  of  chemical  attraction,  forming  no 
compounds,  and  hence  sometimes  called  the  "noble  gases." 

Argon  (A  =  40)  was  first  discovered  in  1894  by  removing  from 
a  measured  portion  of  air  first  its  oxygen,  by  means  of  phosphorus 
or  heated  copper,  and  then  its  nitrogen,  by  means  of  red-hot  mag- 
nesium, by  which  N  is  absorbed.  By  weight  it  forms  1.2  per  cent, 
of  the  air,  which  ratio  is  constant. 

Properties. — Argon  is  a  colorless,  odorless,  and  tasteless  gas 
having  a  vapor  density  19.941.  It  is  soluble  in  the  proportion 
of  4  parts  to  100  of  water,  and  it  solidifies  under  cold  and  pressure. 
It  has  a  peculiar  spectrum.  The  chemical  inactivity  makes  it 
a  difficult  matter  to  determine  its  combining  weight,  but  by  physical 
analogies  the  conclusion  has  been  reached  that  it  is  40. 

Helium  (He  =  4). —This  is  a  very  light  gas,  with  the  proper- 
ties of  argon.  It  was  first  suspected  to  be  an  unknown  element 
of  the  sun's  atmosphere,  causing  a  strong  line  in  the  yellow-green 
of  the  solar  spectrum.  The  same  line  has  been  found,  and  also 
those  due  to  argon  in  the  gases  evolved  on  ignition  of  certain 
minerals.  By  cooling  these  gases  to  extremely  low  temperatures 
they  are  condensed  to  a  liquid.  If  the  temperature  be  permitted 
to  rise,  the  helium  becomes  a  gas  first,  leaving  the  argon  a  liquid. 
In  air,  by  its  evaporation  from  the  liquid  state,  helium  and  three 
other  gases  with  characteristic  spectra  and  different  densities  have 
been  discovered  in  amounts  as  follows:  helium,  i  in  1,000,000; 
neon  (Ne  =  2o),  i  in  100,000;  krypton  (Kr  =  82),  i  in  1,000,000; 
and  xenon  (X=i28),  i  in  20,000,000. 


CARBON  AND   ITS  OXIDS 

CARBON 

Symbol,  C.     Atomic  weight,  12. 

Occurrence. — Free  carbon  exists  in  nature  in  three  allotropic 
forms:  as  uncrystalline  or  amorphous  carbon;  graphite,  either 
amorphous  or  imperfectly  crystalline;  and  as  diamond,  in  octa- 


CARBON  99 

hedral  crystals.  In  the  air  it  exists  in  combination  as  carbon 
dioxid.  It  occurs  widely  distributed  in  the  mineral  kingdom  in 
carbonates,  and  it  is  a  constituent  of  all  organic  substances,  being 
more  necessary  to  the  vital  processes  than  any  other  element. 

Properties. — All  forms  of  carbon  have  the  following  proper- 
ties in  common:  They  are  solid,  tasteless,  odorless,  and  except  at 
very  high  temperatures,  insoluble,  infusible,  and  non-volatile. 

Diamond  is  almost  pure  carbon;  usually  being  transparent 
and  colorless,  though  colored  specimens  are  not  rare.  Particles 
of  carbon  in  molten  iron  change  to  small  crystals  of  diamond  by 
the  heat  and  the  pressure  of  the  metal  as  it  contracts  on  cooling.  It 
is  cut  into  many  facets  at  certain  angles,  so  as  to  enhance  the  luster 
due  to  its  high  dispersive  and  refractive  power.  As  the  hardest 
substance  known,  it  is  cut  only  by  its  own  dust.  It  has  a  specific 
gravity  3.55.  It  is  a  non-conductor  of  electricity  and  a  poor  con- 
ductor of  heat.  Resisting  all  lower  temperatures,  under  the  heat 
of  the  electric  arc,  in  a  vacuum,  it  is  converted  into  graphite;  in 
the  air  it  burns  to  carbon  dioxid. 

Graphite  or  plumbago  is  a  bluish-black,  friable  substance 
with  a  metallic  luster,  but  having  a  greasy  feeling  and  leaving 
a  line  when  drawn  across  paper,  hence  called  black  lead.  It  is 
the  "lead"  in  the  common  lead-pencil.  Its  specific  gravity  is  2.18; 
its  crystals  are  six-sided  plates.  The  charcoal  filaments  of  the 
Edison  electric  lamp  in  time  change  by  heat  to  graphite.  A  good 
conductor  of  heat  and  electricity,  it  burns  at  a  high  heat  to  carbon 
dioxid. 

Amorphous  Carbon. — The  purest  is  lamp-black,  the  soot 
of  burning  resins  or  oils.  Other  forms  less  pure  are  wood  char- 
coal, animal  charcoal,  mineral  coal,  and  coke.  All  of  these  are 
endowed  with  great  energy,  convertible  into  heat,  light,  electricity, 
or  mechanical  motion.  When  burned  in  air  the  end-product  is  car- 
bon dioxid. 

Anthracite  and  bituminous  coal  are  of  vegetable  origin. 
The  plants  of  the  carboniferous  period  of  geologic  history  were 
transformed  into  coal  by  decay,  heat,  and  pressure.  Coke  is  the 
charcoal  of  bituminous  coal.  Gas  carbon  is  a  form  of  coke  found 
in  gas  retorts  and  molded  to  make  electric  battery  carbons  and 
arc  lights. 

Wood  charcoal  is  used  in  medicine  under  the  official  name 
carbo  ligni.  Charred  bone,  or  bone-black,  called  carbo  animalis, 
contains  the  mineral  ash  as  an  impurity.  When  washed  with 
hydrochloric  acid  the  ash  is  dissolved  out  and  there  is  left  carbo 
animalis  purificatus,  U.  S.  P. 

Uses. — In  therapeutics  charcoal  is  valued  because  it  has  the 
power  of  adsorbing  foul  gases  and  active  oxygen  in  large  volumes. 


ICO 


NON-METALS 


Water  having  an  odor  is  made  sweet,  and  coloring-matters  are 
removed  from  various  liquids  by  filtration  through  charcoal. 
Applied  as  a  poultice  to  foul  ulcers  it  not  only  deodorizes  them, 
but,  from  the  NH3  and  H2S,  by  promoting  their  oxidation,  forms 
acids  which  destroy  and  hasten  the  removal  of  sloughs. 

In  the  chemical  laboratory  charcoal  is  used  as  a  reducing  agent. 
Heated  to  redness  it  not  only  takes  oxygen  from  the  air  to  form 
carbon  oxids,  but  also  from  metallic  oxids,  reducing  the  latter  to 
the  metallic  state.  For  this  property  of  extracting  metals  it  is 
heated  with  ores  in  furnaces. 

Compounds. — Carbon  unites  with  oxygen,  hydrogen,  nitro- 
gen, and  sulphur  to  form  the  very  large  number  of  compounds 
considered  in  the  section  of  this  work  entitled  Organic  Chemistry. 
Only  two  of  its  compounds  are  considered  in  this  place,  the 
monoxid  and  the  dioxid. 

CARBON  MONOXID   (Carbonic  Oxid) 

Formula,  CO.     Molecular  weight,  28. 

Preparation. — (i)  Carbon  monoxid  (CO)  is  prepared  by 
passing  CO2  over  red-hot  coals:  CO2+C=2CO.  (2)  By  inject- 
ing steam  into  red-hot  coals,  making  water-gas:  C  +  H2O  = 
CO  +  H2.  (3)  By  burning  carbon  in  an  insufficient  supply  of 
air.  (4)  By  heating  oxalic  acid  with  sulphuric  acid, 


C2H204 

Oxalic  acid. 


CO 


CO 


T  ^^2 

Carbon  monoxid.  Carbon  dioxid. 


H20, 


the  mixed  gases  being  deprived  of  CO2  by  passing  through  sodium 
hydroxid. 


FIG.  35. — Carbon  monoxid  generated  and  washed  in  sodium  hydroxid. 

Properties.— Carbon  monoxid  is  a  colorless,  tasteless,  inodor- 
ous gas  with  a  specific  gravity  0.967.  It  is  almost  insoluble  in  water 
and  alcohol,  but  absorbed  by  ammoniacal  solutions  of  cuprous 


CARBON    MGNOXliX  '     IOI 

chlorid,  from  which  it  may  be  reseparated  by  heat.  It  burns  to 
CO2  with  a  blue  flame.  This  flame  is  seen  burning  on  the  surface 
of  a  hard-coal  fire,  which  has  at  the  grate  an  insufficient  supply  of 
air  for  complete  combustion  and  hence  burns  first  to  CO  and 
later  at  the  surface  to  CO2. 

Toxicology. — Carbon  monoxid  often  figures  in  cases  of  acci- 
dental poisoning,  as  it  is  the  most  poisonous  constituent  in  the 
deadly  gas  used  in  cities  for  illuminating  purposes  (which  may 
contain  as  much  as  25  per  cent.);  in  that  escaping  into  houses 
from  the  defective  flues  and  open  stoves;  and  in  " white  damp"  of 
mines  and  furnaces.  The  fatal  effects  are  due  to  the  power  of  CO  to 
enter  the  blood  by  the  lungs  and  to  form  with  the  coloring  matter 
a  close  compound,  thus  destroying  the  function  of  carrying  oxygen 
to  the  tissues.  This  function  depends  upon  the  reversible  disso- 
ciation of  oxyhemoglobin. 

HbO         ±5:        Hb         +         O. 

The  compound  with  carbon  monoxid,  HbCO,  is  stable  and  feebly 
dissociable.  This  property,  imparts  an  exceedingly  poisonous 
character  to  an  atmosphere  containing  more  than  o.i  per  cent.; 
when  as  much  as  0.5  per  cent,  is  present  birds  are  killed  in  three 
minutes.  The  symptoms  produced  are  dizziness,  headache, 
nausea,  weakness,  convulsions,  and  coma.  If  a  great  part  of  the 
hemoglobin  be  saturated  with  it,  death  occurs  promptly;  if  there 
be  left  unchanged  enough  to  support  life,  the  symptoms  are  still 
very  grave  and  the  recovery  slow,  debility  and  loss  of  appetite 
persisting  for  days.  It  is  advisable  to  practise  artificial  respiration 
and  inhalation  of  oxygen,  with  hypodermic  injections  of  normal 
salt  solution.1  The  altered  blood  must  be  renewed;  stimulants, 
rest,  and  generous  food  are  the  main  reliance. 

Detection  after  Death. — In  a  case  of  suspected  poisoning 
a  portion  of  the  blood  is  studied  by  the  spectroscope.  If  carbon 
monoxid  be  present,  the  blood  will  be  of  a  persistently  bright-red 
color,  and  the  spectrum  will  show  a  double  absorption  band, 
resembling  the  double  band  of  diluted  oxyhemoglobin,  but  differing 
in  that  it  is  nearer  the  violet  end  (PL  4,  Fig.  i,  e).  It  differs 
further  in  not  being  reduced  to  the  darker  color  of  a  single  band, 
even  when  treated  by  an  ammoniacal  solution  of  ferrous  tartrate. 
When  treated  on  a  white  plate  with  sodium  hydrate,  specific  gravity 
1.3,  the  poisoned  blood  forms  a  clotted  mass,  thin  layers  of  which 
appear  bright  red,  while  normal  blood  turns  to  a  dark  slime  which 
in  thin  layers  is  greenish  brown  (p.  531). 

1  Normal  or  physiologic  salt  solution  is  usually  made  of  the  strength  of  0.7  to 
0.9  per  cent,  of  common  salt,  or  60  gr.  to  the  pint  of  warm  water,  previously  boiled, 
so  as  to  sterilize  it.  One  pint  or  quart  is  injected  every  hour,  as  required,  beneath 
the  skin  of  the  buttocks  or  abdomen. 


102 


NON-METALS 


CARBON  DIOXID   (Carbonic  Acid  Gas,  Carbonic  Anhydrid) 
Formula,  CO2.     Molecular  weight,  44. 

Occurrence.  —  Free  carbon  dioxid  occurs  in  nature:  (i)  Dis- 
solved in  the  ground-water,  and  in  large  proportion  a  constit- 
uent of  the  ground-air,  escaping  from  volcanoes,  accumulating 
in  caves,  wells,  mines,  or  any  excavation.  (2)  As  a  product  of 
putrefaction  and  of  alcoholic  fermentation  it  is  abundant  in  the 
air  of  brewer's  vats.  (3)  It  is  present  in  the  expired  air  of  animals; 
that  exhaled  from  human  lungs  contains  over  4  per  cent,  of  CO2, 
while  fresh  air  contains  only  0.04  per  cent.  (4)  In  the  combustion 
of  wood,  coal,  or  any  organic  substance  the  carbon  is  oxidized  to 
form  CO2.  A  burner  of  illuminating  gas  consumes  nearly  ten 
times  as  much  air  as  a  man,  and  produces  six  times  as  much  carbon 
dioxid. 

Preparation.—  Carbon  dioxid  can  be  obtained  by  the  action 
of  any  non-volatile  acid  on  any  carbonate;  but  the  most  convenient 
source  is  white  marble,  a  crystalline  calcium  carbonate,  from  which 
CO2  is  evolved  by  the  action  of  hydrochloric  acid. 


CaCO3     H 

Calcium  carbonate. 


2HC1     =      CaCl2 

Calcium  chlorid. 


HO 


CO. 


The  apparatus  used  is  the  same  as  that  for  the  preparation  of 
hydrogen  (Fig.  28).     As  one  volume  of  water  dissolves  an  equal 


FIG.  36.— Pouring  CO2  downward. 

volume  of  the  gas  it  is  wasteful  to  use  the  pneumatic  trough. 
Being  one  half  heavier  than  air,  it  is  easily  collected  by  downward 
displacement. 


CARBON    DIOXID  103 

Properties. — Carbon  dioxid  is  a  colorless,  suffocating  gas  with 
a  slightly  acid  taste  and  smell,  having  a  specific  gravity  of  1.529. 
Under  a  pressure  of  50  atmospheres  at  15.5°  C.  (60°  F.)  it  is  con- 
densed to  a  transparent  liquid.  It  will  not  burn,  nor  will  it  sup- 
port combustion,  but  heated  to  1300°  C.  (2370°  F.)  it  breaks  up  into 
CO  and  O.  The  chemical  fire  extinguisher  is  an  apparatus  for 
generating  CO2  under  pressure,  from  which  the  gas  is  discharged 
in  enormous  volumes.  Under  the  names  of  "black  damp"  and 
" choke-damp"  it  is  an  exhalation  in  mines,  dreaded  for  its  suffo- 
cative  effects.  Sometimes  there  flows  from  the  seams  of  coal 
a  natural  gas  known  as  "  fire-damp,"  containing  methane  CH4, 
ethane  C2H6,  and  hydrogen.  In  the  pits  of  the  mines  it  makes 
with  air  an  explosive  mixture.  To  prevent  the  accumulation  of 
these  gases  ventilators  are  kept  going  constantly  so  as  to  displace 
them  with  air.  If  this  is  not  done  a  lighted  candle  or  match 
ignites  the  mixture  with  deadly  violence,  producing  carbon  dioxid 
or  the  "after-damp." 

Davy's  safety-lamp  has  a  chimney  of  wire  gauze  through  which 
the  flame  cannot  pass  to  ignite  the  explosive  gases  of  the  mine. 
The  metal  of  the  gauze  cools  the  flame  below  the  point  of  ignition. 

Aqua  acidi  carbonici,  or  soda  water,  is  a  solution  of  CO2  in  water 
under  a  pressure  of  5  atmospheres.  At  ordinary  pressure  water 
dissolves  an  equal  volume  of  gas  and  takes  up  this  amount  more 
for  each  addition  of  one  atmospheric  pressure.  On  opening  the 
bottle  the  excess  escapes  as  4  volumes  of  gas  (Carbonic  Acid,  p. 
191). 

Detection. — Carbon  dioxid  extinguishes  a  flame  and  forms 
a  white  precipitate  of  carbonates  when  passed  through  the  hy- 
droxids  of  calcium  or  barium. 

Ca(OH)2        +         CO2  CaCO3         +         H2O. 

Calcium  hydroxid.  Calcium  carbonate. 

In  a  mixture  of  different  gases,  subjected  to  the  absorbing 
powers  of  potassium  hydroxid,  a  lessening  of  volume  denotes 
CO2,  and  the  amount  of  loss  is  a  measure  of  the  quantity  of  that 
gas.  By  aspirating  a  measured  amount  of  any  air  through  a  weight 
absorption  tube  containing  potassium  hydroxid,  the  amount  of 
CO2  is  shown  by  the  increase  of  weight. 

The  test  fluid  used  by  Fitz  is  dilute  calcium  hydroxid  colored 
pink  by  phenolphthalein.  Measured  quantities  of  air'  are  agi- 
tated with  this  fluid  until  it  is  decolorized.  A  table  gives  the  CO2 
in  parts  per  10,000  of  the  air  used. 

Tests  for  Carbonates. — (i)  Carbonates  treated  with  hydro- 
chloric acid  evolve  CO2  with  effervescence;  the  CO2  passed  into 
lime-water  produces  a  milky  precipitate,  CaCO3. 


104  NON-METALS 

(2)  In  neutral  solutions  of  carbonates,  barium  chlorid  causes 
a  white  precipitate  of  barium  carbonate,  which  dissolves  in  acids 
with  effervescence. 

Constant  Proportion  of  C02  in  the  Atmosphere.— A  full- 
grown  man  breathes  every  day  about  10,000  liters  of  air,  of  which 
he  absorbs  about  500  liters  of  oxygen  and  exhales  about  450  liters 
of  carbon  dioxid.  Every  breath  contains  enough  CO2  to  make 
a  milky  precipitate  when  expired  through  lime-water.  The 
average  amount  of  CO2  present  in  the  open  air  of  the  country 
is  0.04  per  cent.,  or  4  parts  in  10,000.  Notwithstanding  the 
enormous  quantities  poured  into  the  air  from  volcanoes,  fermen- 
tations, respiration  of  animals,  and  combustion,  the  percentage  of 
CO2  is  constant.  There  is  a  state  oj  equilibrium  in  which  the  air 
continuously  loses  as  much  CO2  as  it  receives.  Some  of  the  carbon 
dioxid  is  dissolved  by  the  surface  waters  of  the  earth  and  fixed  by 
the  animal  organisms — corals,  shell-fish,  etc.,  whose  skeletons  and 
shells  make  deposits  of  earthy  carbonates.  The  greater  part, 
however,  is  removed  by  plants  which  absorb  CO2  through  their 
leaves  and  roots.  In  the  leaf  are  cells  like  the  leukocytes  of  the 
blood  of  animals.  They  contain  green  granules  of  chlorophyll 
which  are  energized  by  sunlight,  but  which  are  inactive  in  the  dark. 
The  leaf  serves  as  a  laboratory  in  which  the  chemical  powers  of 
the  sunlight  decompose  the  CO2,  the  plants  retaining  the  carbon 
and  exhaling  oxygen  in  volumes  equal  to  the  absorbed  gas.  This 
restoration  of  oxygen  compensates  for  the  amount  of  that  gas 
consumed  in  the  various  processes  that  produce  CO2. 

Circulation  of  Carbon.— The  life  of  organisms  is  sustained 
by  the  transformation  of  energy,  most  of  which  is  the  energy 
obtained  by  the  oxidation  of  carbon.  Plants  lead  a  double  life. 
They  live  and  grow  by  oxidizing  the  food  the  sun  forms  by  day 
in  the  leaf  when  they  exhale  oxygen.  In  the  night  when  food- 
making  ceases,  but  growth  continues,  they  exhale,  like  an  animal, 
a  perceptible  amount  of  CO2.  Only  by  oxidizing  the  carbon  com- 
pounds built  up  by  plants,  such  as  sugar,  starch,  oil,  and  gluten, 
can  animals  support  their  vital  activities.  The  radiant  energy 
expended  by  the  sun  is  stored  up  by  plants  in  amounts  sufficient 
not  only  for  self-maintenance,  but  also  for  the  supply  of  energy  to 
repair  the  waste  occasioned  by  the  life-process  of  all  other  organ- 
isms. The  herbivorous  animals  consume  carbonaceous  food 
derived  from  plants,  the  carnivora  in  turn  get  their  energy  by 
feeding  upon  like  material  stored  in  the  flesh  of  the  plant  eaters. 

In  the  oxidation  product,  CO2  of  the  expired  breath,  animals 
return  to  the  air  the  carbon  which  it  had  lost.  The  CO2  is  carried 
from  the  animal  tissues  to  the  lungs  in  combination  mainly  with 
sodium  bicarbonate.  In  the  lungs  the  bicarbonate  breaks  up,. 


CARBON    DIOXID  IO$ 

yielding  the  carbonates  again  and  giving  CO2  and  H2O  to  the 
expired  breath,  thus  reversing  the  reaction. 

2NaHCO3     5±1     Na2CO3     +      CO2     +      H2O. 

Sodium  bicarbonate.  Sodium  carbonate. 

Each  of  the  two  living  kingdoms  of  nature  supports  the  other  in  an 
eternal  circuit  of  energy,  obtained  originally  in  kinetic  form  from 
the  sun's  rays  and  carried  potentially  by  the  carbon,  on  the  one 
hand,  and  the  oxygen,  on  the  other.  The  production  of  wood  (cel- 
lulose) and  the  energy  used  is  in  the  sense  of  the  equation: 

6CO2    +    5H2O    +    671,000  calories   7^    C6H10O5    +    6O2. 

A  part  of  the  carbon  of  plants  which  does  not  soon  return  to  the 
air  is  preserved  in  the  storehouse  of  the  soil  as  combustible  sub- 
stance. A  peat  deposited  in  bogs  or  in  the  fossilized  form  of  coal, 
the  carbon  reappears  in  aftertimes  to  heat  the  boiler  of  the  steam 
engine,  and  thus  becomes  the  most  abundant  store  of  energy  used 
in  the  mechanic  arts. 

The  average  composition  of  air  may  be  said  to  be  in  100  vols.: 

When  inspired.  When  expired. 

Oxygen  ..................................  20.60  vols.  16  vols. 

Nitrogen  .................................  76.90  77 

Argon  ...................................    i.oo     "  i      " 

Carbon  dioxid  ............................   0.04     "  4     " 

Aqueous  vapor  (about)  ....................    1.46     "  2      " 

Ammonia  ........................  "| 

Ozone 


r  races. 

Marsh  gas  .......................    ( 

Sulphurous  anhydrid  ..............    j 

Sulphuretted  hydrogen  (in  towns)          J 

In  the  proportion  of  argon  given  above  is  included  its  con- 
geners, helium,  neon,  crypton,  and  xenon. 

Excess  of  CO2  in  Air.  —  When  the  circulation  and  diffusion  of 
the  air  is  interfered  with  by  confinement  in  caves,  wells,  mines, 
vats,  or  badly  ventilated  rooms,  it  accumulates  CO2,  and  when 
the  proportion  reaches  0.7  per  cent,  it  is  said  to  be  contaminated. 
If  the  CO2  be  derived  from  respiration  or  combustion  the  air  at 
the  same  time  loses  oxygen,  so  that  an  increase  of  CO2  from  these 
sources  is  most  serious  in  its  influence  upon  health. 

The  cubic  space  for  dormitories  allowed  each  person  should 
be,  for  the  healthy,  at  least  400  cu.  ft.;  for  the  sick,  occupying  the 
same  room  day  and  night,  850  cu.  ft.;  for  lying-in  cases  and  those 
having  offensive  diseases,  1200  cu.  ft.  To  calculate  the  largest 
number  of  persons  that  ought  to  sleep  in  a  room,  measure  the 
length,  breadth,  and  height  of  the  room  and  multiply  them  to 
get  the  cubic  contents.  Divide  the  cubic  contents  by  400  and 
the  quotient  is  the  number  of  healthy  occupants,  which  should 


106  NON-METALS 

not  be  exceeded  if  we  would  avoid  contamination  of  the  air  from 
overcrowding. 

Poisonous  Effects. — Pure  carbon  dioxid  causes  instant  suffo- 
cation by  spasm  of  the  glottis.  When  the  CO2  is  simply  added  to 
the  air,  as  in  the  industry  of  making  soda-water,  or  as  in  the  dis- 
charge into  free  air  from  carbonated  springs  and  other  natural 
sources,  an  addition  of  10  to  15  per  cent,  will  render  the  air  poison- 
ous, but  not  immediately  fatal.  A  candle  would  still  burn  in  this 
air,  though  dimly,  but  when  the  proportion  reaches  16  per  cent, 
the  flame  is  extinguished.  It  would  be  fatal  to  go  into  any  con- 
fined space  where  a  candle  will  not  burn.  When  the  contamina- 
tion of  confined  air  is  due  to  respiration  or  combustion,  and  the 
reduction  of  oxygen  corresponds  to  the  increase  of  CO2,  we  feel 
oppressed  by  o.i  per  cent.,  and  instinctively  escape  from  it. 
Greater  discomfort  is  produced  by  i  per  cent.;  headache,  dizziness, 
.and  nausea  may  be  caused  by  2  per  cent.;  an  atmosphere  containing 
3  per  cent,  does  not  kill,  though  it  causes  profound  disturbance  of 
health,  but  5  per  cent,  may  be  fatal  from  asphyxia. 

Treatment. — The  indication  is  to  get  into  the  lungs  a.  large 
amount  of  pure  air  or  oxygen  as  quickly  as  possible.1  To  do 
this,  the  patient  must  be  instantly  removed  to  fresh  air,  and  arti- 
ficial respiration  practised  with  inhalations  of  oxygen.  Respiration 
is  stimulated  by  rhythmic  pressure  on  the  chest,  traction  of  the 
tongue,  slapping  with  a  wet  towel,  galvanism,  and  friction  of  the 
extremities.  These  measures  must  be  kept  up  for  an  hour,  if 
necessary.  When  breathing  is  established,  warm  applications 
should  be  made  to  the  extremities,  and  the  body  well  wrapped 
in  woolens,  while  coffee  or  brandy  is  administered  internally. 

The  Atmosphere. — The  proportionate  mixture  in  the  atmo- 
sphere has  been  stated  above.  The  20.6  per  cent,  of  oxygen  sup- 
ports animal  life;  the  76.9  per  cent,  of  nitrogen  serves  to  dilute 
the  oxygen;  the  0.04  per  cent,  of  CO2  and  the  trace  of  ammonia 
nourish  plants;  water,  to  the  extent  of  1.46  per  cent.,  favors  the 
.absorption  of  these  foods  and  ozone  purifies  the  air. 

Physical  Properties. — A  liter  of  air  weighs  1.293  gm-  Having 
covered  an  open  receiver  with  the  hand  and  removed  the  air  with 
an  air-pump,  the  pressure  of  the  atmosphere  is  felt  as  a  force  of 
15  Ibs.  on  every  square  inch  (1033.3  gm-  on  every  square  cen- 
timeter). The  whole  body  must  support  the  pressure  of  several 
tons,  and  that  it  is  able  to  do  so  is  due  to  the  fact  that  the  pressure 

1  It  often  happens  that  the  patient  is  first  seen  lying  unconscious  at  the  bottom  of 
;a  well  or  pit  or  vat.  Rescue  seems  impossible  because  others  descending  are 
instantly  suffocated.  In  such  cases  great  success  has  followed  the  following  pro- 
cedure: A  condenser  of  oxygen,  holding  240  gallons  of  the  gas  compressed  in  a 
cylinder,  is  obtained  from  a  hospital  or  a  theater  using  oxygen  for  the  oxycalcium 
light.  Through  a  hose  reaching  to  the  bottom  of  the  pit  the  gas  is  discharged  not 
•only  to  revivify  the  patient,  but  to  displace  the  CO2,  so  that  others  can  descend  to 
his  assistance. 


CARBON    DIOXID  IO7 

is  exerted  equally  in  all  directions,  thus   canceling   the    pressure 
on  any  one  point. 

The  variations  of  atmospheric  pressure  from  day  to  day,  or  at 
different  heights,  are  measured  by  the  barometer.  In  its  simplest 
form  this  instrument  is  a  strong,  straight  glass  tube,  about  33  in. 
(800  mm.)  in  length,  closed  at  the  top.  The  lower  end,  which  is 
open,  dips  into  a  small  cistern  of  mercury.  This  tube  is  first  filled 
with  mercury  and  then  inserted  in  the  cistern  with  the  open  end 
under  the  liquid.  The  mercury  of  the  tube  falls  to  a  point  about 
30  in.  (760  mm.)  from  the  level  of  the  cistern.  The  unoccupied 
space  above  the  mercury  is  a  vacuum.  The  pressure  of  the  air 
outside  upholds  the  column  inside.  As  the  air  grows  heavier 
the  pressure  forces  the  mercury  higher;  as  the  air  declines  in 
pressure,  the  mercury  falls.  In  ascending  a  mountain  the  column 
of  air  above  is  reduced  in  height,  and,  therefore,  the  barometric 
column  falls  i  in.  for  every  900  ft.  of  elevation. 

Gases  are  highly  compressible,  shrinking  in  volume  regularly 
as  the  pressure  increases  (Boyle's  law).  On  the'1  other  hand,  the 
volume  increases  regularly  with  equal  additions  of  absolute  tem- 
perature (Charles'  law).  To  compare  the  volumes  of  gases  observed 
at  different  times,  it  is  necessary  that  the  pressure  of  the  air  and 
the  temperatures  at  the  times  of  observation  be  alike.  As  this  is 
practically  impossible  from  day  to  day,  or  hour  to  hour,  it  has  been 
agreed  to  reduce  the  observed  volumes  of  gases  to  standard  condi- 
tions. By  means  of  a  formula  the  observation  is  converted  to  the 
standard  barometric  pressure  of  760  mm.,  and  at  the  standard  tem- 
perature of  o°  C. 

V(b  -  w) 


V  = 


760(1  +  0.00366  T) 


In  this  formula:  V  =  volume  required;  V  =  the  volume  ob- 
served; b  =  barometer  in  mm.;  w  =  tension  of  aqueous  vapor 
(table,  p.  40);  T  --=  observed  temp.  Centigrade  (p.  30,  footnote). 

Recent  studies  on  the  expansion  of  very  dilute  gases  show  that 
at  a  certain  stage  of  dilution  the  ability  to  expand  is  much  less- 
ened. This  justifies  the  inference  that  the  air  does  not  extend 
indefinitely  into  space,  becoming  progressively  more  attenuated, 
but  that  at  a  distance  of  two  hundred  miles,  more  or  less,  it  has 
a  definite  limit. 

When  air  is  compressed  2000  pounds  on  the  square  inch, 
cooled  with  cold  water,  and  then  permitted  to  expand,  it  makes 
a  low  temperature  for  cooling  another  portion  of  compressed  air. 
This  in  expanding  cools  another  portion  to  a  much  lower  tem- 
perature and,  repeating  this  cycle  of  operations  for  the  third  time, 
the  compressed  air  in  expanding  through  a  small  opening  is  cooled 
below  its  critical  point  and  liquefies. 


IDS  NON-METALS 

Liquid  air  can  be  obtained  in  any  quantity  by  the  expenditure 
of  power.  It  is  a  bluish  mobile  liquid  boiling  at  —190°  C. 
(  —  376°  F.),  and  is  used  for  procuring  that  temperature  for  experi- 
mental purposes.  Immersed  in  it  mercury  freezes  so  hard  that 
a  piece  can  be  used  to  hammer  a  nail;  rubber  and  meat  become 
as  brittle  as  thin  glass,  alcohol  solidifies  like  ice.  Many  forms 
of  bacteria  survive  this  exposure  with  only  a  temporary  suspen- 
sion of  vitality,  and  seeds  of  grain  and  peas  after  hours  of  immer- 
sion showed  subsequent  power  of  germination.  As  the  air  boils, 
the  first  more  volatile  portion  extinguishes  a  flame;  it  is  nitrogen. 
After  a  time  the  boiling  vapor  starts  a  glowing  ember  into  flame, 
and  we  find  that  the  liquid  left  is  nearly  pure  oxygen,  which  has 
a  higher  boiling-point  than  the  nitrogen. 


CHEMICAL  PHILOSOPHY 

IN  another  place  (p.  70)  illustrations  have  been  given  of  Dalton's 
first  law,  that  of  Definite  Proportions:  i.  e.,  A  definite  compound 
always  contains  the  same  elements,  united  in  the  same  proportions. 

There  are  five  compounds  of  nitrogen  and  oxygen.  The  form- 
ulas, names,  and  compositions  by  weight  are  as  follows: 

N.  O. 

N2O  .28  1 6  Nitrous  oxid. 

NO  -14  1 6  Nitric  oxid. 

28  48  Nitrogen  trioxid  or  Nitrous  anhydrid. 

28  64  Nitrogen  tetroxid  or  Nitrogen  peroxid. 

28  80  Nitrogen  pentoxid  or  Nitric  anhydrid. 

These  compounds  are  illustrations  of  Dalton's  second  law,  that 
of  Multiple  Proportions:  When  two  bodies,  simple  or  compound, 
unite  in  several  proportions,  the  weight  of  one  being  constant,  the 
weights  of  the  other  vary  according  to  a  simple  ratio.  When  com- 
posed of  two  elements  they  are  said  to  be  binary.  In  nomen- 
clature the  name  of  the  electropositive  element  in  full  is  placed 
first;  then  follows  the  name  of  the  electronegative  element,  with 
a  suffix  derived  from  the  Greek  numerals  and  the  termination  id. 
In  an  older  method  the  name  of  the  electropositive  element  was 
modified  by  adding  -ic  or  -ous  to  the  first  syllable  of  the  electro- 
positive element.  Nitrous  means  less  and  nitric  means  more  of 
the  other  or  electronegative  element.  For  the  other  compounds 
the  prefix  hypo-  means  less  and  per-  means  more  of  the  electro- 
negative element. 

In  union  with  H2O,  the  first,  third,  and  fifth  of  the  above-named 
form  acid  ternary  compounds  of  three  elements,  nitrogen  with 
hydrogen  and  oxygen,  as  follows: 

H2N2O2  or  HNO Hyponitrous  acid. 

H2NA°rHN02 Nitrous  acid. 

H2N2O6orHNO3 Nitric  acid. 


ATOMIC    THEORY  109 

There  is  another  generalized  statement  of  facts,  developing 
logically  from  the  first  and  second  laws — Equivalent  Propor- 
tions: The  proportions  in  which  two  or  more  bodies  unite  with 
another  is  either  the  same  as  that  in  which  they  unite  with  them- 
selves or  a  simple  multiple  oj  it. 

ATOMIC  THEORY 

In  studying  the  phenomena  of  allotropism  of  oxygen  and 
carbon  (see  pp.  74  and  99)  the  conclusion  becomes  inevitable  that 
nature,  as  we  know  it,  behaves  as  if  it  were  composed  of  minute 
separate  particles,  variously  grouped  in  different  bodies  and  in 
allotropic  forms  of  the  same  substance.  This  conception  came 
early  in  the  history  of  thought,  the  first  definite  statement  of  the 
doctrine  of  atoms  being  attributed  to  Democritus  (400  B.  C.).  As 
further  developed  by  Lucretius,  it  may  be  summarized  as  follows: 
The  bodies  which  we  see  and  handle,  which  we  can  break  in  pieces 
and  destroy,  are  composed  of  smaller  bodies  which  we  cannot 
see  nor  handle,  which  are  always  in  motion,  are  centers  of  energy, 
and  are  not  broken  by  us  nor  in  any  way  destroyed.  In 
the  recent  century  of  great  chemical  and  physical  discoveries 
each  new  fact  has  found  a  place  in  the  structure  of  this  theory. 
All  attempts  have  failed  to  account  for  chemical  phenomena  on 
the  opposed  hypothesis  of  the  homogeneous  structure  of  matter. 
The  only  consistent  view  of  matter  is  that  it  is  not  uniform  and 
continuous  throughout,  but  grained.  The  grains  are  molecules 
(see  p.  28)  which  have  still  smaller  constituents,  atoms.  The 
atoms  are  undestroyed  by  the  chemical  force  which  keeps  them 
combined  in  molecules  and  which  controls  their  movements  and 
associations.  To  these  properties  Dalton,  in  1808,  proposed  that 
there  be  added  others,  to  wit:  (i)  all  the  atoms  of  any  one  element 
have  equal  mass  or  weight;  (2)  the  atoms  of  different  elements 
have  different  weights;  (3)  the  atomic  weights  be  related  as  are 
the  combining  weights. 

As  it  is  not  divided  in  chemical  reactions,  the  atom  is  the 
smallest  quantity  of  an  element  that  can  enter  into  chemical 
combination.1  When  two  elements  combine,  one  atom  of  one 

1  Recent  study  of  radio-active  metals  (p.  250)  has  established  certain  facts  of 
wide  range  that  do  not  fit  into  the  atomic  theory  unless  the  intellectual  conception 
of  the  atom  be  elaborated.  The  new  conception  symbolizes  the  new  facts  by  giving 
a  mechanical  interior  structure  to  the  atom.  It  is  conceived  that  in  the  sphere  of  the 
atom  are  a  number  of  gyrating  corpuscles  (electrons  with  a  mass  one  i  Sooth  that 
of  the  hydrogen  atom) ,  acting  as  a  unit  because  in  a  state  of  equilibrium  which 
resists  the  separating  power  of  chemical  operations  and  hence  just  so  far  justifies 
the  assumption  that  atoms  are  indivisible.  The  atom-complexes  of  the  radio-active 
elements,  however,  are  in  a  state  of  unstable  equilibrium,  exhibiting  energy  in  the 
form  of  heat,  light,  etc.,  while  the  atom-complex  as  a  whole,  losing  some  electrons, 
changes  in  properties  as  it  declines  in  mass  to  stable  forms  which  are  permanent. 


HO  NON-METALS 

element  is  placed  in  juxtaposition  with  one  or  more  atoms  of 
the  other.  It  follows  that  the  weights  of  two  elements  uniting 
will  be  in  the  same  proportion  as  the  constant  weights  of  their 
atoms.  This  is  the  explanation  of  the  law  of  definite  or  con- 
stant proportions.  Thus,  if  the  relative  weights  of  atoms  of 
sodium  and  chlorin  are  as  23  to  35,  and  combination  is  simply 
juxtaposition,  then  sodium  chlorid  can  contain  its  elements  only 
in  the  proportion  of  23  parts  of  sodium  to  35  of  chlorin. 

Again,  if  one  element,  C,  forms  two  compounds  with  another 
element,  O,  the  first  one  of  which  contains  one  atom  of  C  and 
one  atom  of  O  and  the  second  contains  one  atom  of  C  and  two 
of  O,  it  is  plain  that  the  masses  of  O  which  unite  with  the  fixed 
mass  of  C  must  be  in  a  ratio  by  a  whole  number.  Thus,  12 
weights  of  C  unite  with  16  of  O  to  make  CO.  But  as  O  forms 
another  compound  to  the  constant  weight  12  of  C,  it  can  not  have 
less  than  16  of  O,  for  that  would  be  to  split  an  atom,  which  is 
postulated  to  be  impossible.  The  mass  of  O  must  be  either  the 
first  weight,  16,  or  some  simple  multiple,  such  as  i  :  2,  so  it  takes  32 
of  O  and  forms  OCO  or  CO2.  By  almost  universal  consent 
chemists  refer  all  the  facts  of  their  science  to  the  one  general  law 
above  stated  —  that  is,  that  elements  are  composed  of  atoms  having 
the  same  weights  for  the  same  kind,  but  different  weights  for 
different  kinds.  By  means  of  this  law  the  chemist  determines 
not  only  the  nature  and  number  of  the  atoms  in  a  molecule,  but 
also  their  arrangements.  In  no  other  way  can  we  account  for  the 
compounds  called  isomeric,  which  show  that  two  or  more  distinct 
substances  may  yet  have  the  same  number  of  the  same  atoms  in 
the  molecule. 

As  stars  in  a  system  are  kept  in  place  by  gravitation,  so  in  a 
complex  molecule  atoms  in  various  groups  are  held  together  by 
chemical  attraction.  A  molecule  of  common  alcohol,  also  that  of 
methyl-ether,  contains  one  atom  of  oxygen,  two  of  carbon,  and  six 
of  hydrogen.  There  is  sound  experimental  basis  for  the  conclu- 
sion that,  although  they  have  the  same  elements  in  the  same  pro- 

CH3 
portion,  the  groups  of  atoms  in  methyl-ether  are  (V  and    of 


alcohol  are  HO.CH2.     Powerful  external  forces  may  break  up  the 

I 
CH 


3 


mutual  attraction  of  large  groups,  but  only  to  prove  that  the  mem- 
bers of  a  smaller  group  have  the  greatest  attraction  for  one  another 
by  the  persistence  of  the  original  arrangement  of  their  atoms.  The 
atoms  of  the  group  CH3  remain  subject  to  each  other's  influence 
through  many  vicissitudes  and  varying  associations. 


ATOMIC    THEORY  III 

The  atomic  weight  (A.  W.)  of  an  element  is  the  weight  of  one 
atom  of  that  element  as  compared  with  the  weight  of  an  atom 
of  hydrogen.  (For  "subatomic  matter,"  see  p.  250.) 

The  molecular  weight  (M.  W.)  of  a  substance  is  the  weight  of 
its  molecule,  as  compared  with  the  weight  of  an  atom  of  hydrogen. 

As  all  gases  are  affected  equally  by  temperature  and  pressure 
their  molecular  constitution  must  be  alike.  The  law  oj  Avogadro 
assumes  that  equal  volumes  oj  all  gases  at  the  same  temperature  and 
pressure  contain  an  equal  number  of  molecules.  It  follows  from 
this  law  that  the  molecular  weights  of  gases  are  proportional  to 
the  weights  of  equal  volumes — that  is,  to  their  specific  gravities. 
The  molecular  weight  is  the  sum  of  the  atomic  weights;  hence 
if  hydrogen  be  the  unit,  its  molecular  weight  is  2,  there  being  2 
atoms  in  its  molecule.  To  obtain  the  molecular  weight  of  another 
gas,  all  that  is  necessary  is  to  double  its  density.  The  vapor 
density  is  the  specific  gravity  with  hydrogen  =i.  M.  W.  =  2X 
V.  D.  (H=i).  Expressed  in  terms  of  ordinary  specific  gravity 
(air=  i),  we  must  allow  for  the  fact  that  air  is  14.43  times  heavier 
than  hydrogen;  then  the  molecular  weight  of  a  gas  equals  the 
specific  gravity  multiplied  by  14.43  and  by  2;  or  M.  W.  =  28.86X 
S.  G.  (air=i).  Thus:  the  density  of  ozone  (H=i)  is  approx- 
imately 24,  which  when  doubled  becomes  48.  The  weight  of  each 
atom  being  16,  which  is  one-third  of  48,  there  must  be  three  atoms 
in  its  molecules  and  its  formula  must  be  O3. 

From  what  has  been  said  above  it  might  be  expected  that  in 
chemical  combinations  of  elementary  gases  the  volumes  entering 
into  the  union  would  hold  some  simple  relation  to  each  other.  In 
fact  this  is  Gay-Lussac's  law.  Moreover,  the  product  of  the  reac- 
tion (the  compound  gas)  has  the  volume  oj  a  simple  multiple,  usu- 
ally 2,  even  when  the  original  single  volumes  were  3  or  4.  For 
example:  when  united, 

1  vol.  of  hydrogen  -j-  I  vol.  of  chlorin  yield  2  vols.  of  HC1. 

2  vols.  "  -1-  *  sulphur     "     2     "          H2S. 

2  "  "  -f-  I       '•       oxygen     "     2     "          steam. 

3  "  '«  -|-  i       "       nitrogen   "     2     "         NH3. 

Summary. — A  molecule  is  the  smallest  particle  of  a  substance 
that  exists  free  and  stable. 

An  atom  is  Lhe  smallest  characteristic  part  of  an  element  that 
is  combined  in  the  molecule  by  chemical  action. 

A  compound  is  composed  of  molecules  which  contain  two  or 
more  different  kinds  of  atoms  united. 

An  element  is  composed  of  molecules  which  contain  but  one 
kind  of  atom. 

An  electron  is  the  negatively  electrified  particle  contained  in  all 
atoms,  and  of  which  there  are  at  least  1000  in  a  hydrogen  atom. 


H2  NON-METALS 

Chemical  union  is  due  to  electric  attractions;  electronegative 
ions  have  a  few  more  electrons  than  exactly  balance  their  positive 
electricity;  electropositive  ions  have  a  few  less.  When  they 
meet  they  unite  in  a  neutralized  molecule  (pp.  46  and  50). 

Symbols  and  Formulas. — In  place  of  records  of  composi- 
tion and  lengthy  descriptions  of  reactions  it  has  been  found  con- 
venient to  use  a  shorthand  system  of  symbols  and  equations. 
The  symbol  of  an  element  is  usually  the  initial  letter  of  its  name 
(English  or  Latin);  when  the  names  of  two  or  more  elements 
have  the  same  initial,  a  second  letter  is  added  in  smaller  type. 
This  second  letter  is  the  next  vowel  or  a  prominent  consonant. 
Thus,  Boron,  Barium,  Berryllium,  Bismuth,  and  Bromin  have  the 
symbols  B,  Ba,  Be,  Bi,  and  Br,  respectively.  The  choice  of  the 
single  initial  is  given  to  the  non-metal — in  this  case  to  Boron. 

The  formula  of  a  compound  is  made  by  printing  as  close  as 
the  types  permit  the  symbols  of  the  constituent  elements:  thus, 
copper  oxid  is  CuO. 

The  chemical  symbol  has  a  much  more  complex  function  than 
that  of  an  algebraic  one,  like  x  and  y,  which  stand  for  simple 
quantities.  The  chemical  symbol  represents,  first,  the  name  of  an 
element;  second,  one  atom;  third,  a  constant  definite  proportion, 
called  the  atomic  weight;  fourth,  a  single  gas  volume.  Thus, 
O  stands  for  oxygen,  i  atom,  16  weights,  and  i  volume. 

The  formula  of  a  compound  denotes  the  name  of  its  elements, 
the  atoms  in  one  molecule,  the  constant  molecular  weight,  and 
two  gas  volumes. 

Thus,  H2O2  stands  for  hydrogen  dioxid,  4  atoms  in  its  mole- 
cule, a  molecular  weight  of  34  (2  for  the  H2  and  32  for  the  O2), 
and  2  gas  volumes.  It  will  be  observed  that  when  the  molecule 
contains  two  or  more  atoms  of  the  same  kind  the  formula  shows 
it  by  the  small  coefficient  following,  placed  below  the  line.  Thus, 
H2O,  CO2. 

If  it  be  desired  to  express  more  than  one  molecule  of  a  com- 
pound, a  large  figure  is  used  as  a  coefficient  before  the  formula; 
thus,  2HNO3  represents  not  simply  2  atoms  of  hydrogen,  but  2 
molecules  of  nitric  acid. 

Three  different  kinds  of  formulas  may  be  used  to  represent 
the  same  compound.  When  it  is  desired  to  express  the  com- 
position only,  an  empiric  formula  is  used,  which  gives  in  the 
smallest  number  the  proportions  of  the  atoms.  A  molecular  for- 
mula is  a  rational  attempt  to  give  the  actual  number  of  atoms  in 
the  molecule,  and  this  may  be  a  multiple  of  the  empiric  formula. 
When  there  is  experimental  ground  for  assuming  that  the  inter- 
nal grouping  of  the  atoms  is  known,  the  facts  are  indicated  by 
the  arrangement  of  the  symbols  of  the  atoms,  thus  making  the 


PLATE   i. 


"!5* 

^W  ^fe^ft^fe 

v^ 


»ChU 

ATOMIC  THEORY  OF  A  HYDROCARBON  FLAME. 

The  red  ciscs  are  oxygen  atoms,  the  black  are  carbon,  the  blue  are  hydrogen  ; 
the  black  circles  in  the  yellow  zone  are  incandescent  carbon  atoms  emitting  light. 
The  products  of  the  combustion  are  water  and  carbon  dioxid. 


ATOMIC    THEORY  113 

formula   constitutional.     Thus,   ferric   hydroxid   may   be   denoted 
by  either  of  the  following  formulas: 

Empiric  and  molecular FeH3O3. 

Constitutional       Fe(OH)3. 

Nascent  State. — When  an  element  has  just  been  released  from 
combination,  it  is  observed  to  have  more  powerful  attractions  than 
are  shown  by  it  after  the  first  moment  of  new  birth  has  passed. 
This  transition  phase  of  higher  energy  has  received  the  name 
nascent  state.  It  is  often  purposely  produced  to  secure  the  highest 
capability  of  the  element  for  effecting  chemical  changes.  Ac- 
cording to  the  atomic  theory,  the  transient  state  is  one  of  single 
atoms  energetically  drawing  others  to  them.  With  free  affinities 
they  are  ready  for  fresh  unions.  Finding  no  dissimilar  element 
to  attract,  they  must  at  last  combine  with  like  companions  to 
make  stable  molecules  of  the  same  elements.  The  atoms  are 
now  without  free  affinities,  tied  up  in  a  combination  which  must 
be  broken  afresh  before  they  can  form  another  with  atoms  of  a 
different  element. 

The  properties  ascribed  to  the  chemical  atom  express  its  actual  re- 
ations.  With  its  intra-atomic  gyrating  electrons  it  is  a  conception 
in  the  highest  degree  useful  fbr  a  working  chemist  as  well  as  for 
the  philosopher.  No  other  theory  has  harmonized  so  many  chem- 
ical facts,  or  has  proved  more  fruitful  in  discoveries  than  this. 

A  graphic  picture  is  here  shown  (Plate  i)  of  what  the  chemist 
imagines  to  occur  when  he  explains  the  burning  of  common  illu- 
minating gas  in  a  luminous  flame: 

CH4        +       2O2  CO2       +       2H2O. 

It  must  be  remembered  that  in  this  plate  nothing  is  postulated 
of  the  atom  as  to  its  color  or  form  or  relations  in  space. 

Carbon  atoms  are  represented  by  black  discs,  which  become 
bright  at  a  high  heat;  hydrogen  atoms  are  blue;  oxygen,  red. 
These  colors  serve  simply  to  distinguish  the  elements. 

Molecules  of  CH4  stream  out  at  the  burner,  a  match  heats  it 
to  the  point  required  to  unite  it  with  oxygen.  The  free  oxygen 
of  the  air  in  molecules,  when  heated,  dissociates  into  atoms, 
which  at  once  unite  with  the  hydrogen  of  CH4  to  form  molecules 
of  H2O.  Their  union  causes  heat  sufficient  to  raise  the  carbon 
atoms  of  CH4  to  incandescence,  furnishing  light  as  they  pass 
through  the  hot  zone.  At  the  outer  margin  they  meet  oxygen 
atoms  heated  and  combine  with  them  to  form  CO2.  At  the  center 
is  the  combustible  gas  CH4  yet  unburned,  surrounded  by  a  cone 
of  incandescent  carbon  which  deposits  soot  on  a  cold  surface 


114  NON-METALS 

and  on  the  outer  edge  is  the  hottest  zone  due  to  the  final  burning 
of  the  carbon.  If  sufficient  air  be  mixed  with  the  gas  before 
ignition,  as  in  a  Bunsen  burner,  or  if  air  be  blown  in  by  a  blow- 
pipe, a  more  intense  heat  is  obtained  all  through  the  flame.  The 
illuminating  and  soot-making  powers  then  disappear,  because  the 
carbon  burns  at  once  with  the  hydrogen  and  there  is  no  luminous 
cone  of  white-hot  carbon  atoms. 

Valence,  Atomicity,  Quantivalence.— When  two  substances 
have  acted  upon  each  other  and  caused  transformations,  they  are 
said  to  have  entered  into  reaction.1 

The  atomic  weights  of  the  elements  do  not  express  their  rel- 
ative values  in  the  mutual  reactions. 

In  the  equation  Zn  +  H2SO4  =  ZnSO4H-H2,  i  atom  of  zinc 
proves  its  equal  value  to  2  of  hydrogen  by  exchanging  for  the 
hydrogen  atoms,  taking  their  place.  The  zinc  is  accepted^by  the 
SO4  as  being  equal  in  chemical  power  to  the  2  hydrogen  atoms. 
In  the  same  way  i  atom  of  chlorin  is  substituted  for  i  atom  of 
hydrogen;  i  of  oxygen  for  2  of  hydrogen;  i  of  nitrogen  for  3 
of  hydrogen;  i  of  carbon  for  4  of  hydrogen;  i  of  phosphorus 
for  5  of  hydrogen;  and  i  atom  of  sulphur  for  as  many  as  6  atoms 
of  hydrogen.  This  value  of  a  combining  atom  compared  with 
that  of  an  atom  of  hydrogen  is  called  its  valence,  valency,  or  quan- 
tivalence.  If  its  valence  is  equal  to  one  of  hydrogen,  it  is  monovalenl 
or  univalent  and  is  termed  a  monad,  such  as  Cl,  Br,  I,  K,  Na,  Ag; 
one  of  double  value  is  divalent  or  bivalent  and  is  termed  a  dyad, 
as  O,  S,  Cu,  Hg,  Zn,  Ca;  one  of  triple  value  is  trivalent  and  called 
a  triad,  as  P,  As,  Sb,  Bi;  one  of  quadruple  value  is  tetravalent 
or  quadrivalent,  and  is  called  a  tetrad,  as  C,  Si,  Al,  Pt,  Pb;  one  of 
quintuple  value  is  pentavalent  or  quinquivalent,  called  a  pentad, 
as  P.;  one  of  sextuple  value  is  hexavalent  or  sexivalent,  and  called 
a  hexad,  as  S. 

The  cause  of  valence  has  not  been  determined,  though  a  recent 
speculation  concerning  it  may  prove  of  some  help.  The  work 
of  Faraday  embodied  in  his  laws  (p.  52)  showed  that  the  electric 
charge  of  an  ion  was  proportional  to  its  valence.  As  nearly  all 
chemical  action  is  between  charged  ions,  one  charge  may  stand 
for  univalence,  then  a  bivalent  ion  is  one  that  carries  two  charges, 
the  trivalent,  three,  and  so  on.  The  amounts  of  the  different  ions 
carrying  the  same  charge  are  in  the  proportion  of  the  atomic 
weights  of  the  ions.  To  set  free  a  bivalent  ion  requires  twice  as 
much  electricity  as  to  free  a  univalent  one  and  the  trivalent  thrice 

1  The  word  reaction  is  also  used  to  describe  the  effect  of  acids  and  bases  on  cer- 
tain colored  indicators,  such  as  litmus.  The  reaction  is  neutral  when  it  does  not 
alter  the  color  of  either  red  or  blue  litmus;  it  is  acid  when  it  turns  blue  litmus  red; 
alkaline  when  it  turns  red  litmus  blue. 


ATOMIC    THEORY  115 

and  so  on.  No  ion  has  more  than  eight  charges  (octivalent),  and 
none  has  less  than  one,  which  is  that  of  hydrogen.  Each  valence 
is  sometimes  referred  to  as  a  bond  or  link  of  attachment.  It  is 
sometimes  symbolized  by  radiating  strokes  and  sometimes  by 
accent  marks  and  Roman  numerals,  placed  above  and  to  the 
right  of  the  symbol  of  the  element,  thus: 

H-        H' 

-  O  -       O" 

V 

N          N"' 

I 

I 
-  C  -  Ov 


P  PV 

A 
V 
-  S  -       SVI 

A 

Variation  of  Valence.— The  valence  of  an  element  is  not  a 
fixed  and  unchanging  quantity;  thus,  nitrogen  in  nitrous  oxid,  N2O, 
is  a  monad;  in  ammonia,  NH3,  it  is  a  triad,  and  in  ammonium 
chlorid,  NH4C1,  it  is  a  pentad. 

In  view  of  the  fact  that  the  valence  of  an  element  may  vary 
with  the  temperature,  with  the  nature  of  the  other  substance,  and 
with  unknown  conditions,  it  cannot  be  considered  an  absolute 
endowment  of  the  atom,  but  only  as  a  statement  of  its  attractive 
power  in  the  special  class  of  compounds  being  studied. 

Graphic  Formulas. — In  another  place  (p.  no)  two  methods  of 
notation  were  used  for  one  substance.  These  were  called  the 
empiric  and  constitutional  formulas  of  ferric  hydroxid.  In  addi- 
tion to  these  methods  of  noting  the  results  of  discovery  chemists 
sometimes  fix  the  impression  they  have  received  as  to  the  internal 
arrangement  of  a  complex  molecule  by  a  graphic  formula.  When 
it  is  desired  to  show  that  the  iron  in  ferric  hydroxid  acts  as  a  triva- 
lent  atom,  and  that  the  hydroxyl  groups  are  monovalent,  the  following 
graphic  form  is  used: 

H 

I 

O 
I 
Ferric  hydroxid     .    .    Fe(OH)3  .    .      H-O-Fe-O-HL 


H6  NON-METALS 

Classification  of  the  Elements. — In  an  earlier  section  (p.  65) 
the  elements  to  be  studied  were  grouped  in  classes  for  emphasizing 
certain  important  properties.  That  arrangement,  while  serving  the 
purpose  at  that  point,  does  not  pretend  to  be  the  only  one  of  value. 
For  different  needs  there  are  different  lists,  more  or  less  special  or 
one-sided.  The  ordinary  table  is  alphabetic,  the  only  claim  made 
for  it  being  that  it  is  easy  for  reference. 

In  the  periodic  system  Mendelejeff  has  grouped  them  by  their 
valence,  and  the  elements  thus  allied  he  has  placed  in  the  order 
of  their  atomic  weights,  so  as  to  emphasize  the  significant  fact 
that  they  differ  from  each  other  by  approximately  a  multiple  of 
the  number  8.  It  has  been  shown  that  with  this  regular  numeric 
increase  in  atomic  weights  there  is  a  corresponding  progression 
of  properties,  thereby  raising  the  presumption  that  the  physical 
and  chemical  properties  oj  elements,  and  also  the  constitution  and 
properties  of  their  compounds  are  periodic  junctions  oj  the  atomic 
weights  (Mendelejeff s  periodic  law). 

When  the  atomic  weights  were  first  calculated  hydrogen  was 
taken  as  i,  and  oxygen  was  found  to  be  16.  As  nearly  all  the 
elements  unite  with  oxygen,  their  atomic  weights  were  calculated 
on  the  basis  of  O  =  i6,  and  these  weights  have  been  in  use  many 
years.  It  has  been  discovered,  however,  that  there  was  a  mistake, 
and  that  if  O  =  i6,  then  H  is  not  i,  but  1.008.  The  whole  ques- 
tion is  simply  one  of  convenience,  and  as  the  table  based  on  O  =  16 
is  adjudged  best  by  some  of  the  most  authoritative  chemical 
societies,  it  is  the  one  used  in  the  present  work.  For  the  purpose  of 
simplifying  study  in  the  body  of  this  work,  the  nearest  integer  is 
used,  the  fractions  being  ignored. 

The  table  that  follows  on  pp.  117  and  118  is  not  Mendelejeff's, 
though  it  is  based  upon  the  periodic  system.  In  perpendicular 
columns  similar  elements  are  grouped  in  sections  by  their  numeric 
values. 

In  the  section  where  the  valence  is  marked  o  will  be  found  the 
argon  family  of  atmospheric  elements,  which  are  unable  to  unite 
with  other  elements.  In  the  next  section,  marked  I.,  are  hydrogen 
and  the  alkali  metals.  In  the  next,  marked  II.,  are  the  divalent 
alkaline  earth  metals  and  the  heavy  metals  of  the  zinc  family.  The 
section  marked  III.  contains  trivalent  boron,  the  earth  metals,  and 
the  corresponding  heavy  metals,  gallium  and  indium.  Section  IV. 
contains  two  tetravalent  non-metals  and  metals  of  the  titanium 
family,  along  with  those  of  the  tin  family.  Section  V.  contains 
elements  that  are  pentavalent  or  trivalent,  such  as  the  nitrogen 
family.  In  Section  VI.  are  elements  that  are  divalent  or  hex- 
avalent.  In  Section  VII.  are  the  halogens,  which  are  univalent 
or  heptavalent,  and  three  metals  that  are  divalent  on  the  one  hand 


ATOMIC    THEORY 


117 


or  heptavalent  on  the  other.  In  the  last  section  are  the  metals 
which  cannot  be  placed  in  any  previous  class — the  iron  and  the 
platinum  families. 

Elements  Arranged  in  Arithmetic  Progression  according  to  Atomic 
Weight  and  Valence 


NAME. 

DERIVATION. 

2 

>. 

C/3 

1-a 
II 

O  =  i6 

^  Atomic 
II  Weight. 

H 

Valence. 

He 

4.00 

4.000 

o 

Ne 

20  oo 

ig.gOO 

o 

Gr.,  without  energy  .  . 

A 

•30.00 

39.600 

Krypton  

Gr.,  hidden  

Kr 

81.80 

8l.2OO 

o 

Xenon  

Gr.,  stranger  

X 

128.00 

127.000 

Hydrogen  .... 
Lithium  

Gr.,  water-forming  
Gr.  lithos,  stone  

H 

Li 

Na 

I.  01 

7.03 

I.OX) 

6.970 

22  880 

I. 
I. 
I 

Potassium  (kali-  \ 

Eng.  potash  

K 

38.820 

I 

urn)  j 
Rubidium  .... 
Cesium    ...... 

L.  rubidus,  red  (its  spectrum)  , 
L.  caesius,  sky-blue  " 

Rb 
Cs 

85-50 
132.90 

84-750 
131.900 

L 

Glucinum              1 

Gr.  glykys,  sweet  

Gl 

II 

(beryllium)    .  j 
Magnesium    .    .    . 
Calcium  
Zinc 

Magnesia,  district  in  Thessaly  . 
L.  calx,  lime  
Ger.  zink  .  . 

S 

Zn 

24.30 

40.00 

24.IOO 

39.800 

II. 
II. 
H 

Strontium  .... 
Cadmium    .... 

Strontian,  a  town  in  Scotland  . 
Gr.  cadmeia,  calamine  .... 

Sr 
Cd 
Ba 

87.60 

112.  2O 

86.950 
HI.550 

II. 
II. 
II 

Hg 

I    or  II 

Radium    .    . 

Rd 

II 

B 

III 

Aluminum  .... 

L.  alumen,  alum  .  . 

Al 

III 

Scandium 

Sc 

III 

Gallium  
Yttrium  
Indium    
Lanthanum    .    .    . 
Neodymium  .    .    . 
Praseodymium  .    . 
Samarium  .... 
Gadolinium    .    .    . 
Terbium  
Erbium    
Thulium     .... 

L.  Gallia,  France  
Ytterby,  a  town  in  Sweden  .  .  . 
From  its  indigo  spectrum  .  .  . 
Gr.  lanthano,  conceal  
Gr.  neo,  new,  and  didymos,  twin 
Gr.  praeseo,  green,  and  didymos 
Samarski,  a  Russian  savant  .  . 
Gadolin,  a  Russian  chemist  .  . 
Ytterby,  a  town  in  Sweden  .  .  . 
Ytterby,  a  town  in  Sweden  .  .  . 
Thule,  Northland  

Ga 
Yt 
In 
La 
Nd 
Pr 
Sm 
Gd 
Tb 
Er 
Tu 

69.00 
89.10 
113.70 

138.80 
I40-SO 

I43-5o 
150.00 
156.10 
160.00 
166.30 
170  70 

69.500 
88.300 
II3.IOO 
137.600 
142.500 
139.400 
I49.2OO 
155.800 
158.800 
164.700 

III. 
III. 
III. 
III. 
III.  or  IV. 
III.  or  IV. 
III. 
III. 
III. 
III. 
Ill 

Ytterbium  .... 
Thallium    .... 

Ytterby,  a  town  in  Sweden  .  .  . 
Gr.  thallos,  budding  twig  ; 

Yb 
Tl 

i73-oo 
204.18 

171.900 
2O2.6lO 

III. 
I.  or  III. 

Carbon    
Silicon  

L.  carbo,  charcoal  
L.  silex,  flint  .  .  . 

C 

Si 

12.  OO 

28  40 

II.9OO 
28  2OO 

IV. 

II     III    or  IV 

Titanium    .... 
Germanium    .    .    . 
Zirconium  .... 
Tin  (stannum) 
Cerium    .    . 

L.  Titanes,  sons  of  the  earth  .  . 
L.  Germania,  Germany  .... 
Ar.  zarkun,  gold-colored  .  .  . 
Anglo-Saxon  
Planet  Ceres 

Ti 
Ge 
Zr 
Sn 
Ce 

48.00 
72.30 
90.60 
Iig.OO 

47.800 
71.900 
89.700 

IlS.lOO 

IV. 
II.  or  IV. 
IV. 
II.  or  IV. 
Ill    or  IV 

Lead  (plumbum) 

Anglo-Saxon 

Pb 

II   or  IV 

Thorium     .... 

God  Thor 

Th 

III    or  IV 

3    * 

3         ' 

Nitrogen     .    ,    .    . 
Phosphorus   .    .    . 

Gr.,  niter-forming  
Gr.,  light-bearing  

N 
P 

14.03 

I3-930 

III.  or  V. 
Ill    orV 

Vanadium  .... 
Arsenic    
Columbium           \ 

Goddess  Vanadis  (Freya)  .  .  . 
L.  arsenicum  

Columbia 

V 
As 

Cb 

51.40 
75.00 

51.000 
74-450 

II.,  III.  or  IV. 
III.  or  V. 

Ill   or  V 

Antimony      (sti-  \ 
bium)   .    .    .    .  / 
Tantalum  .... 
Bismuth  .   . 

L.  antimonium  

Tantalus  (Gr.  myth.)  
Ger.  (  unknown  orie-in^.  . 

Sb 

Ta 
Ri 

I2O.OO 
l82.6o 

119.500 
181.500 

III.  or  V. 

V. 
TTT    nr  V 

n8 


NON-METALS 


Elements  Arranged,  in  Arithmetic  Progression  according  to  Atomic 
Weight  and  Valence — Continued 


NAME. 

DERIVATION. 

I 

°if 

c  '£ 

Valence. 

0=i6 

H  =  i 

Oxygen  
Sulfur  (Sulphur)    . 
Chromium  .... 

Gr.,  acid-forming    
L.  sulphur   
Gr.  chroma,  color  

0 

s 

Cr 

16.00 
32.06 
52.10 

15.880 
31.830 
51.700 

II.  or  VI. 
II.  or  VI. 
II.  or  III. 

Selenium     .... 

Gr.  selene,  moon    

Se 

79.00 

78.600 

II.  or  VI. 

Molybdenum     .    . 
Tellurium  ... 

Gr.  molybdos,  lead         
L.  tellus,  earth    

Mo 
Te 

96.00 
127.00 

95.300 
126.500 

II.,  III.,  IV.  orV. 
II.  or  VI. 

Tungsten    (wol-  ) 

Swed     heavy  stone   

W 

184.00 

182  600 

II     IV     V   or  VI 

framium)  .    .  j 

Uranium     .... 

Planet  Uranus    

U 

238.60 

237.800 

III.  ,  IV.,  V.,  VIII. 

Fluorin    

~L.Jluor,  <.fiuo,  flow    

F 

19.00 

18.900 

I.  or  VII. 

Chlorin    

Gr.  chloros,  green  

Cl 

35-45 

75  180 

I.  or  VII. 

Manganese        .    . 

L.  magnes   magnet 

Mn 

55  °° 

II.,  III.  or  IV. 

Bromin    

Gr.  brontos,  stench    ...... 

Br 

79-95 

79.340 

I.  or  VII. 

Ruthenium    .    .    . 

Rus.  Ruthenia    

Ru 

IOI.OO 

100.900 

II.,  III.  or  IV. 

lodin    

Gr.  iodes,  violet  

I 

126.85 

125.890 

I.  or  VII. 

Osmium  

Gr.  osme,  odor     . 

Os 

189  600 

II.  or  IV 

Iron  (ferrum)  . 

Anglo-Saxon,  iren  . 

Fe 

55.860 

II    or  III. 

Nickel.   ..... 
Cobalt  

Ger.  kupfernickel  
Ger.  kobold,  goblin    .    .        .    . 

Ni 
Co 

58.00 

58-250 

II.  or  III. 
II.  or  III. 

Copper 

Cu 

63  60 

I    or  II 

Rhodium    .    . 

Gr.  rhodon,  rose     

Rh 

III. 

Palladium  .    . 

Planet  Pallas  .    .    

Pd 

106.60 

106.200 

II.  or  IV. 

Silver  (argentutn) 
Iridium    

Anglo-Saxon  seolfor  
L.  iris,  a  rainbow  

Irg 

107.90 
193,10 

107.110 
191.700 

I. 
II.,  III.  or  IV. 

Platinum    .... 

f  Span,  platina,  dim.  of  plata,  \ 

Pt 

195.00 

I93-400 

II.  or  IV. 

Gold  (auruin)  .   . 

Anglo-Saxon    

Au 

I.  or  III. 

CHLORIN    (Chloi-um) 

Symbol,  Cl.     Atomic  weight,  35.45. 

This  element  occurs  in  nature  chiefly  in  common  salt  (sodium 
chlorid),  of  which  it  constitutes  more  than  one-half  by  weight. 

Preparation. — Chlorin  is  prepared  on  a  large  scale  by  elec- 
trolysis of  a  solution  of  potassium  or  sodium  chlorid.  Chlorin 
separates  at  the  anode  and  hydrogen  at  the  cathode;  the  sodium 
as  hydroxid  remains  in  solution. 

NaCl      +      H,O      =      NaHO      +      H      +      Cl. 


Sodium  chlorid. 


Sodium  hydroxid. 


For  experimental  purposes  chlorin  is  prepared  from  sodium 
chlorid  by  first  displacing  the  sodium  with  hydrogen  to  make 
hydrogen  chlorid  (hydrochloric  acid),  and  then,  by  means  of  the 
oxygen  of  manganese  dioxid,  abstracting  the  hydrogen  to  form 
water.  The  first  step  is  taken  by  the  action  of  sulphuric  acid: 


(i)          2NaCl 

Sodium  chlorid. 


H2SO4 

Acid  sulphuric. 


Na2SO4 

Sodium  sulphate. 


2HC1 

Hydrogen  chlorid. 


CHLORIN 


In  the  second  stage  the  HC1  is  broken  up  by  the  rich  supply 
of  oxygen  in  the  manganese  salt: 

(2)        4HC1     +     MnO2      =      MnCl2    +     2H2O     +     C12. 

Manganese  dioxid.     Manganese  chlorid. 

A  better  method  is  to  perform  both  stages  at  once  by  heating 
in  a  flask  over  a  sand-bath  a  mixture  of  sodium  chlorid  and  gran- 
ular manganese  dioxid,  5  parts  of  each,  with  12  parts  of  sulphuric 
acid  and  6  parts  of  water  previously  mixed  and  cooled.  The  gas 
is  collected  in  glass-stoppered  bottles  by  downward  displacement. 
In  this  reaction  all  the  chlorin  present  is  evolved,  since  the  man- 
ganese is  taken  up  by  the  sulphuric  acid.  From  bleaching  powder 
(calx  chlorinata)  a  copious  supply  is  obtainable  without  heat  by 
the  action  of  hydrochloric  acid. 


Ca(ClO)Cl 

Calx  chlorinata. 


2HC1  CaCl 


H2O 


C1. 


Calcium  chlorid. 

Any  flask  or  wide-mouthed  bottle  will  serve  the  purpose  as  a 
generator.  It  should  be  closed  with  a  double-perforated  stopper. 
Through  one  hole  passes  a  dropping-funnel  with  stop-cock; 


FIG.  37. — Chlorin  evolved  from  calx  chlorata  washed  in  water  and  dried  in  sulphuric  acid. 

out  of  the  other  passes  the  delivery  tube,  which  may  enter  a 
wash-bottle  of  water  to  get  free  from  the  hydrochloric  acid  fumes 
and  another  of  sulphuric  acid  for  drying;  or,  if  absolute  purity  is 
not  required,  the  gas  may  pass  directly  into  the  collecting  jar. 
Being  nearly  two  and  a  half  times  heavier  than  air,  its  density 
enables  us  to  collect  it  in  dry  bottles  by  downward  displacement. 


I2Q  NON-METALS 

When  the  bottle-contents  are  greenish  yellow  throughout,  it  should 
be  closed  with  a  ground-glass  stopper  smeared  with  vaselin.  Its 
solubility  in  water  precludes  the  use  of  the  pneumatic  trough  unless 
the  water  be  warmed.  Even  the  mercury  trough  is  forbidden, 
because  it  combines  with  the  mercury. 

Physical  Properties. — Chlorin  is  a  gas  of  a  greenish-yellow 
color,  having  an  unpleasant,  irritating  odor  even  when  diluted  with 
air.  On  inhaling,  a  sense  of  suffocation  is  felt  in  the  chest  and  an 
irritation  in  the  nose  and  throat,  due  to  the  corrosive  action  of  the 
gas  on  the  lining  of  the  air-passages.  Its  specific  gravity  is  2.5. 
By  cold  [  —  34°  C.  (  —  29.2°  F.)]  and  pressure  it  is  converted  into 
a  greenish-yellow,  oily  liquid;  and  at  still  lower  temperatures, 
—  102°  C.  (—152°  F.),  it  solidifies  in  greenish-yellow  crystals. 

Liquor  Chlori  Compositus,  U.  S.  P. — Chlorin  Water. — This 
is  a  solution  of  0.4  per  cent,  of  chlorin  with  potassium  chlorid 
and  chlorin  oxid.  It  is  freshly  made  when  wanted  in  a  2-liter 
flask,  by  warming  for  three  minutes  potassium  chlorate,  5  gm., 
in  hydrochloric  acid,  18  c.c.,  diluted  with  an  equal  amount  of 
water  and  adding  water  to  dissolve  the  greenish  gas  evolved. 

2KC1O3    +    4HC1    =    C12    +    C12O4    +    2KC1    +    2H2O. 

Potassium  Hydrochloric  Chloric 

chlorate.  acid.  oxid. 

One  liter  of  water  under  ordinary  circumstances  will  absorb 
nearly  three  liters  of  chlorin,  becoming  the  reagent  chlorin-ivater. 
This  solution  has  the  color,  smell,  taste,  and  chemical  and  thera- 
peutic properties  of  the  gas  itself,  but  in  a  more  manageable  form. 
It  should  be  protected  from  light  by  keeping  in  dark  amber-colored 
bottles,  otherwise  a  decomposition  will  occur. 

In  direct  sunlight  chlorin  quickly  abstracts  hydrogen  from  the 
water  to  form  hydrochloric  acid,  oxygen  being  set  free. 

H2O      +      2C1      =      2HC1     +      O. 

This  belongs  to  the  class  of  photochemical  effects,  such  as 
are  seen  in  the  processes  of  photography  and  the  assimilation  of 
carbon  dioxid  by  green  plants  in  the  sunlight.  The  chemical 
powers  reside  chiefly  in  the  blue  and  violet  rays,  which  are  shut 
out  by  reddish  glass. 

Chemical  Properties.— Chlorin  has  an  atomic  weight  35.45. 
Like  oxygen  it  does  not  burn,  but  at  ordinary  temperatures  dis- 
plays greater  activity  in  supporting  combustion  than  does  oxygen. 
The  velocity  of  its  reactions  produces  sufficient  heat  for  combustion, 
even  when  it  unites  spontaneously  with  other  substances.  Im- 
mersed in  it,  phosphorus  takes  fire  without  previous  heating, 
powdered  antimony  forms  a  rain  of  sparks,  and  a  warmed  ball 


HYDROGEN    CHLORID  121 

of  dutch-metal  foil  becomes  incandescent.1  Moist  chlorin  com- 
bines directly  at  room-temperature  with  all  metals  except  iridium, 
and  with  most  of  the  non-metals.  In  all  the  cases  of  union  above 
mentioned  the  compound  is  a  chlorid  of  the  other  element. 

Toxicology. — Symptoms. — When  inhaled  in  small  amounts 
chlorin  causes  a  suffocative  feeling  and  cough.  If  taken  undi- 
luted it  causes  difficult  breathing,  a  painful  sense  of  tightness  in 
the  chest,  and  violent  cough  with  hemorrhage.  Indirectly  the 
nerve-centers  are  involved,  producing  stupor  and  even  heart  failure. 

Fatal  Dose. — Fatal  consequences  are  not  apt  to  occur  unless 
the  subject  is  in  delicate  health,  and  the  gas  is  taken  with  little 
admixture  of  air. 

Treatment. — Fresh  air  must  be  given  at  once,  and  the  pain 
relieved  by  the  inhalation  of  ether.  The  symptoms  of  acute 
bronchitis,  narcotism,  and  enfeebled  heart  action  must  be  treated 
by  appropriate  remedies. 

Detection. — The  gas  can  be  recognized  by  its  odor  and  its 
bleaching  action  on  moist  litmus-paper.  As  chlorin-water  it  has 
the  same  properties,  and  in  addition  dissolves  gold-foil. 

Direct  Union  of  Chlorin  and  Hydrogen.— The  intense  attrac- 
tion that  exists  between  hydrogen  and  chlorin  is  shown  in  many 
ways.  If  the  two  gases  be  mixed  in  equal  proportions  and  the  vessel 
placed  in  direct  sunlight,  a  violent  explosion  occurs;  if  the  mixture 
be  kept  out  of  strong  light,  the  union  likewise  takes  place,  but  quietly 
and  slowly.  After  the  union  the  green  color  is  absent,  and  if  the 
vessel  be  opened  under  water  that  liquid  rises  quickly  in  the  bottle 
and  acquires  the  sour  taste  and  acid  reaction  of  hydrochloric  acid. 

An  ignited  jet  of  hydrogen  continues  to  burn  when  introduced 
into  a  vessel  containing  chlorin,  the  flame  changing  from  blue  to 
whitish  green.  If  the  vessel  be  afterward  rinsed  out  with  water 
the  water  will  taste  sour  and  redden  blue  litmus,  showing  the 
formation  of  hydrochloric  acid. 

Indirect  Union  of  Chlorin  and  Hydrogen.— There  are  many 
compounds  of  hydrogen  with  carbon  that  lose  their  hydrogen  in  the 
presence  of  chlorin.  A  paraffin  taper  ignited  will  continue  to  burn 
at  the  mouth  of  a  jar  containing  chlorin,  but  the  carbon  separates 
in  dense  clouds  of  soot. 

CH4     +      C14     =     4HC1     +      C. 

Hydrocarbon. 

Uses  in  the  Arts. — Although  absolutely  dry  chlorin  does  not 
bleach,  the  moist  vapor  as  a  bleaching  agent  takes  high  rank. 
The  native  vegetable  fibers  are  not  white,  and  to  make  them 
acceptable  to  the  eye  linen,  cotton,  and  paper  must  be  bleached. 

1  In  its  wider  sense  combustion  is  any  chemical  process  evolving  a  temperature 
of  incandescence  or  500°  C.  (932°  F.). 


122  NON-METALS 

A  convenient  source  of  chlorin  is  the  bleaching  powder  of  com- 
merce, to  be  described  later.  Most  color  principles  contain  hydro- 
gen, which  is  partly  directly  removed  by  the  chlorin,  but  in  the 
presence  of  water  the  action  is  much  more  decided.  By  decom- 
posing the  water  chlorin  sets  free  active  nascent  oxygen,  thus 
becoming  an  oxidizing  agent.  This  oxygen  instantly  converts 
sulphurous  acid  into  sulphuric  acid,  a  higher  oxygen  compound: 

H2S03      +     C12      +     H20  H2S04     +     2HC1 

Acid  sulphurous.  Acid  sulphuric.     Acid  hydrochloric. 

Chlorin  discharges  the  color  of  common  anilin  inks,  but  does 
not  affect  the  carbon  of  printer's  ink  or  india  ink.  This  can  be 
shown  by  blotting  a  printed  page  with  common  ink  and  dipping 
it  into  chlorin  water,  when  the  printed  letters  reappear  as  the 
writing  ink  fades  away. 

As  a  deodorizer,  chlorin  breaks  up  the  foul-smelling  gases  of 
putrefaction,  hydrogen  sulphid  (H2S)  and  ammonia  (NH3),  by 
abstracting  the  hydrogen  and  oxidizing  the  sulphur  and  nitrogen. 

As  a  disinfectant,  chlorin  poisons  the  bacteria  that  produce  the 
infectious  diseases.  To  do  this  it  must  be  in  solution,  as  the  gas 
is  not  effectual  in  killing  them  or  in  materially  lessening  their 
activity.  Some  of  the  best  bactericides  are  compounds  of  chlorin 
or  its  associate,  iodin. 

Hydrogen  Chlorid  (HC1)  (Hydrochloric  Acid  Gas).— It  has 
been  stated  above  that  this  compound  can  be  formed  by  the 
direct  union  of  its  elements,  but  for  laboratory  purposes  it  is 
more  conveniently  prepared  by  the  action  of  sulphuric  acid  on 
common  salt  (p.  135);  gentle  heat  is  required  to  disengage  the  gas 
HC1,  leaving  sodium  sulphate  in  solution. 

The  gas  can  be  prepared  without  heat  by  removing  water  from 
commercial  hydrochloric  acid.  Using  an  apparatus  like  the 
generating  flask,  Fig.  37,  nothing  but  concentrated  sulphuric  acid 
is  placed  in  the  flask.  Gradually  the  hydrochloric  acid  is  dropped 
in  through  the  tap-funnel.  A  colorless  gas  is  evolved  which  is 
a  little  heavier  than  the  air  (specific  gravity  1.247),  and  by  cold 
and  pressure  becomes  first  a  liquid,  and  at  —113°  C.  (—173°  F.) 
becomes  a  solid.  Having  collected  some  of  the  gas  in  an  inverted 
test-tube  over  a  mercury  trough,  a  few  cubic  centimeters  of  water 
may  be  blown  through  a  bent  pipet  so  as  to  rise  through  the  mer- 
cury and  make  a  top  layer  about  i  inch  deep.  The  mercury  now 
ascends,  thus  showing  that  the  gas  has  been  absorbed  by  the  water. 
If  the  water  were  colored  blue  by  litmus,  it  is  turned  red,  and 
a  piece  of  magnesium  allowed  to  float  up  to  the  surface  of  the  mer- 
cury, causes  effervescence  of  hydrogen  and  fall  of  the  mercury, 
thus  showing  that  hydrochloric  acid  has  been  formed.  The 


ACIDS,    BASES,   AND    SALTS  123 

volume  of  hydrogen  evolved  equals  half  that  of  the  original  hydro- 
gen chlorid.  By  raising  the  tube  out  of  the  mercury,  air  enters  to 
form  an  explosive  mixture  with  the  hydrogen. 

ACIDS,  BASES,  AND  SALTS 

Solubility  of  Hydrogen  Chlorid.— One  of  the  most  remark- 
able properties  of  hydrogen  chlorid  is  its  solubility  in  water. 
At  ordinary  temperatures  450  volumes  will  dissolve  in  i  volume 
of  water,  evolving  a  large  amount  of  heat.  The  heat  is  an  indica- 
tion of  a  special  process  different  from  simple  solution.  The 
volumes  of  most  gases  absorbed  by  water  are  not  nearly  so  great 
as  450.  Henry's  law  for  the  absorptive  property  of  water  for 
gases  is  that  the  amount  absorbed  is  proportional  to  the  pressure 
(p.  91).  In  the  case  of  the  absorption  of  hydrogen  chlorid  the 
effect  of  pressure  is  discernible  only  to  a  slight  degree.  These 
facts  make  it  appear  that  the  atoms  of  hydrogen  chlorid  in  solution 
are  no  longer  coupled  as  in  their  former  condition  of  a  dry  molecule. 
Other  evidence  of  a  conversion  is  seen  in  the  fact  that  pure  anhy- 
drous hydrogen  chlorid  compressed  to  a  liquid  has  no  acid  proper- 
ties. To  develop  these  some  new  relation  of  its  atoms  is  needed, 
and  this  change  is  brought  about  by  the  solution  in  water.  This 
molecular  change  is  explained  in  the  following  way:  When  the 
gas  dissolves  only  a  part  remains  as  unchanged  molecules,  and 
hence  subject  to  Henry's  law.  Another  part  is  thrown  into  a 
different  condition  and,  therefore,  acquires  new  properties  (p.  131). 

Further  confirmation  of  this  view  is  shown  in  the  fact  that  the 
highly  volatile  hydrogen  chlorid  in  dilute  solution  does  not  lower 
the  boiling-point  of  water,  but  raises  it.  This,  too,  is  an  exception 
to  the  rule  for  aqueous  solutions  of  volatile  substances,  which 
usually  have  an  opposite  effect.  These  peculiarities  in  hydrogen 
chlorid  are  best  explained  by  the  theory  of  an  abnormality  in  the 
condition  and  number  of  the  ultimate  particles  when  they  are 
dissolved  in  water.  Solution  has  apparently  increased  the  num- 
ber of  particles,  which  could  only  be  done  by  some  sort  of  dis- 
sociation of  the  constituent  hydrogen  and  chlorin  in  the  molecules 
of  hydrogen  chlorid. 

Acids. — In  calling  the  aqueous  solution  of  hydrogen  chlorid 
an  acid  we  attribute  to  it  certain  properties  common  to  a  large 
class.  The  word  is  derived  from  acies,  sharp,  and  originally 
described  the  taste  only.  It  was  discovered  afterward  that  all 
substances  which  have  this  taste  possess  a  common  effect  upon 
the  blue  dye,  litmus,  turning  it  red  (PL  5,  Fig.  i);  and  further, 
that  in  the  presence  of  metallic  zinc  or  magnesium  they  yield 
hydrogen.  Powdered  magnesium  will  cause  effervescence  of 
the  inflammable  gas,  not  only  from  hydrochloric  acid,  but  also 


124 


NON-METALS 


from  any  acid  liquid,  even  the  juice  of  subacid  fruits.  While 
hydrogen  may  be  regarded  as  the  element  giving  the  acid  its  powers, 
we  must  not  lose  sight  of  the  fact  that  it  does  not  always  carry  this 
acid  endowment  with  it.  If  it  did,  then  water  and  the  neutral 
compounds,  alcohol,  the  paraffins,  and  fats,  would  be  acid. 

The  hydrogen  constituent  is  shown  in  formulas  of  the  follow- 
ing strong  acids:  hydrochloric,  HC1;  sulphuric,  H2SO4;  nitric, 
HNO3;  phosphoric,  H3PO4. 

Bases. — An  acid  that  tastes  sour,  reddens  litmus,  and  takes 
a  metal  in  place  of  hydrogen,  loses  all  these  properties  by  the 
addition  of  sodium  hydroxid  (caustic  soda).  The  change  in  the 
color  of  acid-red  litmus  to  blue  is  so  sharply  defined  that  it  is 
customary  to  depend  on  that  alone  as  an  indicator  of  the  simul- 
taneous loss  of  all  acid  properties.  If  the  acid  be  hydrochloric 
and  litmus-paper  have  been  used,  on  evaporation  there  is  left  in 
the  dish  a  white  crystalline  compound  which  tastes  neither  sour 
nor  alkaline,  but  salty.  It  is  easily  identified  as  kitchen  salt, 
sodium  chlorid,  and  is  produced  according  to  this  reaction: 
HC1  +  NaHO  Nad  +  H2O. 

Sodium  hydroxid.  Common  salt. 

Neutralization. — The  process  just  described  of  neutralizing 
the  acid  properties  and  forming  water  and  a  salt  can  be  performed 
by  any  one  of  a  large  class  of  substances  known  as  bases.  They 
are  compounds  of  metals  with  hydroxyl  (HO),  and  are  said  to  be 
basic  because  they  constitute  the  solid  residue  when  the  more 
volatile  acid  constituent  of  the  salt  is  driven  off  by  heat.  The 
soluble  bases,  of  which  the  caustic  alkalies,  soda,  potash,  and 
ammonia,  are  the  most  marked  representatives,  are  characterized 
by  their  opposition  to  the  acids  in  restoring  blue  litmus,  and  in 
overcoming  their  acid  taste  and  hydrogen-generating  property. 
This  accomplished,  we  have  products  that  are  neutral,  such  as 
water  and  common  salt.  In  brief:  acids  and  bases  have  the  power 
oj  destroying  the  properties  of  each  other. 

Definite  Weights  Engaged. — In  forming  a  salt,  water  is  also  a 
necessary  product,  because  the  hydroxyl  (HO)  of  the  base  attracts 
the  hydrogen  just  liberated  from  the  acid.  The  numeric  expres- 
sion of  this  affinity  is  that  the  molecular  weight,  17  gin.,  of  hy- 
droxyl in  the  base  is  required  to  hold  the  atomic  weight,  i  gm.,  of 
hydrogen.  Until  this  element  is  thus  held  the  acid  properties  persist. 

Acidimetry. — By  using  a  solution  of  sodium  hydroxid  or 
potassium  hydroxid  of  known  strength  we  have  a  standard  of 
hydrogen-fixing  power,  and  units  of  it  will  be  equivalent  to  definite 
amounts  of  acid  in  the  solution  neutralized.  To  make  the  two 
solutions  of  reciprocal  strength  and  their  neutralizing  power 
equivalent  to  i  gm.  of  hydrogen,  they  should  be  accurately  tested 


ACIDS,    BASES,   AND   SALTS  125 

in  advance.  The  standard  adopted  is  the  normal  solution,  (N), 
for  which  the  acid  is  weighed  in  a  sufficient  number  of  grams  to 
contain  i  gm.  of  acid  hydrogen,  and  then  dissolved  in  sufficient 
volume  of  water  to  make  i  liter  of  the  finished  product.  Such 
a  solution  is  sometimes  called  a  gram-atom,  to  imply  that  there  is 
in  it  the  atomic  weight  of  hydrogen,  i,  in  grams.  Oxalic  acid, 
being  a  crystalline  solid  of  constant  composition  and  easily  weighed, 
is  chosen  for  the  acid  reagent.  Its  formula  is  H2C2O4.2H2O,  with 
a  molecular  weight  of  125.7.  As  there  are  2  atoms  of  acid  hydro- 
gen counted  to  make  125.7,  the  amount  representing  i  atom  of 
hydrogen  would  be  one-half  or  62.85.  Then  62.85  gm-  *n  water,  to 
make  1000  c.c.,  is  called  the  normal  solution.  If  we  want  tc  repre- 
sent weak  acidity,  like  that  of  the  urine  and  gastric  juice,  one-tenth 
of  62.85  or  6.28  gm.  per  1000  c.c.  of  solution  is  used,  making  the 

/N\ 
decinormal  I  —  \solution  of  oxalic  acid,  each  cubic  centimeter  of  which 


contains  0.00628  gm.  of  oxalic  acid  capable  of  neutralizing  0.0056 
gm.  of  potassium  hydroxid  or  0.004  gm-  of  sodium  hydroxid.  The 
basic  or  alkaline  solution  must  contain  the  molecular  weight  in 
grams  or  the  exact  quantity  of  potassium  hydroxid  (56  gm.)  or 
sodium  hydroxid  (40  gm.)  necessary  to  hold  the  i  gm.  of  hydrogen 
that  would  be  taken  from  the  normal  acid  solution. 

As  the  caustic  alkalies  contain  varying  amounts  of  water  they 
should  first  be  standardized  by  testing  their  concentration  with 
the  corresponding  solution  of  oxalic  acid.  Thus:  an  excess,  say 
60  gm.  of  potassium  hydroxid  or  50  gm.  of  sodium  hydroxid,  is 
dissolved  in  900  c.c.  of  water  and  tested  against  10  c.c.  of  normal 
oxalic  acid  solution  placed  in  a  beaker  and  reddened  with  litmus 
to  ascertain  the  amount  of  alkali  necessary  to  neutralize  it.  This 
amount  multipled  by  100  gives  the  number  of  cubic  centimeters  of 
alkaline  solution  containing  the  molecular  weights — 56  gm.  potas- 
sium hydroxid  or  40  gm.  of  sodium  hydroxid.  If  the  amount  be 
9.5,  then  950  c.c.  will  contain  the  gram-molecule  amounts  of  alkali, 
and  50  c.c.  of  water  (enough  to  make  1000  c.c.)  must  be  added.1 

Equivalents  of  Acids  and  Alkalies. — The  label  of  the  bottle 
containing  the  normal  solutions  may  then  state  that  i  c.c.  of  the 
contents  (NaHO  or  KHO)  is  the  equivalent  of— 

Hydrochloric  acid,  HC1 0.03637  gm. 

Nitric  acid,  HNO3 0.06289    «« 

Sulphuric  acid,  H2SO4 0.04891     " 

Oxalic  acid,  H2C2O4.2H2O 0.06285    " 

1  The  decinormal  solution  for  urine  testing  can  be  made  by  placing  100  c.c.  of 
the  solution  just  described  in  a  mixing  bottle  and  adding  900  c.c.  of  water.  Or  the 
whole  operation  can  be  changed  by  dividing  the  weights  named  above  by  10,  so  that 
at  last  we  have  5.6  gm.  of  potassium  hydroxid,  or  4  gm.  of  sodium  hydroxid,  in  1000 
c.c.  of  water  (pp.  550,  584) 


126 


NON-METALS 


The  label  of  the  normal  oxalic  acid  solution   may  state  that 
i  c.c.  of  the  contents  is  equivalent  to — 

Ammonia,  NH3 0.01701  gm. 

Sodium  hydroxid,  NaHO , 0.040        " 

Potassium  hydroxid,  KHO 0.056 

Volumetric  Analysis. — If  it  be  desired  to  determine  the 
percentage  of  hydrogen  chlorid  dissolved  in  a  sample  of  hydro- 
chloric acid,  3.65  gm.  of  the  sample  are  weighed,  put  into  the 
beaker,  and  tested  by  adding  normal  solution 
of  potassium  hydroxid  to  neutralization.  If  it 
require  10  c.c.  of  KHO,  then  the  acid  liquid 
is  a  10  per  cent,  solution,  HC1  (the  acidum  hy- 
drochloricum  dttutum.—U.  S.  P.)-  If  only  9  c.c. 
sufficed,  then  the  sample  was  9  per  cent.  HC1, 
and  is  not  concentrated  to  the  official  standard. 
Volumetric  analysis  is  performed  very  rapidly, 
and  in  most  cases  the  result  is  more  accurate 
than  if  obtained  by  the  tedious  operation  of 
precipitation,  filtration,  drying,  and  weighing 
known  as  the  gravimetric  method.  Unless  the 
chemist  has  had  much  experience 
he  will  obtain  more  accurate  re- 
sults by  measuring  quantities  with 
a  buret  than  by  weighing  them  on 
a  balance.  This  operation  of 
measuring  by  volumetric  analysis 
is  called  titration,  from  the  French 
word  litre,  referring  to  the  special 
label  stating  the  standard  strength 
of^solution  and  its  equivalents. 

Besides  the  reciprocal  determi- 
nation of  acids  and  alkalies,  the 
other  principal  volumetric  opera- 
tions are  oxidation  and  reduction 
(using  permanganate  for  oxidiz- 
ing and  oxalic  acid  for  reducing); 
precipitation  (chlorids  by  silver 
nitrate);  and  iodimetry  (reaction  of  iodin  and  hyposulphite). 
Method  of  Titration. — A  definite  amount  of  the  substance  .to 
be  examined  is  measured  off  in  a  graduated  pipet  (Fig.  38)  and 
placed  in  a  small  beaker  or  porcelain  capsule.  A  few  drops  of 
the  color  indicator  is  then  added,  so  that  the  point  of  neutraliza- 
tion or  end  of  the  reaction  can  be  accurately  determined.  Litmus 
has  been  mentioned  as  an  indicator,  but  phenolphthalein  (i  per 
cent,  in  dilute  alcohol)  is  very  sensitive,  and  may  be  used  when 


: 


FIG.  38. — Pipet  for 
measuring. 


FIG.  39. — Mohr's 
burets. 


DISSOCIATION  127 

neither  ammonia  nor  bicarbonates  are  titrated.  It  is  colorless  in 
acid  fluids,  but  reddens  by  alkaline  hydroxids  and  carbonates, 
but  not  by  bicarbonates  (PL  6,  Figs.  A,  A').  The  reagent  is 
measured  in  a  Mohr's  buret,  a  glass  tube  i  to  2  cm.  in  diameter, 
graduated  in  cubic  centimeters  and  tenths,  and  closed  below 
by  a  tap  (Fig.  39).  When  supported  upright  the  lower  end  is 
a  narrow-pointed  jet,  connected  by  a  short  joint  of  rubber  tubing, 
closed  by  a  spring  pinch-cock.  If  the  reagent  be  affected  by 
the  rubber,  as  in  the  case  of  silver  nitrate  or  potassium  perman- 
ganate, then  a  glass  cock  takes  the  place  of  the  rubber  and  pinch- 
cock.  The  reagent  for  acidimetry,  normal  solution  of  sodium  or 
potassium  hydroxid,  is  poured  into  the  buret  until  it  rises  above 
the  zero  mark  and  then,  placing  the  bottle  at  the  tap,  the  reagent 
is  run  out  until  the  mark  is  reached;  thus  the  tap  and  jet  are 
filled.  Placing  the  beaker  to  catch  the  outflow,  the  alkaline  solu- 
tion is  run  into  the  mixture  of  acid  liquid  and  indicator,  which  is 
constantly  stirred  until  the  end  of  the  reaction  is  indicated  by. 
the  change  of  color. 

Practical  Application. — To  determine  the  degree  of  acidity 
of  urine  in  terms  of  oxalic  acid  place  in  a  beaker  50  c.c.  of  the 
sample  and  a  strip  of  red  litmus-paper  or  4  drops  of  a  solution 
of  phenolphthalein.  Fill  the  buret  with  decinormal  sodium 
hydroxid,  i  c.c.  of  which  contains  0.004  gm-  of  NaHO,  which 

N 

neutralizes   i   c.c.  of   '--  of  oxalic  acid,  containing   0.0063   °f  tne 
10 

acid.  Run  in  the  alkaline  solution  till  the  red  litmus  turns  blue 
(or  if  phenolphthalein  were  used,  the  colorless  urine  turns  red), 

•    N 
indicating  the  end  of  the  reaction.     If  12.3  c.c.  of  —NaHO  were 

used,  then  12.3X0.0063=0.07749  acidity  in  the  50  c.c.  of  urine, 
equal  to  0.15498  gm.  oxalic  acid  in  100  c.c.  of  urine. 

Alkalimetry. — If  the  sample  be  alkaline  urine,  the  degree  of 
alkalinity  is  determined  by  placing  decinormal  acid  in  the  buret, 
and  tinting  the  urine  with  blue  litmus  or  red  phenolphthalein. 
If  ammonia  be  the  cause  of  the  alkalinity,  methyl  orange  is  the 
best  indicator.  The  acid  is  dropped  into  the  urine  until  the  end- 
point  is  shown  by  the  color  change.  If  the  acid  used  number 
8.3  c.c.,  then  8.3X0.004  =  0.0332,  the  alkalinity  of  50  c.c.  of  urine, 
equal  to  0.0664  gm.  of  sodium  hydroxid  in  100  c.c.  of  urine. 

DISSOCIATION 

From  the  statements  on  p.  123  it  is  clear  that  the  hydrogen 
of  acids  is  not  like  other  hydrogen,  such  as  that  of  water;  the 
hydroxyl  of  bases  is  different  from  the  same  group  in  other  com- 


128 


NON-METALS 


pounds,  such  as  in  hydrogen  peroxid.  The  chlorin  of  the  solu- 
tion of  common  salt  in  precipitating  the  silver  from  the  silver  nitrate 
shows  a  property  shared  by  other  chlorids,  but  peculiar  to  chlorin 
in  a  salt  formed  by  hydrochloric  acid,  not  possessed  by  the  chlorin 
in  many  others  of  its  compounds.  This  property  is  independent  of 
the  nature  of  the  metal  in  the  chlorid.  On  the  other  hand,  the 
metal  of  the  solution  of  base  or  salt  shows  by  its  reactions  that  its 
properties  do  not  depend  upon  the  other  components.  This 
ability  of  each  component  to  act  by  itself  can  be  explained  by  the 
theory  that  in  solution  there  is  a  detachment  of  the  hydrogen 
and  chlorin  of  hydrochloric  acid;  of  the  sodium  and  chlorin  of 
common  salt;  of  the  hydroxyl  and  sodium  of  caustic  soda.  Strong 
confirmation  of  this  view  is  obtained  on  consideration  of  the  fol- 
lowing experiments: 

Electrolytic  Dissociation. — If  an  electrolytic  cell  be  made 
with  two  electrodes  of  platinum,  connected  with  three  or  four 
battery  couples  having  a  galvanometer  or  an  electric  bell  in  the  cir- 
cuit, we  can  test  the  conductivity  of  different  solutions  m  the  glass 
cell.  If  pure  water  be  put  in  the  cell  it  does 
not  conduct  the  electric  current;  therefore, 
the  bell  does  not  ring  nor  the  needle  of  the 
more  sensitive  galvanometer  oscillate.  If 
hydrochloric  acid,  common  salt,  or  sodium 
hydroxid  be  added,  the  current  flows  and  is 
announced  by  the  ringing  of  the  bell  or  the 
oscillation  of  the  needle.  If  the  experiment 
be  made  with  hydrochloric  acid  in  a  vol- 
tameter (Fig.  40),  it  will  be  observed  that 
while  the  current  is  conducted  hydrogen  gas 
escapes  at  the  cathode  (negative  pole)  and 
chlorin  at  the  anode  (positive  pole).  The 
cathode  gas  may  be  lighted  at  the  tap;  the 
anode  gas  bleaches  a  piece  of  wet  litmus- 
paper.1 

Electrolytes     and     Ions.  —  Substances 

which  in  solution  conduct  the  current  and 
are  broken  up  by  it  are  called  electrolytes. 
The  components  into  which  they  are  decom- 
posed were  called  by  Faraday  ions  (movers} 

(p.  50).  The  best  electrolytes  are  those  very  acids,  bases,  and 
salts  we  have  been  studying.  Close  observation  teaches  us  that 
there  is  a  perfect  correspondence  between  their  conductivity  and 

1  The  best  results  are  obtained  by  filling  the  voltameter  with  a  mixture  of  one 
part  of  hydrochloric  acid  to  six  of  a  saturated  solution  of  sodium  chlorid.  The 
chlorin  does  not  appear  as  a  free  gas  until  the  liquid  at  the  positive  end  is  saturated 
with  it. 


FIG.  40. — Voltameter. 


DISSOCIATION  129 

their  chemical  activity.  They  are  believed  to  conduct  the  electricity 
only  by  the  free  ions,  those  that  seek  the  cathode,  such  as  hydrogen 
and  the  metals,  being  called  cations;  those  that  go  to  the  anode 
like  chlorin  and  hydroxyl,  anions.  The  cations  are  supposed 
to  carry  the  positive  electricity  to  the  cathode,  deliver  their  charge, 
and,  uniting  with  like  atoms,  become  molecules;  the  anions  do 
the  same  work  for  the  negative  electricity  and  resume  their  ordinary 
form.  Electrolytes  behave  as  if  their  ions  differed  from  the  same 
elements  or  compounds  in  their  ordinary  state  in  being  energized 
by  electric  charges  which  they  are  free  to  carry  to  the  electrodes. 
This  may  be  indicated  by  separating  the  symbols  with  a  comma 
and  writing  above  them  the  signs  of  positive  and  negative  elec- 
tricity; or  by  using  the  round  point  for  the  cation,  and  the  accent 
marks  for  the  anions,  as  follows: 

HC1      dissociates  into  H,  Cl  or  H*,  Cl' 

NaHO          "  "      Na,  HO  or  Na',  (HO)' 

NaCl  "  "      Na,  Cl  or  Na*,  Cl' 

H2S04          "  "      H,  H,  S=04  or  H',  H',  (SO4)". 

These  are  illustrations  of  the  first  mode  of  ion  formation;  i.  e.,  by 
the  molecules  in  solution  breaking  down  directly  into  an  equivalent 
number  of  anions  and  cations. 

The  ion  reaction  between  dilute  hydrochloric  acid  and  a  weak 
•solution  of  the  base,  sodium  hydroxid,  forming  a  salt,  sodium 
chlorid  and  water,  is  shown  in  either  of  the  following  equations: 

H',C1'     +     Na',(HO)'  Na',Cl'     +     H2O 

H,  Cl       +     Na,  HO         -     Na,  Cl       +     H2O. 

The  ions  of  hydroxyl  and  hydrogen  unite  and  neutralize  each 
other  to  form  undissociated  water,  but  the  ions  of  sodium  and 
chlorin  retain  their  charge  and  their  characteristic  reactions. 

Definitions. — An  acid  is  a  compound  of  hydrogen,  which 
parts  with  its  hydrogen  in  exchange  for  a  metal,  forming  a  salt. 
It  is  acid  because  when  dissolved  it  yields  hydrogen  as  cation. 
If  the  anion  is  simple  the  acid  is  binary,  as  H*,C1',  if  it  is  complex 
the  acid  is  ternary,  as  H',H',(SO4)". 

A  base  is  a  compound  of  hydroxyl  which  neutralizes  an  acid 
forming  a  salt  and  water.     It  is  basic  because  when  dissolved  it 
yields  hydroxyl  as  anion.     The  cation  is  usually  a  simple  metal. 
Bases  are  all  ternary,  as  NaHO. 
9 


130  NON-METALS 

A  salt  is  a  compound  formed  by  the  action  of  an  acid  upon  a  base 
or  a  metal.  It  is  a  compound  of  the  anion  of  an  acid  with  the 
cation  of  a  base. 

The  substitution  of  a  metal  for  the  hydrogen  of  an  acid  is  rep- 
resented in  the  following  equation: 

Zn     +      H-,  Cl'     +      H-,  Cl'     =      Zn",Cl',  Cl'     +      H2 

Atom.  Ions.  Ions.  Molecule. 

The  divalent  zinc  (p.  114)  takes  two  positive  charges  from  the 
monovalent  hydrogen  ions,  becoming  itself  an  ion  carrying  two 
charges,  while  the  hydrogen  ions  having  lost  their  charge,  form 
the  neutral  molecule. 

The  Ions  of  Indicators. — The  characteristic  changes  in  litmus 
and  phenolphthalein  caused  by  acids  and  alkalies  find  an  expla- 
nation in  the  theory  of  a  difference  of  color  between  the  molecule 
of  the  indicator  and  its  ion.  Red  is  the  color  of  the  acidic  mole- 
cule of  litmus,  which,  being  weak,  is  scarcely  dissociable.  When 
the  acid  litmus  is  neutralized  by  an  alkali,  a  salt  is  formed  and 
the  blue  anion  of  litmus  is  set  free.  Phenolphthalein  is  also 
weakly  acidic  and,  therefore,  not  dissociable.  In  this  molecular 
state  it  is  colorless  when  it  is  added  to  water  or  to  the  aqueous 
solution  of  a  strong  acid.  In  the  process  of  titration  a  strong 
base  is  added  until  the  free  acid  is  neutralized.  At  this  point  one 
more  drop  of  the  alkali  unites  with  the  acidic  phenolphthalein 
and  forms  a  dissociated  salt,  of  which  the  complex  organic  anion 
has  a  red  color. 

Hydrolysis. — Weak  acids  and  weak  bases  do  not  give  a  sharp 
change  in  color  because,  when  dissolved,  the  salt  of  a  weak  base, 
like  ammonium  chlorid,  or  of  a  weak  acid,  like  sodium  hypo- 
chlorite,  does  not  break  up  into  the  cation  of  the  metal  and  the 
anion  of  the  other  component,  as  does  sodium  chlorid,  but  into 
the  corresponding  free  acid  and  free  base.  To  do  this  the  water 
itself  breaks  up  very  slightly  into  H*,  (HO)',  yielding,  on  the  one 
hand,  H'  to  make  the  acid  HC1O,  and  on  the  other,  (HO)',  which 
always  gives  the  alkaline  reaction.  The  salt  is  said  to  be  hy- 
drolyzed  because  there  is  decomposition  through  the  agency  of 
water.  The  solution  behaves  as  if  the  acid  and  base  had  not 
neutralized  each  other,  each  giving  its  own  reaction.  Weak  bases 
do  not  give  a  sharp  reaction  to  litmus  or  phenolphthalein,  as  they 
do  not  suddenly  free  the  litmus  in  a  deep  blue,  and  the  other 
indicator  in  a  marked  red  color,  but  form  hydrolyzed  salts  with 
the  indicators,  producing  gradual  changes  of  tints.  Hence,  in 
titrating  for  weak  acids,  litmus  and  a  strong  base,  sodium  or 
potassium  hydroxid,  are  used.  In  such  a  case,  if  phenolphthalein 
be  used  and  the  weak  acids — carbonic,  phosphoric,  or  carbolic — 
be  titrated,  a  slight  change  of  tint  begins  and  deepens  slowly  before 


PLATE  2. 


Arsenous  sulphid  produced  in  hydrogen  sulphid  and  hydrochloric  acid  test 

for  arsenic. 


Cupric  arsenite  produced  in  ammonio-sulphate  of  copper  test  for  arsenic. 


Silver  arsenite  produced  in  arnmonio-nitrate  of  silver  test  for  arsenic. 


Silver  arsenate  produced  in  arsenic  solutions  by  treatment  with  silver 

nitrate. 


Antimonous  sulphid  produced  in  hydrogen  sulphid  test  for  antimony. 


Stannic  sulphid  produced  in  hydrogen  sulphid  test  for  stannic  compounds. 


DISSOCIATION  131 

the  acid  has  been  neutralized.  Nor  does  it  act  sharply  in  the 
opposite  case  when  ammonia  is  titrated,  because  that  is  a  weak 
base  permitting  hydrolysis.  The  practical  conclusions  are:  (i) 
For  weak  acids  a  weak  acidic  indicator,  like  litmus,  may  be  used, 
but  it  must  be  titrated  with  a  strong  base.  (2)  For  weak  bases, 
like  ammonia,  a  strongly  acidic  indicator,  like  methyl  orange,  is 
required,  and  the  titrating  reagent  must  be  a  strong  acid.  In  the 
acidic  molecule  methyl  orange  is  red,  but  converted  by  a  base  into 
a  dissociated  salt,  its  anion  is  yellow. 

lonization  by  Fusion.— As  the  temperature  rises,  many 
solid  substances  increase  in  electric  conductivity  and  when  melted 
become  so  highly  ionized  as  to  conduct  freely  and  undergo  elec- 
trolysis. Many  metals  are  now  separated  from  their  fused  com- 
pounds by  electricity. 

Nomenclature  of  Ions. — For  convenience  of  description  of  the 
reactions  of  ions,  special  terms  have  been  devised,  based  on  a 
system.  The  ion  of  hydrogen  is  called  hydrion,  and  other  cations 
have  their  names  likewise  formed  from  the  stem  of  the  scientific 
name  of  the  metals  and  the  suffix  -ion.  The  ion  of  hydroxyl  is 
called  hydroxidion,  and  other  anions  are  named  likewise  according 
to  the  salt,  those  ending  in  -id  or  -ide  having  the  suffix  changed 
to  -idion.  For  example:  the  chlorin  ion  is  called  chloridion. 
When  the  name  of  the  salt  ends  in  -ate,  the  corresponding  ion  has 
the  suffix  -anion.  For  example:  in  potassium  chlorate  the  two 
ions  are  called  potassion,  K*,  and  chloranion,  (ClOg)';  the  anion 
of  carbonates,  (CO3),"  is  carbanion.  If  the  name  of  a  salt  end 
in  -ite,  the  termination  of  the  name  of  its  anion  is  -osion.  For 
instance:  in  the  salt  sodium  hypochlorite  we  have  sodion,  Na*, 
and  hypochlorosion,  (CIO)'. 

Summary  of  the  Ion  Theory.— It  has  been  shown  that 
when  hydrogen  chlorid  is  dissolved  in  water  the  new  powers  of 
hydrochloric  acid  are  developed,  the  elements  showing  a  different 
energy  from  that  displayed  by  them  in  the  dry  gaseous  state. 
These  new  powers  in  HC1  may  be  accounted  for  upon  the  theory 
that  the  ionized  elements  receive  a  new  charge  of  electricity  when 
the  molecules  are  broken  up,  and  possess  a  much  greater  freedom 
of  action  than  did  the  atoms  in  the  molecule.  The  current  con- 
ducted by  an  electrolyte  is  transported  by  the  simultaneous  move- 
ment of  the  component  ions.  The  quantity  carried  is  propor- 
tional to  the  number  of  and  the  valence  of  the  ions.  Chemical 
diversity  is  regulated  by  electric  relations.  Electric  conductivity 
of  a  solution  should  be  proportional  to  its  number  of  free  ions; 
and  vice  versa,  the  number  of  free  ions  can  be  estimated  by  meas- 
uring the  conductivity.  It  would  follow  also  that  the  total  number 
of  particles — that  is,  molecules  of  NaCl  and  ions  of  Na'  and  Cl' 


132 


NON-METALS 


in  a  normal  solution  of  common  salt  would  be  larger  than  if  none 
of  the  molecules  had  been  dissociated.  As  the  molecules  in  a 
normal  solution  of  a  non-electrolyte,  like  sugar,  are  not  disso- 
ciated, they  do  not  form  so  many  particles  as  do  the  electrolytes. 

In  previous  sections  (pp.  37  and  96)  it  has  been  stated  that 
acids,  bases,  and  salts  in  aqueous  solution  have  more  effect  upon 
the  freezing-point,  the  boiling-point,  and  the  osmotic  pressure  than 
have  sugar,  glycerin,  urea,  and  other  non-electrolytes  when  dis- 
solved in  equivalent  amounts.  These  and  other  physical  abnor- 
malities are  correlated  with  the  peculiar  chemical  and  electrolytic 
behavior  of  electrolytes.  The  changes  of  energy  in  dissolving 
a  substance  correspond  to  the  number  of  particles  dissolved;  and 
the  number  of  free  ions  in  solution  is  indicated  by  the  electric 
conductivity.  From  this  relative  number  of  free  ions  we  estimate 
the  total  relative  number  of  all  particles,  molecules  plus  ions,  and 
with  this  total  calculate  the  lowering  of  the  freezing-point  and 
elevation  of  the  boiling-point.  On  comparing  the  calculated 
results  with  the  observed  facts  so  close  a  mathematic  agreement 
is  found  that  we  can  not  escape  the  conclusion  that  the  theory  of 
ion  dissociation  is  well  founded,  for  it  has  harmonized  phenomena 
widely  at  variance  with  one  another  and  has  furnished  to  practical 
science  working  principles  of  real  value.  The  liquid  in  which 
the  life  functions  of  plants  and  animals  are  performed  is  invariably 
a  dilute  electrolyte  with  a  high  degree  of  dissociation  of  ions. 
By  applying  the  new  conception  to  the  sciences  growing  out  of 
chemistry  it  has  made  intelligible  many  hitherto  unexplained  facts 
in  analysis,  in  color-changes  of  indicators,  in  physiology,  in  bac- 
teriology, and  in  toxicology. 

Dissociants. — Of  the  whole  number  of  molecules  dissolved, 
only  a  fraction  are  usually  dissociated.  The  number  in  this 
fraction  depends  on  the  nature  of  the  solvent  and  the  concentration. 
All  liquids  that  are  solvents  of  acids,  bases,  and  salts  will  also 
dissociate  their  molecules  to  some  degree.  By  using  the  methods 
above  mentioned  for  measuring  dissociation — that  is,  by  freezing- 
point,  boiling-point,  and  electric  conductivity — it  is  ascertained 
that  water  has  more  dissociating  power  than  any  other  liquid. 
Methyl  alcohol  has  from  one-half  to  two-thirds  the  dissociating 
power  of  water,  ethyl  alcohol  not  more  than  half  that  of  methyl 
alcohol,  or  about  one-fourth  that  of  water.  The  hydrocarbons, 
ethers,  aldehyds,  esters,  and  other  derivatives  are  weak  dissociants. 

Effect  of  Solution. — Mention  has  been  made  of  the  fact  that 
when  tested  apart  from  a  solvent  acting  as  dissociant,  dry  chlorin 
does  not  bleach  nor  act  on  sodium,  and  dry  hydrogen  chlorid  does 
not  redden  litmus  nor  liberate  hydrogen  in  the  presence  of  metals. 
Other  experiments  concur  with  these  to  show  that  molecules,  when 


DISSOCIATION  133 

whole,  act  very  little,  if  at  all;  it  is  only  as  they  are  broken  up  into 
ions  that  their  chemical  energies  come  into  play.  In  the  elec- 
trolytes, which  react  with  promptness,  there  are  many  ions;  in 
non-electrolytes,  such  as  the  organic  bodies,  sugar  and  albumin, 
there  are  few  ions,  and  their  reactions  are  much  slower. 

Effect  of  Concentration. — The  degree  of  dissociation  or  the 
fractional  number  of  ions  depends  mainly  on  the  concentration. 
As  the  relative  conducting  power  of  electrolytes  rises  with  the  dilu- 
tion up  to  a  certain  limit,  it  is  assumed  that  when  this  highest 
point  is  reached  dissociation  is  complete.  When  the  strong  acids, 
bases,  and  salts  are  in  very  dilute  solution  it  is  highly  probable 
that  the  relatively  few  molecules  have  all  been  dissociated.  It  is 
discovered  that  at  this  point  of  highest  conductivity  the  acids, 
bases,  and  salts  are  most  active  chemically — that  is  to  say,  that 

/  N  \ 

the  millenormal  (—   —  1  solution  of    HC1  has   more  than  rcrVo  the 
\iooo/ 

activity  of  the  normal  (N)  solution. 

Strength  of  Acids. — As  stated  above,  experiment  shows  that 
the  relative  electric  conductivities  of  acids  vary  as  do  their  chem- 
ical activities.  When  hydrochloric  acid  has  been  diluted  until  it 

N 

is  a  —     -  solution,   the  high  conductivity  makes  it  probable  that 
1000 

its  molecules  have  nearly  all  been  separated  into  free  ions,  but 

N 

the  -     -  solution  of  acetic  acid  has  not  reached  its  highest  con- 
1000 

ductivity,  and  is  believed,  therefore,  to  have  but  few  dissociated 

/N\ 

ions.     When  zinc  is  put  into  equal    volumes  of  decinormal  I  — ) 

\io/ 

hydrochloric  and  acetic  acids  separately,  they  will  each  dissolve 
the  same  weight  of  metal  because  each  contains  the  same  quan- 
tity of  acid  hydrogen.  But  the  velocity  of  their  action  is  very 
different,  hydrochloric  acid  finishing  its  work  much  sooner;  hence 
it  is  said  to  be  more  active.  Nearly  all  the  hydrogen  of  hydro- 
chloric acid  is  at  once  available,  little  of  it  being  held  in  molecules, 
but  with  acetic  acid  some  of  the  hydrogen  ions  must  escape  before 
the  many  undissociated  molecules  dissociate  into  active  ions.  In 
other  words,  the  strongest  acid  chemically  is  the  one  that  is  most 
dissociated,  having  the  highest  proportion  of  free  hydrogen  ions. 
The  degree  of  dissociation  of  the  following  acids  is  about  the  same 
as  that  of  neutral  salt;  they  are  very  active  and  are  called  the  strong 
acids,  i.  e.,  hydrochloric,  hydriodic,  hydrobromic,  chloric,  per- 
chloric, sulphuric,  polythionic,  and  nitric.  Usually  sulphurous, 
phosphoric,  and  acetic  acids  are  not  dissociated  beyond  10  per 
cent,  and  are  called  moderately  strong.  A  dissociation  of  less 


134  NON-METALS 

than  i  per  cent,  characterizes  as  weak  the  acids  sulphydric,  carbonic, 
hydrocyanic,  silicic,  and  boric. 

Analysis. — The  first  act  in  the  analysis  of  salts  is  dissolving 
them  in  water.  In  solution  they  dissociate  into  their  components, 
the  metal  and  the  residue  derived  from  the  acid;  these  have  indi- 
vidual reaction.  As  stated  above,  the  chlorin  in  chlorids  has 
a  peculiar  reaction  with  silver  nitrate  irrespective  of  the  metal  with 
which  it  is  united,  and  different  from  that  in  the  chlorates.  So  it 
is  with  iodids,  sulphates,  and  other  acidulous  factors  of  salts. 
The  metal  in  its  turn  is  sought  independently,  regardless  of  the 
other  constituents.  The  salts  formed  by  copper  with  the  diiferent 
acids  will  yield  to  hydrogen  sulphid  the  same  black  precipitate. 
The  first  step  of  dissolving  the  salt  separated  its  component  ions 
to  such  a  degree  that  the  behavior  of  each  became  independent 
of  the  other. 

Mixed  Solutions. — When  solutions  of  acids,  bases,  and  salts 
are  mixed  without  precipitation  the  free  ions  of  all  of  them  are 
contained  in  the  mixture  and  can  be  identified  by  individual  tests; 
no  matter  how  they  were  arranged  in  the  original  salt.  Thus: 
When  equivalent  amounts  of  sodium  chlorid,  NaCl,  and  potas- 
sium iodid,  KI,  are  mixed  in  solution  they  evolve  no  heat  and  give 
exactly  the  same  reactions  as  does  a  mixture  of  potassium  chlorid, 
KC1,  and  sodium  iodid,  Nal.  When  some  of  the  mixed  ions  can 
unite  to  form  an  insoluble  compound  they  do  so  with  heat  changes, 
forming  a  precipitate.  Thus:  mixed  solutions  of  potassium  iodid, 
KI,  and  lead  nitrate,  Pb(NO3)2,  develop  heat  and  separate  out  the 
undissociated  solid  lead  iodid,  PbI2. 

Ions  of  Consummated  Reactions. — The  reaction  between  two 
active  substances  begins  as  soon  as  they  are  brought  together. 
The  initial  velocity  depends  on  the  temperature  and  the  concen- 
tration (mass)  of  the  solutions.  This  movement  gradually  declines 
until  the  factors  and  the  products  reach  a  certain  concentration, 
when  a  condition  of  equilibrium  is  established  between  the  direct 
and  the  reverse  tendencies  (p.  83).  In  an  operation  where  one  of 
the  reacting  products  escapes  so  fast  that  its  acting  mass  is  never 
present  as  part  of  a  system  in  equilibrium,  the  direct  action  goes  on 
to  completion  thus: 

1.  The  gas  hydrogen  is  set  free  from  an  acid  by  the  substitution 
of  a  metal  (p.  80). 

2.  A  volatile  product  is  distilled  away  by  heat  as  in  the  prepa- 
ration of  hydrochloric  acid  (p.  136). 

3.  An   insoluble   product  is   precipited   by   the   combination   of 
dissolved  ions  into  molecules,  as  when  silver  nitrate  is  acted  upon 
by  a  chlorid,  and  silver  chlorid  thrown  out  of  solution. 

Ag-,  (NO3)'     4      Na',  Cl*     =     AgCl     +     Na',  (NO3)'. 


HYDROCHLORIC    ACID  135 

4.  The  ions  of  a  metal  in  solution  are  deposited  as  atoms  by 
electric  action,  as  in  plating  with  copper. 

Cu**(S04)"     +      H20  Cu     +     H*2(S04)"     +      O. 

Applications  in  Toxicology.— The  poisonous  properties  of 
many  compounds  are  not  the  sum  of  those  of  the  elements  com- 
posing them.  In  this  matter  the  compound  does  not  act  as  a  whole, 
nor  do  the  elements  as  individuals,  unless  they  have  been  ionized. 
A  solution  of  potassium  cyanid  is  very  poisonous,  but  one  of  potas- 
sium ferrocyanid  is  not,  and  yet  cyanogen  is  in  both.  In  the 
first-named  the  poison  exists  as  cyanidion  (CN)',  formed  when 
the  salt  is  first  dissolved.  In  the  second-named,  which  contains 
iron  and  cyanogen,  there  is  no  exhibition  of  the  chemical  or  toxic 
reactions  of  either,  because  the  cation  is  potassion,  and  the  anion 
is  more  complex  than  ferrion  Fe*  or  cyanidion  (CN)',  being 
[Fe(CN)G]"",  ferrocyanidion,  entirely  devoid  of  poisonous  prop- 
erties (pp.  199,  344). 

Silver  salts  are  reduced  in  toxic  effect  by  the  addition  of  sodium 
thiosulphate;  argention,  Ag",  is  lost  in  a  new  complex  ion,  (AgS2O3)' 
which  is  non-toxic,  as  it  does  not  exert  the  same  activity  as  Ag*. 

The  caustic  alkalies  disorganize  and  dissolve  tissue  by  virtue 
of  the  hydroxidion  (HO)'  and  not  because  of  the  metal,  for  sodium 
chlorid  contains  the  metal,  but  is  not  poisonous.  Hydroxyl 
undissociated  is  not  poisonous,  for  if  it  were,  alcohol  in  aqueous 
solution  would  corrode,  as  it  contains  that  group,  though  not  in 
the  state  of  ion. 

The  sulphates  of  potassium,  sodium,  and  magnesium  in  con- 
centrated solution  are  active  cathartics.  They  have  in  common 
the  group  (SO4)'  sulphanion,  and  they  are  all  irritants.  It  is  a 
fair  presumption  that  the  metal  cations  take  no  part  here;  their 
local  effects  are  indifferent  in  their  other  compounds.  The  bowel 
irritation  caused  by  the  sulphates  is  proportional  to  the  relative 
weight  of  sulphanion,  which  is  greatest  in  potassium  sulphate,  and 
least  in  the  magnesium  salt. 

HYDROCHLORIC  ACID   (Acid  Muriatic) 

Formula,  HC1.     Molecular  weight,  36.45. 

Preparation. — The  commercial  muriatic  acid  not  infrequently 
contains  a  trace  of  arsenic.  As  it  is  easier  to  obtain  arsenic- 
free  sulphuric  acid,  the  analyst  sometimes  makes  for  himself  the 
hydrochloric  acid  he  intends  to  use  in  detecting  arsenic.  Fifty 
grams  of  pure  common  salt  are  put  into  a  flask  or  retort  and 
then  is  added  through  a  funnel  tube  dilute  sulphuric  acid,  which 
has  been  mixed  in  advance  and  allowed  to  cool.  To  make  dilute 


i36 


NON-METALS 


sulphuric  acid  30  c.c.  of  the  pure  acid  is  diluted  with  10  c.c.  of 
water.  If  gas  does  not  immediately  escape,  gentle  heat  may  be 
applied  (Fig.  41).  The  gas  is  passed  into  a  suitable  wash-bottle 
in  order  to  charge  the  distilled  water  it  contains. 

NaCl        +        H2S04       ^±1       HC1        +        HNaSO4 

Sodium  chlorid.  Sulphuric  acid.  Acid  hydrochloric.  Sodium  bisulphate. 

This  is  a  reversible  equation,  and  in  the  cold  an  equilibrium  is  set 
up  among  the  four  substances  dependent  on  the  quantities.  When 
part  of  the  volatile  HC1  escapes  by  heat  the  equilibrium  is  destroyed 
and  action  goes  on  to  make  fresh  HC1. 

Official  Preparations. — Acidum  hydrochloricum  contains  31.9 
per  cent,  by  weight  of  anhydrous  HC1.  Dose:  3  to  10  HI 

(0.20-0.66  c.c.),  well  diluted;  in- 
compatible with  alkalies,  chlo- 
rates, chromates,  salts  of  silver, 
mercury,  and  lead,  oxids,  perman- 
ganates, tartar  emetic.  Acidum  hy- 
drochloricum dilutum,  contains  10 
per  cent,  by  weight  of  anhydrous 
HCL  Dose:  10  to  30  tit  (0.66- 
2  c.c.),  well  diluted  with  sweetened 
water. 

Properties. — Commercial  hydro- 
chloric, or  muriatic  acid  is  a  trans- 
parent, yellow,  corrosive  liquid.  Its 
strength  or  percentage  of  pure  acid 
gas  is  approximately  the  product  of 
200  and  the  decimals  of  the  specific 
gravity.  Thus,  a  sample  of  a  specific  gravity  of  1.15  should  contain 
30  per  cent.  HC1  (200X0.15). 

The  chemically  pure  acid  is  colorless,  the  yellow  color  of  the 
commercial  article  being  due  to  a  trace  of  iron  from  the  appa- 
ratus used  in  its  manufacture.  A  more  important  contaminant  is 
arsenic,  taken  from  the  sulphuric  acid  used  in  generating  it.  The 
average  amount  of  this  impurity  is  0.25  per  cent,  of  arsenic  tri- 
oxid.  The  pure  acid  liquid  of  the  U.  S.  Pharmacopoeia  is  sour, 
of  pungent  odor,  and  contains  450  volumes  of  gas  dissolved  in  i 
volume  of  water,  which  increases  more  than  one-third  in  bulk. 

On  exposure  to  the  air  the  strong  acid  gives  off  visible  fumes, 
due  to  the  union  and  condensation  of  the  invisible  gas  with  the 
aqueous  vapor  of  the  air.  The  fumes  have  a  pungent  odor,  an 
acid  taste,  are  irrespirable,  are  one-fourth  heavier  than  the  air,  and 
when  allowed  to  blend  with  the  fumes  of  ammonia  form  dense 
white  clouds  of  ammonium  chlorid.  It  acts  upon  metals  and 


FIG.  41. — Charging  water  with  soluble 
gas. 


HYDROCHLORIC    ACID  137 

bases,  forming  chlorids.  The  acid  dissolves  most  of  the  metals, 
but  not  gold  and  platinum,  and  when  heated  with  manganese 
dioxid,  chlorin  is  set  free.  It  is  the  natural  acid  of  the  gastric 
juice,  and  is  used  with  pepsin  as  an  aid  to  digestion.  It  is  em- 
ployed in  chemical  analysis  as  a  group-reagent,  from  its  having 
the  property  of  precipitating  mercury  (from  mercurous  salts), 
lead,  and  silver. 

The  precipitation  of  silver  salts  occurs  according  to  the  fol- 
lowing equation: 

Ag',(NOs)'     +      H-,  Cl'     =     AgCl     +       H',(N08)' 

Silver  nitrate  Silver  chlorid  Acid  nitric 

ions.  molecules.  ions. 

When  the  ions  of  the  first  half  of  an  equation  can  unite  to  form 
an  insoluble  molecule,  the  union  occurs  and  a  precipitate  falls. 
This  precipitate,  AgCl,  is  soluble  in  ammonium  hydroxid,  but 
insoluble  in  nitric  acid.  A  similar  precipitate  of  mercurous  chlorid 
turns  black  with  ammonium  hydroxid,  while  that  of  lead  chlorid 
under  the  same  conditions  remains  white  and  undissolved. 

Toxicology.— The  Corrosive  Acids.— The  mineral  acids: 
hydrochloric,  sulphuric,  and  nitric,  turn  red  the  vegetable  blue 
colors,  and  change  the  hue  of  dyed  clothing  mostly  to  red  or  yellow, 
and  also  injure  the  texture.  When  concentrated,  they  rapidly 
destroy  organic  substances,  and  on  the  living  body  cause  the  most 
violent  pain.  They  are  simple  corrosives,  causing  well-marked 
symptoms,  due  to  their  action  on  the  part  to  which  they  are  ap- 
plied, complicated  by  the  effects  of  shock  upon  the  system  at  large. 

Hydrochloric  acid  is  very  corrosive,  but  not  so  severe  in  its 
local  action  as  either  sulphuric  or  nitric  acid.  Owing  to  its  vol- 
atility there  is  great  liability  of  acute  laryngeal  inflammation  from 
its  irritating  fumes,  although  the  liquid  itself  may  not  enter  the 
glottis.  The  lips,  tongue,  and  throat  are  first  white,  but  later 
become  brown  and  rotten.  There  are  instant  pain  in  the  mouth, 
throat,  and  abdomen,  difficult  swallowing,  husky  voice,  spas- 
modic breathing,  retching  and  vomiting,  feeble  pulse,  and  general 
weakness,  the  mind  remaining  clear  to  the  last.  If  the  patient 
survive  these  acute  symptoms,  he  remains  subject  to  stricture  of 
the  gullet  or  pylorus,  with  loss  of  function  of  the  stomach. 

Fatal  Dose. — A  few  drops  may  prove  fatal  if  they  enter  the 
larynx.  By  rapid  swallowing  and  quick  transmission  to  the 
stomach  death  may  follow  upon  a  fluidram  dose. 

Fatal  Period. — From  the  acute  effects  death  may  ensue  in 
fifteen  hours  or  even  in  two  hours,  but,  as  a  rule,  the  duration 
of  life  will  be  twenty-four  hours.  The  secondary  consequences 
are  productive  of  a  poor  vitality  for  a  variable  period.  One  case 


138  NON-METALS 

has  been  reported  of  death  from  stricture  of  the  pylorus,  after  four 
months. 

Treatment. — The  remedial  measures  are  the  same  for  hydro- 
chloric as  for  sulphuric  and  nitric  acids. 

The  antidotes  owe  their  power  to  chemical  neutralization, 
changing  the  fiery  acid  to  harmless  neutral  salts. 

Calcined  magnesia,  given  freely,  suspended  in  water  or  milk,  is 
a  perfect  antidote.  When  it  cannot  be  had  at  once,  as  prompt- 
ness is  all-important,  " prepared  chalk,"  "  whiting"  used  to  polish 
silver,  plaster  scraped  from  the  wall,  soapsuds,  or  largely  diluted 
alkalies,  such  as  sodium  carbonate  ("  washing-soda"),  sodium 
bicarbonate  ("bread  or  baking-soda,"  "saleratus"),  sodium  hy- 
droxid  ("  concentrated  lye"),  or  the  corresponding  compounds 
of  potassium,  should  be  given  in  milk  or  water.  It  rarely  happens 
that  the  antidote  is  given  soon  enough  to  prevent  the  energetic 
action  of  the  poison,  and  even  after  thorough  neutralization 
it  would  be  best  to  give  milk  and  very  dilute  alkaline  solutions 
for  some  hours.  As  the  tube  of  the  stomach-pump  or  the  siphon 
impinging  upon  the  softened  structures  may  do  irreparable  harm, 
it  must  not  be  used,  though  later  the  esophageal  stricture  may 
call  for  careful  treatment  by  dilator  and  tubes. 

Postmortem  Appearances. — The  pathologic  changes  found 
after  death  from  hydrochloric  acid  cannot  be  distinguished  from 
those  induced  by  sulphuric  acid,  except  by  the  local  effects  on 
lips  and  face. 

Hydrochloric  acid  leaves  no  permanent  stain  nor  erosion 
externally,  while  sulphuric  acid  discolors  and  nitric  acid  turns  yel- 
low. Internally,  we  find  the  signs  of  intense  inflammation,  with 
a  shriveled  and  worm-eaten  condition  of  the  mucous  membrane, 
which  has  a  white  or  brownish  color.  The  appearances  due  to 
sulphuric  acid  are  the  same,  except  that  the  destruction  of  tissue 
is  greater,  but  the  yellow  marks  of  nitric  acid  are  always  charac- 
teristic. 

Tests. — The  free  acid  gives  the  acid  reaction  to  litmus.  A 
glass  stopper  or  rod  wet  with  it  and  held  near  an  open  bottle  of 
ammonia-water  smokes  with  the  white  clouds  of  ammonium 
chlorid.  Poured  upon  zinc,  it  evolves  hydrogen  gas;  if  heated 
with  manganese  dioxid,  it  yields  greenish-yellow  chlorin  gas  which 
bleaches  a  piece  of  moist  litmus-paper  suspended  in  the  vapor. 

Silver  Nitrate  Test. — The  chief  test  for  chlorids  serves  equally 
for  this  acid — that  is,  silver  nitrate — which  gives  a  heavy,  curdy, 
white  precipitate  of  silver  chlorid,  soluble  in  ammonium  hydroxid, 
but  insoluble  in  nitric  acid. 

As  proof  of  the  presence  of  a  free  mineral  acid,  litmus  will  not 
serve,  as  it  is  affected  by  acid  salts  and  by  the  organic  acid  of 


COMPOUNDS    OF    CHLORIN    CONTAINING    OXYGEN  139 

digestion.  Resort  can  be  had  to  paper  colored  by  certain  anilin 
dyes  which  react  to  minute  quantities  of  free  mineral  acids,  but 
not  in  the  same  way  to  the  organic  acids  nor  to  acid  salts.  A  drop 
of  the  gastric  contents  containing  a  free  mineral  acid  put  on 
Congo-red  paper  leaves  a  dark-blue  spot  (PL  5,  Figs.  2-4)  or 
if  touched  to  Topfer's  yellow  reagent  turns  it  red  (p.  549,  Plate  6, 
Fig.  C). 

Detection. — Very  little  help  is  derived  from  a  study  of  the 
stains  on  clothing.  At  first  a  reddish  spot  appears.  On  some 
black  dyes  the  color  is  greenish,  but  owing  to  the  volatility  of  the 
acid,  the  spots  are  evanescent.  They  are  not  moist,  charred,  nor 
rotten,  as  they  are  from  sulphuric  acid,  nor  are  they  yellow,  as  from 
nitric  acid.  After  a  few  days  the  jnoistened  cloth  will  not  affect 
litmus,  but  if  boiled  in  water,  silver  nitrate  will  show  more  chlorids 
in  it  than  in  the  untouched  cloth. 

In  the  examination  of  the  vomited  matters  we  are  liable  to  a 
fallacy  from  the  natural  presence  of  0.2  per  cent,  of  hydrochloric 
acid  in  the  gastric  juice,  and  from  the  chlorin  in  the  alkaline 
chlorids  of  food. 

If  the  material  be  strongly  acid,  sulphuric  acid  must  first  be 
tested  for  and  excluded.  Distillation  will  then  collect  the  volatile 
hydrochloric  acid,  which  can  be  estimated  by  titration  with  sodium 
hydroxid. 

To  determine  both  free  acid  and  the  combined  chlorids,  first 
make  a  filtered  watery  extract  and  divide  it  into  two  equal  parts. 
One  of  these  is  neutralized  by  adding  an  excess  of  sodium  car- 
bonate, which  fixes  the  volatile  free  acid.  Both  are  evaporated 
to  dryness,  the  unneutralized  portion  losing  all  its  free  acid.  Both 
residues  are  redissolved  in  water  and  are  treated  separately  with 
acid  solution  of  silver  nitrate.  If  the  neutralized  portion  show 
more  chlorids  than  the  other,  the  difference  equals  the  amount 
of  free  hydrochloric  acid  originally  present  in  each  portion.  In 
this  analysis  100  parts  of  silver  chlorid  precipitated  represent 
about  80  parts  of  hydrochloric  acid  (specific  gravity  1.15)  or  25.43 
parts  of  the  anhydrous  acid. 

COMPOUNDS  OF  CHLORIN  CONTAINING  OXYGEN 

Chlorin  and  oxygen  form  two  compounds — chlorin  monoxid, 
C12O,  and  chlorin  tetroxid,  C12O4 — both  of  which  are  unstable 
and  at  times  violently  explosive.  They  are  present  dissolved  with 
free  chlorin  in  liquor  chlori  compositus  (p.  120).  They  have  no 
special  uses  in  medicine  or  in  the  arts  of  everyday  life. 

An  acid  formed  with  hydrogen  and  without  oxygen  is  known 
as  a  hydracid.  To  this  class  belong  HC1,  HBr,  and  HI.  When 
oxygen  is  a  constituent,  the  acid  is  termed  an  oxyacid.  There 


I40  NON-METALS 

are  many  representatives  of  this  class,  and  among  them  are  the 
four  oxyacids  of  chlorin,  which  illustrate  well  the  law  of  multiple 
proportion,  but  are  quite  unstable,  and  of  little  practical  impor- 
tance: 

Hypochlorous  acid HC1O 

Chlorous  acid HC1O2 

Chloric  acid HC1O3 

Perchloric  acid HC1O4 

The  nomenclature  of  these  acids  is  governed  by  the  proportion 
of  oxygen  they  contain.  If  there  be  but  one  acid  to  be  named, 
such  as  hydracid  HC1,  the  termination  -ic  is  used,  and  its  salts 
end  in  -ate.  If  there  be  two  oxyacids,  the  one  containing  the 
smaller  proportion  of  oxygen  has  the  suffix  -ous,  as  chlorous, 
HC1O2;  the  other  -ic  as  chloric,  HC1O3.  The  names  of  salts  of 
acids  ending  in  -ous  are  formed  by  adding  to  the  stem  the  suffix 
-ite.  When  an  element  forms  more  than  two  oxyacids,  the  prefix 
hypo-  is  given  to  the  acid  having  less  oxygen  than  the  -ous  acid, 
as  hypochlorous;  and  the  prefix  per-  to  the  acid  having  more  than 
the  -ic  acid,  as  perchloric.  In  the  above  list  will  be  found  four 
acids  named  according  to  this  system,  only  two  of  which,  however, 
are  of  interest  to  us — hypochlorous  and  chloric. 

Hypochlorous  Acid.— Calx  Chlorinata.— When  slaked  lime 
is  exposed  to  the  action  of  chlorin  gas  for  about  sixteen  hours, 
it  takes  up  the  chlorin  and  forms  the  commercial  product  known 
as  chlorid  of  lime,  or  bleaching  powder,  the  official  name  being  calx 
chlorinata  in  U.  S.  P.  Not  markedly  deliquescent,  it  probably 
does  not  contain  calcium  chlorid,  for  that  compound  is  deliquescent 
to  a  high  degree.  The  composition  of  calx  chlorinata  is  repre- 

Cl 

sented  by  the  formula  Ca(ClO)Cl,  or  Ca<rl  •  and  its  manufac- 
ture by  the  equation: 

Ca(HO)2     +     C12     =     Ca(C10)Cl     +     H2O. 

Lime.  Calx  chlorinata. 

Treated  with  water,  calx  chlorinata  dissolves,  changing  into 
calcium  chlorid  and  calcium  hypochlorite: 

2Ca(C10)Cl  CaCl2         +          Ca(ClO)2. 

The  bleaching  action  of  calx  chlorinata  is  demonstrable  by 
smearing  a  printed  page  with  writing  ink,  dipping  the  page  into 
a  dilute  solution  of  calx  chlorinata,  and  while  wet  transferring  it 
to  weak  hydrochloric  acid.  Any  textile  fabric  so  treated  will 
have  nascent  oxygen  and  chlorin  set  free  in  its  meshes.  The 
carbon  of  the  printers'  ink  will  not  be  affected. 


COMPOUNDS    OF    CHLORIN    CONTAINING    OXYGEN  141 

Ca(ClO)2    +    2HC1    =    CaCl2    +    H2O    +    C12    +    O. 

Calcium  Calcium  Nascent 

hypochlorite.  chlorid.  oxygen. 

A  solution  of  calx  chlorinata,  i  pound  to  the  gallon  of  water, 
represents  in  a  more  stable  form  all  the  disinfecting  powers  of 
chlorin  water,  and  is  extensively  used  as  a  deodorizer  and  germicide. 
Exposed  to  the  air  it  evolves  chlorin  spontaneously. 

When  calcium  hypochlorite  is  acted  upon  by  very  dilute  nitric 
acid  and  the  product  distilled,  dilute  hypochlorous  acid  is  ob- 
tained. 

Ca(C10)2     +     2HN03     =     Ca(N03)2     +     2HC1O 

Calcium  Nitric  Calcium  Hypochlorous 

hypochlorite.  acid.  nitrate.  acid. 

Properties. — Hypochlorous  acid  has  not  yet  been  formed  abso- 
lutely dry.  In  aqueous  solution  it  has  the  strong  smell  of  chlorin, 
but  not  the  greenish  hue  of  chlorin  water.  It  does  not  keep  well, 
soon  breaking  up  into  oxygen  and  hydrochloric  acid.  As  it 
yields  a  ready  supply  of  active  oxygen  it  has  the  same  bleaching 
and  germicidal  powers  possessed  by  chlorin-water. 

HC1O       =       O       +       HC1. 

Tests. — Owing  to  the  constant  presence  of  some  hydrochloric 
acid  it  yields  a  white  precipitate  with  silver  nitrate.  It  decolorizes 
litmus  and  indigo  in  solutions. 

Sodium  hypochlorite,  NaCIO,  is  known  only  in  the  official 
liquor  soda  chlorinata,  Labarraque's  fluid,  which  contains  NaCl 
+  NaCIO,  and  is  prepared  by  decomposing  solution  of  calx  chlo- 
rinata by  sodium  carbonate,  or  by  passing  chlorin  into  a  solution 
of  caustic  soda:  2NaHO  +  2Cl  =  NaCl  +  NaClO  +  H2O.  It  is  more 
permanent  than  chlorin-water,  but  undergoes  a  change  in  time, 
losing  its  chlorin  smell  and  bleaching  power  and  the  property 
of  yielding  chlorin  when  treated  with  dilute  hydrochloric  acid, 
due  to  the  loss  of  its  hypochlorite.  On  evaporation  sodium 
chlorid  is  obtained,  and  another  salt  having  the  composition 
NaClO3,  called  sodium  chlorate: 

3NaClO    =    2NaCl    +    NaClO3 

Sodium  hypochlorite.  Sodium  chlorate. 

If  caustic  potash,  KHO,  had  been  used,  then  potassium  hypo- 
chlorite would  have  formed,  changing  to  potassium  chlorate, 
KC1O3,  a  well-known  salt  already  referred  to  as  a  source  of  oxygen. 
By  electrolysis  of  a  solution  of  this  salt,  potassion  K*  moves  to  the 
cathode  and  chloranion  (C1O3)'  to  the  anode.  As  the  chlorin  is 
here  part  of  a  complex  anion  it  is  not  surprising  that  this  salt  does 
not  precipitate  silver  chlorid  from  solution  of  silver  nitrate  (p.  137). 


I42  NON-METALS 


OTHER  HALOGENS 

BROMIN    (Bromum) 
Symbol,  Br.     Atomic  weight,  79.96. 

Occurrence. — Though  met  in  smaller  quantities  than  chlorin, 
which  it  closely  resembles,  bromin  is  widely  distributed  in  nature. 
In  the  residues  of  evaporation  of  sea-water  bromin  compounds 
of  sodium  and  magnesium  are  found,  and  from  these  the  element 
is  liberated. 

Preparation. — The  reactions  by  which  bromin  is  made  are 
parallel  to  those  used  for  chlorin.  By  electrolysis  of  bromids  the 
bromidion  moves  to  the  anode  and  separates  as  free  bromin,  the 
metal  going  to  the  cathode.  By  another  method  the  bromids  in 
sea  salt  are  in  one  operation  converted  to  hydrobromic  acid,  and 
this,  oxidized  by  manganese  dioxid,  loses  its  hydrogen,  leaving  free 
bromin. 

2NaBr       +       H2SO4       =       Na2SO4       +       2HBr 

Sodium  bromid.  Sodium  sulphate.       Hydrobromic  acid. 

2HBr       +       O       =       H2O       +       Br2. 

This  process  is  facilitated  by  the  free  chlorin  formed  from  the 
chlorids  present  in  the  salt;  or  chlorin  may  be  obtained  outside 
and  passed  into  the  brine.  It  decomposes  the  bromids  and  the 
bromin  distils  over. 

Properties.— Physical.— Bromin  is  a  dark,  reddish-brown 
liquid,  opaque  in  thick  layers,  with  a  specific  gravity  of  3.1.  At 
ordinary  temperatures  it  vaporizes  in  red  fumes  of  an  unpleasant 
odor  and  is  highly  irritating  to  the  mucous  membrane  of  the  nose 
and  air-passages.  It  should  be  held  at  arm's  length  in  handling. 
It  boils  at  60°  C.  (140°  F.)  and  solidifies  at  -7°  C.  (19°  F.), 
forming  a  dark  crystal.  It  is  soluble  in  alcohol,  ether,  and  chlo- 
roform. At  room  temperature  it  dissolves  3  per  cent,  in  water, 
making  a  brown-yellow  liquid  with  the  properties  of  bromin.  This 
solution  is  used  as  a  reagent  under  the  name  of  bromin-water. 
Exposed  to  light,  bromin-water  decomposes,  forming  hydrobromic 
acid.  ^  When  the  water  already  contains  a  bromid  in  solution,  the 
bromin  dissolves  in  larger  amount,  forming  compounds  that 
readily  decompose  and  behave  in  a  manner  similar  to  free  bromin. 
There  is  no  more  free  bromin  in  solution  than  would  be  the  case 
if  water  alone  were  the  solvent,  but  the  salt  holds  the  bromin  as 
the  brown-colored  ion,  Br'3  (tribromidiori).  In  any  reaction  the 
bromid-salt  solution  yields  fresh  bromin  to  the  water  as  fast  as  the 


BROMIN  143 

free  bromin  is  removed.  The  ion  Br'3  splits  into  Br'  +  Br2,  which 
is  to  say,  the  tribromidion  yields  bromidion  and  neutral  bromin. 

Chemical. — The  behavior  of  bromin  is  similar  to  that  of  chlorin, 
but  its  activity  is  less.  It  is  a  monad,  combines  with  many  ele- 
ments directly,  and  unites  with  arsenic  with  so  much  avidity  as  to 
evolve  heat  and  light.  If  powdered  magnesium  be  shaken  with 
bromin-water  the  color  disappears,  and  after  filtering  off  the  metal 
a  solution  of  (MgBr2)  magnesium  bromid  remains.  If  this  is 
decomposed  in  an  electrolytic  cell  yellowish  bromin  is  liberated  at 
the  anode,  while  at  the  cathode  white  magnesium  hydroxid, 
Mg(HO)2  and  bubbles  of  hydrogen  appear.  The  free  magnesium 
has  taken  hydroxyl  from  water  and  set  free  the  hydrogen. 

Medical  Uses. — Bromin  has  been  given  internally  in  doses  of 
i  to  3  TTL  (0.06-0.18  c.c.),  well  diluted;  externally  as  an  antiseptic 
in  i  per  cent,  lotions,  or  as  caustic,  used  pure  or  with  equal  parts  of 
alcohol.  The  alkaline  bromids  are  given  internally  as  sedatives, 
hypnotics,  and  antispasmodics.  It  is  incompatible  with  caustic 
alkalies,  arsenites,  ferrous  salts,  hypophosphites,  hydriodic  acid, 
and  mercurous  salts. 

Toxicology. — Symptoms. — Bromin  vapor  when  inhaled  causes 
symptoms  of  violent  catarrhal  inflammation  of  the  air-passages, 
with  cough,  constriction  of  the  chest,  and  hemoptysis.  It  acts 
vigorously  as  a  caustic  on  organic  matter,  producing,  when  swal- 
lowed, pain  in  the  mouth,  throat,  and  stomach,  with  eructation 
of  the  peculiar  offensive  vapor.  Its  powerful  local  action  may 
bring  on  collapse  in  a  few  hours. 

Fatal  Dose  and  Period. — Very  few  cases  of  death  have  been 
reported.  One  was  caused  by  i  oz.  of  bromin.  In  another  fatal 
case  a  child  of  ten  took  what  was  calculated  to  be  about  2  gr.  of 
bromin.  Fatal  collapse  has  come  on  within  seven  hours. 

Treatment. — If  it  has  been  swallowed,  complete  evacuation 
must  be  secured  by  emetics  (5  TTL  of  a  2  per  cent,  solution  of  apo- 
morphin  hydrochlorate)  and  the  stomach-pump.  The  chemical 
antidotes  are  protectives,  such  as  raw  eggs,  mucilaginous  drinks 
made  from  starch,  arrow-root,  barley,  rice,  flour,  or  meal.  If 
bromin  has  been  inhaled,  ammonia  vapor  and  steam  must  be 
inhaled  as  antidotes.  For  depression  whisky  may  be  given. 

Postmortem  Appearances. — A  dark-brown  stain  marks  the 
point  of  local  action;  the  mucous  membrane  is  inflamed,  softened,, 
loosened,  or  even  corroded. 

Detection. — The  element  may  be  identified  by  its  color  and 
odor.  If  it  be  present  as  bromidion  in  a  bromid,  the  bromin 
must  be  freed  by  adding  a  little  chlorin-water.  The  chlorin 
becomes  chloridion  and  the  bromidion  changes  to  neutral  bromin 
with  its  characteristic  brownish  color,  K*Br'+  Cl=  K'Cl'4-Br. 


144  NON-METALS 

When  bromin-water  is  shaken  with  chloroform,  the  latter  takes  up 
the  bromin  and  separates  it  in  a  brownish-yellow  layer.  Starch- 
water  forms  the  bromid  of  starch,  which  is  of  a  deep  yellow  color. 

"Bromism." — This  name  has  been  given  to  the  poisonous 
effects  of  long-continued  dosing  with  bromids.  The  symptoms 
are  the  fetid  odor  of  bromin  on  the  breath,  mental  dulness,  ner- 
vous depression,  muscular  weakness,  absence  of  sexual  feeling, 
eruptions  of  acne,  bullae,  and  pustules.  When  pushed  to  the 
extreme,  the  bromids  have  caused  exhaustion  and  fatal  heart 
failure. 

Hydrogen  bromid,  HBr,  is  a  colorless  gas  readily  soluble  in 
water,  forming  acidum  hydrobromicum  dilutum  (U.  S.  P.),  which 
is  a  lo-per  cent,  solution  of  hydrogen  bromid,  resembling  hydro- 
chloric acid  in  chemical  properties,  but  medically  having  the 
sedative  action  of  bromids.  It  is  given  to  allay  cough  in  doses 
of  30  to  90  HI  (1.90-5.70  c.c.)  in  sweetened  water. 

The  bromids  in  general  are  formed  like  the  chlorids  and 
have  similar  properties. 

Like  the  chlorids,  they  are  quite  soluble,  except  the  bromid 
of  silver,  the  mercurous  bromid,  and  the  lead  salt,  which  are 
almost  insoluble.  The  silver  bromid  is  insoluble  in  nitric  acid 
and  sparingly  soluble  in  ammonium  hydroxid. 

The  reaction  with  silver  nitrate  is  as  follows: 

K',Br'     +      Ag',  (N03)'  K',(NOS)'     +      AgBr. 

The  precipitate  AgBr  does  not  form  unless  the  bromin  is  dis- 
sociated as  bromidion.  Thus  in  ethyl  bromid,  C2H5Br,  a  non- 
electrolyte,  the  bromin  is  not  ionized  and  there  is  no  reaction  with 
the  silver  ion. 

Oxyacids. — Three  oxyacids  are  known  and  they  are  more 
permanent  than  the  corresponding  compounds  of  chlorin.  They 
are  hypobromous  acid,  HBrO;  bromic  acid,  HBrO3;  and  per- 
bromic  acid,  HBrO4. 

IODIN    (lodum) 
Symbol,  I.     Atomic  weight,  126.85. 

Occurrence. — In  nature  iodin  is  found  combined  with  potas- 
sium, sodium,  calcium,  and  magnesium  in  sea-water,  in  sea  ani- 
mals, and  sea  plants. 

Preparation.— The  ashes  of  the  seaweed  called  kelp  are 
extracted  with  water,  and  by  evaporation  the  other  salts  crystal- 
lize out,  leaving  a  mother  liquor  containing  the  iodids.  Chlorin, 
obtained  from  bleaching  powder,  decomposes  the  iodids  and  free 
\odin  distils  over.  With  potassium  iodid  the  reaction  is: 

K-,F     +     Cl     =     K-,C!'     +     I. 


IODIN  145 

Properties.— Physical.— lodin  deviates  from  bromin  in  the 
same  direction  that  bromin  deviates  from  chlorin:  chlorin  is  a 
gas,  bromin  a  liquid,  and  iodin  a  solid.  Its  crystals  are  blue- 
black,  soft,  and  scaly,  having  a  metallic  luster  and  an  unpleasant 
taste.  The  specific  gravity  of  iodin  is  5;  it  melts  at  114°  C. 
(237°  F.)  and  boils  at  175°  C.  (347°  F.).  At  all  temperatures 
iodin  gives  off  a  vapor  possessing  a  characteristic  odor  and  a 
violet  color,  to  which  latter  the  name  of  the  element  is  due  (iodes, 
violet}.  If  a  large  flask  be  strongly  heated  by  constant  turning 
over  a  large  flame,  and  a  few  crystals  of  iodin  be  then  thrown  in, 
a  heavy  vapor  of  a  dark  violet  color  forms.  The  specific  gravity 
of  this  vapor  is  8.716. 

The  crystals  are  only  sparingly  soluble  in  water,  but  if  an 
excess  of  iodin  be  left  in  the  bottle  in  time  a  larger  amount  is 
taken  up,  some  of  it  passing  into  the  state  of  hydriodic  acid  (HI) 
by  a  decomposition  of  water  similar  to  that  caused  by  chlorin 
and  bromin.  This  hydriodic  acid  assists  in  dissolving  the  iodin. 
If  the  water  contain  an  iodid,  such  as  potassium  iodid,  much 
larger  quantities  of  iodin  pass  into  solution. 

This  phenomenon,  like  a  similar  one  described  under  Bromin 
(p.  142),  is  due  to  the  formation  of  an  easily  decomposed  com- 
pound, in  which  the  colorless  iodidion,  F,  of  the  salt  becomes 
brown  tri-iodidion,  I3'.  In  using  it,  as  fast  as  the  free  iodin  is  taken 
away,  the  I3'  is  broken  up  to  F  in  the  iodid  and  neutral  iodin  I2, 
which  replaces  the  free  iodin  in  solution.  This  property  is  em- 
ployed in  the  highly  iodinized  official  preparations,  all  of  which 
contain  potassium  iodid  as  well  as  iodin,  tinctura  iodi,  liquor 
iodi  compositus,  or  LugoVs  solution;  unguentum  iodi,  or  LugoVs 
ointment,  and  also  Churchill's  tincture. 

Iodin  is  very  soluble  in  alcohol,  forming  the  dark  red-brown 
tincture  (7  per  cent,  of  iodin).  When  dissolved  in  ether  it  has 
the  same  red-brown  color,  but  in  chloroform,  benzene,  and  carbon 
disulphid  its  solutions  are  a  fine  violet  color.  As  carbon  disulphid 
is  a  heavy  colorless  liquid  not  miscible  with  water,  it  may  be 
used  to  show  the  phenomenon  of  separation  by  the  difference 
of  solubility,  which  is  as  i  :  700.  The  brown  solution  of  iodin 
in  water  loses  its  color  when  shaken  with  carbon  disulphid,  the 
disulphid  being  turned  a  deep  violet  and  separating  as  a  bottom 
layer.  That  this  applies  only  to  the  elementary  iodin  is  shown 
by  adding  potassium  hydroxid  to  the  water  and  shaking  the 
fluids  again.  The \violet  color  disappears  from  the  carbon  disulphid 
as  the  iodin  changes  to  potassium  iodid  and  passes  into  its  better 
solvent,  the  water. 

Chemical. — Closely  akin  to  chlorin  and  bromin  in  its  reactions, 
iodin  is  less  active  than  either.  It  has  feeble  bleaching  and 


146  NON-METALS 

oxidizing  powers  and  decomposes  water  slowly.  Ozone  forms 
an  oxid  with  it,  but  oxygen  does  not.  Ammonium  hydroxid  con- 
verts iodin  into  an  explosive,  nitrogen  iodid.  It  is  oxidized  by 
nitric  acid  into  iodic  acid. 

Amylum  iodatum,  or  starch  iodid,  is  a  compound  having 
a  deep-blue  color,  and  is  formed  when  a  cold  solution  of  boiled 
starch  is  treated  with  free  iodin.  Although  this  is  a  compound, 
yet  as  the  union  is  not  very  strong,  it  has  to  some  degree  the 
chemical  and  medical  properties  of  iodin.  This  characteristic 
reaction  is  used  to  detect  both  starch  and  iodin.1  Should  the 
indications  be  doubtful,  the  blue  fluid  may  be  heated,  when  the 
blue  starch  iodid  will  dissociate  and  the  brown  color  of  free  iodin 
appear.  When  cooled,  the  blue  compound  is  restored. 

lodids  have  a  resemblance  to  the  chlorids  and  bromids,  and 
are  formed  by  similar  reactions.  All  the  metallic  iodids  are  sol- 
uble, except  those  of  silver,  lead,  and  the  mercurous  salt.  The 
lead  iodid  is  feebly  soluble.  Chlorin  displaces  iodin  as  it  does 
bromin. 

Incompatibles.— The  alkalies,  alkaloids,  metallic  salts,  starch, 
tannin,  and  turpentine. 

Medical  Uses. — Free  iodin  is  a  local  escharotic,  discutient 
and  disinfectant.  Internally,  it  is  an  alterative  for  scrofulosis. 

Toxicology. — By  mistake,  though  rarely,  the  tincture  and 
the  liniment  have  been  taken  internally  with  poisonous  effects. 

Symptoms. — It  acts  as  a  powerful  irritant  upon  the  stomach 
and  bowels,  causing  pain  in  the  mouth,  throat,  and  stomach, 
vomiting  and  purging,  extreme  thirst,  fainting  attacks,  and  col- 
lapse. When  applied  by  surgeons  freely  to  absorbing  surfaces, 
it  may  cause  systemic  disturbances,  such  as  headache,  dizziness, 
mental  trouble,  along  with  the  above  gastric  symptoms  brought 
about  indirectly.  Its  elimination  by  the  kidneys  involves  those 
organs  in  inflammation,  which  may  end  in  suppression  of  urine. 

Fatal  Dose. — Death  has  resulted  from  i  fl.  dr.  of  the  tincture, 
containing  less  than  2  gr.  of  the  element.  Ten  or  20  gr.  of  the 
solid  would  probably  be  fatal.  Recovery  has  followed  a  dose  of 
i  fl.  oz.  of  the  tincture. 

Fatal  Period. — While  death  has  occurred  in  twenty-four  hours, 
in  cases  of  poisoning  from  external  application  it  will  be  delayed 
for  several  days. 

Treatment. — Large  drafts  of  tepid  water  will  assist  in  evacu- 
ating the  stomach.  The  antidote  is  starch  in  some  form,  best  given 
in  decoction,  such  as  the  clear  starch  of  the  laundry;  or  as  gruels, 

1 A  sensitive  starch  paste  is  best  made  by  grinding  a  small  amount  of  laundry 
starch  in  a  mortar  with  cold  water  and  then  pouring  it  into  hot  water  at  the  boiling- 
point  while  stirring.  Heat  is  withdrawn  and  after  cooling  the  thin,  clear  solution 
detects  the  merest  trace  of  iodin. 


IODIN  147 

boiled  rice,  or  arrow-root,  given  as  long  as  the  vomited  matters 
have  a  blue  color. 

Postmortem  Appearances. — The  morbid  changes  found  are 
such  as  attend  gastro-intestinal  irritation,  leading  to  inflammation 
and  excoriation. 

Detection. — By  agitating  organic  matters  or  an  aqueous  solu- 
tion of  iodin  with  carbon  bisulphid  the  iodin  is  separated,  making 
a  violet-colored  solution.  If  the  iodin  is  combined,  a  very  small 
quantity  of  chlorin-water  must  be  used  to  liberate  it.  A  decoction 
of  starch  which  has  been  allowed  to  cool  gives  a  dark-blue  color, 
due  to  the  formation  of  iodid  of  starch.  The  yellow  stains  on  the 
skin  and  lips  are  removable  by  ammonia,  which  would  only  deepen 
the  stain  if  due  to  nitric  acid. 

"lodism." — Excessive  doses  of  iodids  or  the  persistent  use  of 
average  doses  may  induce  the  symptoms  of  "iodism."  These 
are  frontal  headache,  catarrh,  general  malaise.  The  face  swells 
and  skin  eruptions  appear.  Fatal  cases  are  rare. 

Hydrogen  Iodid. — This  is  a  colorless  gas  having  the  for- 
mula HI,  and,  like  HC1,  dissolves  freely  in  water,  forming  hydri- 
odic  acid.  This  acid  closely  resembles  the  hydracids  of  chlorin 
and  bromin,  and  can  be  prepared  by  passing  hydrogen  sulphid 
through  an  aqueous  solution  of  iodin  until  the  latter  is  decolor- 
ized: 

H2S  +          I2  2HI          +        S. 

Hydrogen  sulphid.  Hydriodic  acid. 

If  allowed  to  stand  in  the  air,  the  colorless  acid  becomes  oxi- 
dized, turns  brown,  and  eventually  disappears,  while  crystals  of 
free  iodin  form. 

4HI      +     O2      =     2H2O    +       2l2. 

Syrupus  acidi  hydriodici  (U.  S.  P.)  contains  i  per  cent, 
absolute  HI.  Dose:  30  to  60  TTL  (1.90-3.80  c.c.). 

Acidum  hydriodicum  dilutum  (U.  S.  P.)  is  a  10  per  cent,  aqueous 
solution  of  HI  made  by  the  action  of  tartaric  acid,  potassium  iodid,  and 
hypophosphite. 

Oxyacids. — The  effect  of  mixing  iodin  with  caustic  soda  corre- 
sponds to  that  of  mixing  chlorin  with  the  same  hydroxid.  First, 
the  hypoiodite,  NalO,  is  formed;  in  a  short  while  this  changes 
to  sodium  iodate,  NaIO3,  and  sodium  iodid,  Nal.  The  acid  from 
which  the  iodate  is  derived  is  iodic  acid,  HIO3. 

lodic  acid  is  a  very  stable,  white  crystalline  substance,  soluble 
in  water  and  imparting  to  it  the  properties  of  a  strong  acid.  It  is 
odorless  and  has  a  bitter  taste.  It  is  used  as  a  test  for  morphin, 
as  it  yields  its  oxygen  readily  and  is  thus  reduced  to  brown  ele- 
mentary iodin. 


148  NON-METALS 

Periodic  acid,  HIO4,  is  formed  when  sodium  iodate  is  oxidized 
by  the  action  of  chlorin.  Taking  up  i  atom  more  of  oxygen, 
sodium  periodate  is  produced.  From  this  salt  the  acid  can  be 
obtained  as  colorless  crystals,  soluble  in  water  and  decomposable 
by  heat.  In  this  form  it  has  2  molecules  of  water  combined  with 
it,  giving  a  formula  H5IO6. 

FLUORIN 

Symbol,  F.     Atomic  weight,  19.05. 

Occurrence. — In  nature  fluorin  exists  in  large  quantities  as 
fluorspar,  calcium  fluorid,  CaF2,  and  in  cryolite,  a  fluorid  of  alu- 
minium and  sodium,  Na3AlFb.  Like  the  other  halogens,  fluorin 
is  not  found  free  in  nature,  owing  to  its  active  affinities  for  many 
substances. 

Preparation. — When  anhydrous  hydrogen  fluorid  is  con- 
verted into  a  conductor  by  dissolving  in  it  calcium  fluorid,  the 
hydrogen  fluorid  is  decomposed  by  the  electric  current,  with 
fluorin  separating  at  the  anode.  Vessels  of  platinum  or  copper 
resist  the  fluorin  fairly  well  and  are  used  instead  of  glass. 

Properties. — Fluorin  is  an  almost  colorless,  faintly  yellow 
gas  with  a  specific  gravity  of  1.265.  ^  *s  condensed  to  a  liquid 
at  —187°  C.  (  —  304°  F.).  It  combines  with  every  element  except 
oxygen  and  the  argon  family,  and  generally  with  great  energy. 
All  sorts  of  hydrogen  compounds  yield  their  hydrogen  to  it,  with 
the  evolution  of  light  and  heat. 

Hydrogen  Fluorid  (HF).— This  gas  is  prepared  by  gently 
heating  in  a  lead  dish  a  mixture  of  calcium  fluorid  and  sulphuric 
acid.  If  it  be  covered  with  a  glass  plate  the  glass  is  corroded 
wherever  it  is  exposed.  By  previously  coating  the  glass  with 
wax  or  paraffin  and  scratching  with  a  needle  through  the  wax  the 
glass  may  be  etched  in  ruled  lines  or  ornamental  figures.  In 
this  experiment  aqueous  vapor  mixes  with  the  gas.  When  abso- 
lutely dry  the  gas  does  not  act  on  glass.  The  reaction  is  as  follows: 

CaF2        +        H2SO4  2HF        +        CaSO4 

Calcium  fluorid.  Calcium  sulphate. 

Hydrofluoric  Acid. — The  gas  dissolved  in  water  becomes  a 
fuming  liquid,  which  can  not  be  kept  in  glass.  Gutta-percha  bot- 
tles, however,  resist  the  action  of  the  acid  and  are  used  as  con- 
tainers. The  reaction  with  glass  is  shown  in  the  following  equa- 
tion to  be  a  conversion  of  the  silicic  acid  into  a  gas,  silicon  fluorid: 

SiO2          +          4HF  2H2O          +          SiF4 

Silicic  acid.  Hydrofluoric  acid.  Silicon  fluorid. 

Toxicology. — Like  hydrogen  chlorid,  this  gas  is  highly  irri- 
tating when  inhaled,  and  the  liquid  acid  corrodes  the  parts  with 


THE    CHLORIN    FAMILY  149 

which  it  comes  in  contact.  The  antidote,  when  inhaled,  is 
ammonia  vapor;  or,  on  the  burned  surfaces,  weak  alkalies  to 
neutralize  the  acid. 

Sodium  ftuorid  is  sometimes  added  to  beer  as  a  preservative. 
The  amount  in  a  single  bottle  has  no  noticeable  effect,  but  if  the 
preserved  beer  is  taken  habitually  as  a  beverage  the  effects  accumu- 
late. They  are  seen  in  the  neuralgias,  weak  heart,  dropsies, 
phlebitis,  painful  urination,  and  loss  of  calcium  salts  from  the 
system,  impairing  nutrition  of  the  bones. 

THE  CHLORIN  FAMILY  OR  HALOGENS 

In  a  former  section  a  list  of  the  elements  was  given  (see  p.  117), 
arranged,  according  to  a  natural  system,  by  their  numeric  pro- 
gression in  valence  ajid  atomic  weights.  This  system  was  based 
upon  the  observation  that  in  many  cases  elements  that  resemble 
one  another  could  be  grouped  in  triplets,  the  middle  member  of 
which  was  not  only  intermediate  in  properties,  but  also  had  an 
atomic  weight  very  nearly  the  mean  of  two  extremes.  Thus,  in 
the  order  of  atomic  weights,  0  =  35.5,  Br  =  8o,  1=127,  the  mean 
is  81.25. 

35-5        +       127        =       81.25. 


Other  examples  are  P  =  3i,  As  =  75,  Sb=i2o,  the  mean  75.5. 
The  calcium  group:  Ca  =  4o,  Sr  =  87.5,  Ba=i37,  the  mean  is 
88.5. 

The  similarities  of  the  chlorin  group  with  the  gradation  in 
properties  according  to  the  atomic  weights  are  shown  in  the  fol- 
lowing summary:  They  are  all  univalent,  all  volatile,  and  all 
form  colored  gases  that  are  pungent  and  irritating.  At  room 
temperature  Cl  is  a  gas,  Br  is  a  liquid,  I  a  solid.  Their  boiling- 
points  rise  in  the  same  order  with  their  specific  gravities.  In 
their  chemical  conduct  and  their  bleaching  and  disinfectant  powers 
Cl  has  the  strongest  affinities,  Br  next,  and  I  last;  thus  illustrating 
a  general  principle,  that  in  such  a  group  the  energy  is  inversely 
as  the  atomic  weight.  The  lighter  halogen  always  displaces  the 
heavier  from  its  salts,  i.  e.,  the  lighter  forms  ions;  the  heavier, 
elementary  molecules.  The  tendency  to  ion  formation  is  great 
in  fluorin  but  very  slight  in  iodin.  The  activity  and  stability  of 
their  hydrogen  acids  follow  the  same  law,  but  the  order  for  the 
oxygen  acids  is  reversed.  As  for  solubility  in  water,  Cl  is  readily 
soluble,  Br  moderately,  I  feebly.  Their  salts  with  metals  (called 
haloid}  crystallize  in  cubes  and  are  among  the  best  germicides 
known.  These  elements  are  called  halogens  (hals,  sea-salt) 
because  they  are  generated  from  the  sea:  Cl  from  sea-water,  Br 


150  NON-METALS 

from  sea-salt,  I  from  seaweed.  Fluorin  is  classed  with  the  halo- 
gens, though  there  is  a  wider  step  from  it  to  chlorin  than  there  is 
between  the  other  members  of  the  series.  It  resembles  the  mem- 
bers of  this  group,  however,  more  than  it  does  those  of  any  other. 
Facts  like  those  just  stated  might  be  adduced  from  other 
groups,  all  going  to  justify  the  empiric  law  formulated  by  Men- 
delejeff,  that  the  properties  oj  the  elements  are  a  periodic  junction 
of  their  atomic  weights  (p.  116).  These  relationships  are  recog- 
nized as  pointing  to  the  conclusion  that  in  the  closely  allied  ele- 
ments of  a  group  there  is  a  common  constituent.  A  more  sweeping 
generalization  is  that  all  the  elements  are  species  or  variations  of 
one  primal  stuff.  They  are  unmistakably  akin,  hence  they 
probably  have  one  common  ancestry. 

SULPHUR    (Brimstone) 

Symbol,  S.     Atomic  weight,  32.06. 

Occurrence. — In  volcanic  regions,  especially  those  of  Sicily, 
this  element  is  found  free  and  almost  pure.  In  considerable 
amounts  it  is  found  in  its  natural  compounds,  the  blendes,  glances, 
pyrites,  and  galena,  in  the  hydrogen  sulphid  of  sulphur  waters, 
and  the  albumin  of  animals. 

Preparation. — Native  sulphur  is  melted  by  setting  fire  to  it, 
and  while  liquid  it  is  run  off  from  the  unfused  minerals  associated 
with  it  into  cylindric  molds.  In  this  form  it  is  called  crude  brim- 
stone. It  is  refined  by  distillation  or  sublimation  and  condensation. 
The  vapor,  received  into  a  cool  chamber,  is  deposited,  first,  as  small 
crystals,  making  the  yellow  powder  known  as  flowers  of  sulphur. 
As  the  chamber  warms,  the  sulphur  condenses  into  a  liquid  at  the 
bottom  and  is  drawn  off  into  molds  to  make  roll  sulphur. 

Physical  Properties.— The  native  element  is  found  as  elon- 
gated octahedral  crystals  of  a  honey-yellow  color,  with  a  very 
faint  taste  and  odor.  Pure  sulphur  may  fail  to  answer  to  the  odor 
test,  but  if  a  small  piece  be  laid  on  polished  silver  it  gives  off  suffi- 
cient vapor  in  a  few  days  to  make  a  brown  halo  of  silver  sulphid. 
The  effect  on  the  silver  accumulates  by  time  until  it  is  perceptible, 
while  that  on  the  sense  of  smell  is  necessarily  transient,  and  not 
intensified  by  time.  It  is  insoluble  in  water,  but  soluble  in  hot 
alcohol,  chloroform,  ether,  carbon  bisulphid,  oils,  and  alkaline 
solutions.  It  melts  at  114°  C.  (237.2°  F.)  to  a  thin  straw-colored 
liquid,  which  becomes  thick  and  brown,  like  molasses,  as  the 
heat  rises  to  160°  C.  (320°  F.);  at  250°  C.  (482°  F.)  it  becomes 
dark  red  and  viscid;  gets  thin  and  yellowish  again  at  340°  C. 
(642°  F.),  until  it  reaches  440°  C.  (824°  F.),  when  it  boils,  emit- 
ting a  brownish  vapor.  These  phenomena  are  remarkable  excep- 


SULPHUR  151 

tions  to  the  rule  that  fluids  become  more  mobile  as  the  internal 
friction  is  lessened  by  the  rise  of  temperature.  On  cooling,  the 
hot  sulphur  passes  through  the  same  stages  in  the  reverse  order, 
solidifying  as  prismatic  crystals. 

Heat  has  a  peculiar  effect  in  changing  the  vapor  density  of 
this  element,  and,  as  the  molecular  weight  is  twice  the  vapor 
density,  we  can  calculate  the  changes  as  variations  in  the  mass  of 
the  molecule.  These  variations  are  due  apparently  to  varying 
mixtures  of  two  allotropic  forms  of  the  element  in  the  state  of 
vapor,  in  one  of  which  there  are  two  atoms  to  the  molecule  S2  and 
the  other  eight  atoms  S8.  The  8-atom  molecule,  S8,  at  440°  C. 
(824°  F.)  dissociates  at  1000°  C.  (1832°  F.)  into  4  diatomic 
molecules  4(S2). 

Amorphous  Sulphur. — If  the  dark  brown  melted  sulphur 
at  or  above  250°  C.  (482°  F.)  be  suddenly  cooled  by  pouring 
it  into  cold  water,  it  becomes  a  soft  tenacious  mass  similar  to 
elastic  rubber.  This  -condition  is  not  permanent,  for  in  some 
hours  it  changes  into  an  opaque  brittle  mass  of  rhombic  octahedra. 
If  crystallization  occurs  at  temperatures  above  100°  C.  (212°  F.), 
the  sulphur  forms  oblique  prisms,  in  no  way  resembling  the  octa- 
hedra. Sulphur  exists  then  in  two  crystalline,  and  one  amorphous, 
varieties. 

Prismatic  or  Monoclinic  Sulphur. — This  is  formed  after  fusion 
and  is  an  amber  yellow,  having  a  specific  gravity  of  1.95,  and 
melting  at  120°  C.  (248°  F.). 

Rhombic  octahedral  sulphur  is  found  in  nature  and  results 
when  sulphur  is  deposited  from  solution  in  carbon  bisulphid.  It 
has  a  specific  gravity  of  2.05  and  melts  at  114-5°  C.  (238°  F.).  On 
exposure  to  the  air  for  several  days  each  monoclinic  prism  ceases 
to  be  transparent  and  splits  into  octahedra. 

Official  Preparations. — Sulphur  sublimatum,  or  flowers  of 
sulphur,  deposited  from  subliming  the  crude  element,  is  an  impure 
preparation  used  externally  in  medicine.  Sulphur  lotum  is  sulphur 
washed  in  water  to  free  it  of  some  of  the  sulphuric  acid  generated 
during  sublimation.  Sulphur  pr&cipitatum,  lac  sulphuris,  milk 
of  sulphur,  is  a  white  powder  so  finely  divided  that  the  yellow  color 
is  lost.  It  is  prepared  by  dissolving  sulphur  in  water  by  means 
of  lime,  and  precipitating  with  hydrochloric  acid.  It  is  the  most 
active  form  for  medicinal  use.  Dose:  \  to  2  dr.  Unguentum 
sulphuris  is  a  15  per  cent,  ointment  used  as  a  parasiticide  in  skin 
diseases. 

Chemical  Properties. — Sulphur,  when  heated,  takes  fire,  burn- 
ing with  a  pale-blue  flame  and  forming  sulphur  dioxid.  As  a  com- 
ponent of  gunpowder  it  generates  the  same  gas.  Sulphur  burns 
in  hydrogen  sulphid.  Like  oxygen,  it  is  at  times  divalent  and  can 


152  NON-METALS 

replace  that  element  to  generate  compounds  resembling  those 
of  oxygen.  To  indicate  this  the  prefix  thio-  is  used  before  the 
name  of  the  oxygen  compound.  Thus,  HOCN  is  cyanic  acid 
and  HSCN  is  thiocyanic  acid. 

Crystallography. — A  solution  of  sodium  chlorid,  like  that 
of  most  solids,  when  evaporated  to  a  thick  fluid  and  set  aside, 
crystallizes — that  is,  the  molecules  of  the  solid  separate  in  reg- 
ular geometric  form.  The  same  phenomenon  is  observed  when 
vapors  of  iodin,  arsenic  trioxid  or  other  substances  solidify.  A 
body  is  called  a  crystal  when  it  has  many  sides  or  plane  surfaces, 
more  or  less  symmetric,  intersecting  at  definite  angles.  That 
there  is  an  internal  structure  is  shown  by  a  tendency  to  break  with 
planes  of  cleavage  corresponding  to  the  external  surface  planes. 
A  well-known  example  is  mica.  Crystals  transmit  heat,  light,  and 
electricity  differently  in  different  directions,  owing  to  this  peculiar 
arrangement  of  their  deep-seated  parts.  Perfect  crystals  are  rare, 
because  the  conditions  are  seldom  ideal.  Before  the  shape  is 
symmetrically  developed  another  crystal  may  separate  which  is 
superimposed  and,  therefore,  impedes  the  growth  of  the  first 
formed.  Still,  as  the  angles  are  well  defined  and  the  relationship 
of  the  faces  preserved,  these  constants  are  sufficient  data  for 
geometry  to  construct  the  ideal  form  of  the  crystal.  There  are 
substances,  like  gum,  resin,  and  glass,  which  never  show  geometric 
structure,  and  are,  therefore,  called  amorphous,  or  formless.  These 
do  not  break  in  planes  of  cleavage,  but  conduct  heat  and  electricity 
and  transmit  light  equally  well  in  all  directions. 

The  crystalline  form  is  a  very  definite  property  which  forces 
itself  upon  our  observation  and  is  as  characteristic  as  the  points 
of  freezing  and  boiling.  It  is  a  valuable  means  of  identification, 
and  is,  therefore,  classed  among  the  significant  characters  of  a 
substance. 

The  manifold  external  shapes  of  crystals  can  all  be  referred  to 
one  of  six  systems  characterized  by  their  imaginary  axes  and  planes 
of  symmetry. 

i.  The  regular  system  includes  crystals  with  three  equal  imag- 
inary axes  crossing  in  the  center  at  right  angles  to  each  other. 
The  simplest  form  is  the  cube  (Fig.  42)  with  the  axes  terminating 
in  the  center  of  the  surfaces.  (Examples:  sodium  chlorid  and 
other  haloid  salts.)  If  the  solid  angles  of  the  cube  be  cut  off,  the 
law  of  its  symmetry  is  preserved  and  a  secondary  form  appears,  the 
right  octahedron  (Fig.  45).  (Examples:  diamond,  alum,  arsenic 
trioxid.)  By  cutting  off  the  edges  of  the  octahedron  and  cube 
symmetrically  the  third  derivative  is  obtained,  the  rhombic  dodeca- 
hedron (Fig.  43).  (Example:  garnet.)  The  regular  tetrahedron 
(Fig.  44)  is  obtained  by  cutting  off  the  alternate  solid  angles  of  the 


CRYSTALLOGRAPHY 


cube  or  extending  the  alternate  faces  of  the  octahedron  (Fig.  44). 
(Example:  boracite.) 


FIG.  42. — Cube. 


FIG.  43. — Dodecahedron. 


FIG.  44. — Tetrahedron  developed 
from  octahedron. 


2.   The  quadratic  system  includes  crystals  with  three  axes  inter- 
secting  at   right   angles,   two   of  which   are   of  equal   length,   the 
third  differing  and  being  called  the  prin- 
cipal  axis.     The   simple   forms   are   the 
right   square-based   octahedron    (Fig.    45) 
and  the  right-square  prism  with  a  termi- 
nal plane  at  right  angles  to  the  principal 


FIG.  45. — Quadratic  octahedron. 


FIG.  46.— Quadratic  prism 
with  pyramidal  end. 


axis,    or    with    terminal    pyramids    (Fig.    46). 
sium  ferrocyanid.) 


(Example:  potas- 


FIG.  47. — Double  six-sided 
pyramid. 


FIG.  48. — Hexagonal 
prism. 


FIG.  49. — Rhombohedron. 


3.  The  hexagonal  system  contains  the  forms  referred  to  four 
axes,  three  of  equal  length,  inclined  to  60°  to  each  other,  and  the 
fourth,  of  any  length,  at  right  angles  to  the  other  three.  The 
fundamental  form  is  the  double  six-sided  pyramid  (Fig.  47). 


NON-METALS 


Another  form  is  the  hexagonal  prism  which,  combined  with  the 
pyramids,  gives  the  shape  of  the  quartz  crystal  (Fig.  48).  By 
developing  the  alternate  faces  of  the  double  pyramid  the  rhombo- 
hedron  is  formed  (Fig.  49),  as  in  calcite  or  Iceland  spar.  (Exam- 
ple: ice.) 

4.  The  orthorhombic  system  includes  crystals  that  have  three 
axes  of  unequal  length  intersecting  at  right  angles  to  each  other. 
The  principal  forms  are  the  right  octahedron  or  double  jour-sided 
pyramid  with  rhombic  base  (Fig.  51)  and  the  right  rhombic  prism. 
(Examples:  native  sulphur  and  niter.) 

5.  The  monoclinic  and  oblique  system  contains  the  crystals 
that  can  be  referred  to  three  axes,  of  equal  or  unequal  length,  two 
of  them  at  acute  angles,  and  the  third  at  right  angles  to  the  other  two. 
The  fundamental  form  is  a  double  pyramid  with  an  inclined  axis 
and  a  rhombic  base  (Fig.  50).      Examples:  sulphur  from  fusion, 
ferrous  sulphate,  sodium  carbonate,  cane-sugar.) 


FIG.  50. — Monoclinic 
octahedron. 


FIG.  51. — Orthorhombic 
octahedron. 


FIG.  52.— Triclinic 
octahedron. 


6.  The  triclinic  system  groups  together  the  crystals  which  can 
be  referred  to  three  axes,  all  inclined  to  one  another  at  angles, 
not  right  angles.  These  crystals  are  the  least  symmetric,  for 
only  the  parallel  and  opposite  faces  are  equal,  as  in  the  doubly 
oblique  octahedron  (Fig.  52).  (Examples:  potassium  bichromate, 
copper  sulphate.) 

When  a  substance  has  two  definite  forms,  like  sulphur,  it  is 
said  to  be  dimorphous.  These  forms  are  found  to  differ  in  their 
specific  gravities  and  other  properties.  Very  rarely  instances 
occur  of  the  same  substance  forming  crystals  referable  to  three 
different  systems;  such  substances  are  said  to  be  trimorphous. 
There  are  many  substances  of  different  composition  which  crys- 
tallize in  the  same  forms,  and  hence  are  said  to  be  isomorphous. 
Among  these  there  often  exists  a  certain  correspondence  in  the 
constitution  of  the  molecules,  as  in  the  class  of  salts  of  different 
metals  known  as  alums,  so-called  from  their  resemblance  to  the 
•type,  common  alum. 

Hydrogen     Sulphid     (H2S)     (Sulphydric    Acid,     Sulphureted 


SULPHUR 


Hydrogen). — Occurrence. — Mineral  springs  of  the  class  known  as 
sulphur  waters  contain  this  gas.  It  is  a  product  of  the  putre- 
factive fermentation  of  proteid  substances,  and  hence  is  found  in 
foul  abscesses  and  in  small  amounts  in  the  flatus  of  the  intestines. 

Preparation. — The  most  convenient  method  of  preparation, 
and  the  one  generally  used,  is  that  consisting  in  the  action  of 
dilute  sulphuric  acid  on  ferrous  sulphid.  Hydrochloric  acid  and 
antimony  sulphid  may  also  be  used.  In  coarse  pieces  the  ferrous 
sulphid  is  put  into  the  usual  hydrogen-generating  flask  (Fig.  28) 
and  sulphuric  or  hydrochloric  acid  in  the  proportion  of  i  :  6  of  water 
is  added  as  required.  A  wash-bottle  containing  water  is  attached 
to  remove  impurities.  Kipp's  apparatus  (Fig.  53)  is  a  convenient 


FIG.  53.— Kipp's  apparatus  for  hydrogen  sulphid,  with  wash-bottles  attached. 

source  of  the  gas  in  a  regulated  supply.  It  has  three  vessels 
superposed;  in  a  is  the  dilute  sulphuric  acid  which  is  fed  from  c. 
It  rises  until  it  acts  on  the  ferrous  sulphid  in  the  generator  b;  the 
gas  confined  presses  out  the  acid,  which  then  rises  to  c,  and  action 
ceases  until  the  gas  is  allowed  to  escape  at  the  cock,  when  the 
acid  descends  to  its  first  position.  The  gas  is  washed  in  d,  and 
acts  on  the  metallic  solution  in  e. 


FeS 

Ferrous  sulphid. 

FeS 


H2S04 

Sulphuric  acid. 

2HC1 


FeSO4 

Ferrous  sulphate. 

FeCl2 

Ferrous  chlorid. 


H2S 

Hydrogen  sulphid. 

H2S. 


Physical  Properties. — Hydrogen  sulphid  is  a  gas  without  color, 
but  having  the  disgusting  odor  and  taste  of  rotten  eggs.     It  is 


156  NON-METALS 

slightly  heavier  than  the  air;  specific  gravity  1.19.  At  —74°  C. 
(-101.2°  F.)  it  liquefies,  and  at  -85.5°  C.  (-122°  F.)  it  freezes 
into  white  crystals.  One  volume  of  water  absorbs  three  of  this 
gas  to  form  a  colorless  solution  having  the  odor  and  chemical 
powers  of  the  gas  itself.  On  boiling,  all  the  gas  is  expelled.  While 
this  solution  is  useful  in  the  laboratory,  it  is  not  stable,  soon  taking 
oxygen  from  the  air  to  form  water  with  the  deposit  of  sulphur.  To 
prevent  this  deterioration  the  water  should  first  be  boiled  to  expel 
the  dissolved  oxygen,  and  the  solution  then  kept  in  well-filled  and 
well-stoppered  bottles.  This  solution  is  sometimes  called  sul- 
phydric  acid.  With  ammonia  it  forms  two  compounds,  ammonium 
sulphid,  (NH4)2S,  and  ammonium  sulphydrate,  (NH4)HS. 

Chemical  Properties. — If  delivered  at  a  jet,  hydrogen  sulphid 
burns  with  a  blue  flame,  forming  sulphur  dioxid  and  water: 

H2S          +          30  SO2          +          H2O. 

An  explosive  mixture  results  when  air  is  added  to  hydrogen 
sulphid.  Soluble  sulphydrates  or  hydrosulphids  are  produced  by 
passing  it  into  a  solution  of  an  alkaline  hydroxid: 

KHO          +          H2S  H2O          +          KHS. 

Potassium  hydroxid.  Potassium  hydrosulphid. 

As  a  Group  Reagent. — Solutions  of  the  heavy  metals  (p.  210), 
when, charged  with  hydrogen  sulphid  yield  sulphids  and  the  acid 
of  the  salt  is  set  free: 

CuSO4         +       *H2S  CuS         +         H2SO4. 

Copper  sulphate.  Copper  sulphid.  Sulphuric  acid. 

The  copper  sulphid  is  thrown  down  as  a  brownish-black  pre- 
cipitate. With  zinc  sulphate  a  scanty  white  precipitate  of  zinc 
sulphid  is  produced  according  to  the  equation: 

ZnS04         +         H2S  ZnS         +         H2SO4. 

Even  with  excess  of  H2S  all  the  zinc  is  not  precipitated,  but  some 
of  its  sulphid  remains  in  solution.  The  addition  of  potassium 
hydroxid  by  removing  the  free  H2SO4,  causes  a  further  precipitate 
of  ZnS.  If  this  ZnS  be  collected  on  a  filter  and  treated  in  a  test- 
tube  with  sulphuric  acid,  H2S  is  liberated  by  a  reaction,  the  reverse 
of  that  given  above.  This  reversible  character  is  shown  in  the 
equation 

ZnS         +         H2SO4        ^±        ZnSO4         +         H2S. 


SULPHUR  157 

The  movement  may  be  in  either  direction  according  to  which 
side  is  in  the  ascendant  by  its  concentration.  Much  H2S  +  ZnSO4  in 
the  solution  causes  the  formation  of  ZnS  +  H2SO4,  whereas  a  large 
amount  of  H2SO4  carries  the  action  toward  the  formation  of  ZnSO4 
+  H2S.  This  is  a  notable  illustration  of  the  effect  of  mass  and  of 
the  rule  that  the  operation  of  every  reaction  is  limited  according 
to  the  products  present. 

The  different  metallic  sulphids  behave  differently  to  weak  acids: 
When  insoluble  in  acids  (as  is  the  case  with  sulphids  of  Pb,  Bi,  Ag, 
Hg,  Cu,  Cd,  As,  Sb,  Au,  Pt,  Sn)  there  is  a  precipitate  with  hydrogen 
sulphid;  when  soluble  in  the  acids  (as  is  the  case  with  sulphids  of  Fe, 
Co,  Ni,  Mn,  Zn,  Th,  Ur)  an  alkali  solution  with  the  hydrogen  sul- 
phid precipitates  them.  This  latter  class  is  more  conveniently 
precipitated  by  adding  an  alkaline  sulphid  or  ammonium  sulphid: 

ZnCl2         +          (NH4)2S  ZnS          +          2NH4C1 

Zinc  chlorid.  Ammonium  sulphid.  Zinc  sulphid.  Ammonium  chlorid. 

The  metals  of  the  alkalies  and  alkaline  earths  form  with  hydro- 
gen sulphid  soluble  sulphids  and  make  the  analytic  group  of  metals 
not  precipitated  by  hydrogen  sulphid  or  by  ammonium  sulphid. 

Toxicology. — If  inhaled  pure,  this  gas  is  immediately  fatal,  and 
even  when  diluted  to  i  per  cent,  it  kills,  though  more  slowly/ 
As  a  constituent  of  the  gas  of  privies,  burial  vaults,  sewers,  and 
the  slag  heaps  of  chemical  works  its  minor  toxic  symptoms  are 
often  seen.  They  are  nausea,  vomiting,  depression,  giddiness, 
headache,  labored  breathing,  stupor,  and  coma.  In  laboratories 
it  should  not  be  used  outside  the  fume  chamber.  The  air  con- 
taminated with  it  acts  as  an  insidious  poison,  partly  by  its  power 
of  reducing  the  hemoglobin  of  the  blood-corpuscles,  but  mainly 
as  a  direct  paralyzer  of  the  nerve  centers  of  the  lungs  and  heart. 

Postmortem  Appearances. — The  blood  is  liquid  and  dark  brown 
in  color,  from  the  sulphid  of  iron  formed  with  the  red  coloring- 
matter.  A  silver  coin  inserted  into  an  incision  blackens,  even 
before  putrefaction  sets  in. 

Treatment  consists  in  prompt  removal  to  pure  air,  artificial 
respiration,  inhalations  of  oxygen,  warmth  to  the  extremities,  and 
stimulants. 

Detection. — The  odor  is  perceptible  when  i  part  is  present  in 
10,000  of  air.  This  may  be  confirmed  by  exposing  a  piece  of 
white  filter-paper  soaked  in  solution  of  lead  acetate;  it  blackens. 

Sulphur  Dioxid  (SO2)  (Sulphurous  Anhydrid}.— Preparation. 
— When  sulphur  is  burned  in  oxygen  or  in  the  air,  direct  union 
occurs:  S-fO2  =  SO2.  This  method  for  the  generation  of  sul- 
phur dioxid  is  used  for  the  disinfection  of  rooms.  Sulphur  dioxid 
is  formed  when  certain  sulphids,  like  pyrites,  FeS2,  are  roasted  in 


158  NON-METALS 

the  air,  as  in  the  first  step  in  the  manufacture  of  sulphuric  acid. 
One  method  of  extemporaneous  generation  without  heat  con- 
venient for  the  laboratory  is  to  have  on  hand  a  solution  of  sodium 
bisulphite  made  from  that  salt  or  prepared  by  charging  a  solution 
of  sodium  carbonate  with  sulphur  dioxid.  This  solution  is 
placed  in  a  tap-funnel  of  the  apparatus  Fig.  37.  In  the  flask  is 
concentrated  sulphuric  acid.  On  opening  the  cock,  the  bisulphite 
solution  drops  into  the  acid  and  SO2  is  set  free  at  any  desired  rate. 

NaHSO3   +   H2SO4   =   NaHSO4   +   H2O   +   SO2. 

Sodium  bisulphite.  Sodium  bisulphate. 

The  usual  laboratory  method  is  by  heating  strong  sulphuric 
acid  with  copper  in  a  flask  seen  in  Fig.  41:  2H2SO4+ Cu=  CuSO4 
+  2H2O  +  SO2.  Owing  to  its  solubility  in  water  the  pneumatic 
trough  is  not  used,  but  the  gas  is  collected  in  upright  jars  with 
glass  stoppers  greased  with  vaselin. 

Physical  Properties. — Sulphur  dioxid  is  a  colorless  gas  with  a 
stifling  odor  and  a  persistent  taste,  familiar  in  the  odor  and  taste 
of  the  smoke  of  sulphur  matches.  Its  specific  gravity  is  2.23; 
hence,  it  may  be  collected  by  downward  displacement.  At  room 
temperature  it  is  readily  liquefied  under  three  atmospheres  of 
pressure,  or  under  ordinary  pressure  if  cooled  artificially  by  a 
mixture  of  ice  and  salt  to— 10°  C.  (14°  F.).  It  freezes  at  —75° 
C.  (—103°  F.).  Compressed  in  siphons,  sealed  cans,  or  steel 
cylinders  it  is  a  market  product. 

Chemical  Properties. — Sulphur  dioxid  does  not  burn  nor  will 
it  support  combustion.  If  a  handful  of  flowers  of  sulphur  be 
thrown  down  a  burning  chimney  the  fire  will  be  extinguished. 
The  sulphur  takes  fire  and  yields  SO2,  which  smothers  the  flames. 
When  SO2  is  passed  into  solutions  of  metallic  hydroxids  it  forms 
sulphites  or  bisulphites,  according  to  the  amount  of  hydrogen 
replaced. 

Acidum  Sulphurosum. — Water  dissolves  about  50  times  its  vol- 
ume of  the  gas  at  ordinary  temperatures,  resulting  in  the  official 
sulphurous  acid,  H2SO3  (Fig.  41).  After  a  bottle  is  filled  with 
gas  if  a  little  water  be  added  and  the  bottle  closed  and  shaken,  on 
opening  again  the  air  rushes  in  to  take  the  place  of  the  gas  absorbed 
by  the  water.  A  test-tube  filled  with  dry  SO2  and  inverted  with 
the  mouth  under  water  slowly  fills  with  water.  It  is  a  colorless 
liquid  with  an  acid  reaction  first  reddening  litmus  and  afterward 
bleaching  it,  and  forms  two  classes  of  salts  represented  by  sodium 
sulphite,  Na2SO3,  in  which  sulphosion  (SO3)"  is  divalent,  and 
sodium  bisulphite,  NaHSO3,  containing  univalent  hydrosulphosion 
(HSO3)'.  It  is  a  weak  acid,  decomposing  by  heat  into  H2O-f 
SO2.  Sunlight  causes  rapid  deterioration  by  oxidation. 


SULPHUR  159 

The  moist  gas  and  even  more,  the  acid  solution,  are  characterized 
by  their  readiness  to  take  one  more  atom  of  oxygen  from  sub- 
stances rich  in  that  element.  They  are,  therefore,  called  powerful 
reducing  agents,  being  converted  themselves  into  a  higher  oxygen 
compound,  sulphuric  acid: 

SO2       +       H2O        +       O  H2SO4. 

A  striking  exhibition  of  this  reducing  property  is  seen  when 
the  purple  solution  of  potassium  permanganate  is  added  to  sul- 
phurous acid.  The  color  is  discharged,  due  to  the  yielding  of 
oxygen  to  the  H2SO3,  which  becomes  H2SO4.  Sulphur  dioxid  is 
also  a  bleaching  agent,  taking  oxygen  from  vegetable  dyes.  This 
may  be  shown  by  burning  sulphur  near  moist  flowers  under  a 
bell  jar.  The  flowers  lose  their  color,  which,  however,  can  be 
partly  restored  by  immersion  in  weak  sulphuric  acid. 

With  powerful  reducing  agents  the  gas  may  give  up  its  oxygen, 
thus  becoming  an  oxidizing  agent: 

4S02     +     3H2S  2H20     +     H2S506     +     S2. 

Hydrogen  sulphid.  Pentathionic  acid. 

Medical  Uses. — Sulphur  dioxid  is  very  destructive  to  plant 
life,  high  and  low.  A  few  pounds  of  sulphur  burned  in  a  mouldy 
cellar  or  conservatory  causes  the  minute  fungi  to  disappear. 
This  property  makes  it  valuable  as  an  aerial  disinfectant  and 
vermin-killer.  For  every  1000  cu.  ft.  4  pounds  of  sulphur  must 
be  burned.  The  sulphur  candle  may  be  used,  or  a  mixture  of 
flowers  of  sulphur  and  turpentine  may  be  fired,  if  supported 
by  bricks  in  a  washtub  containing  water.  As  the  gas  is  irre- 
spirable,  the  combustion  cannot  be  watched.  The  room  must 
be  kept  tightly  closed  for  twenty-four  hours,  and  then  aired 
before  being  occupied.  All  bugs,  fleas,  mosquitoes,  and  many 
bacteria  are  destroyed  by  this  means.  Many  fabrics  left  in  such 
an  atmosphere  are  bleached,  and  perishable  foods,  such  as  meats 
and  fruit,  are  made  preservable  for  days.  This  preservative 
property  is  shared  by  its  salts,  the  sulphites  and  bisulphites,  which 
are  often  dusted  over  meats  to  prevent  decay.  Digestion  of 
foods  so  preserved  is  retarded  because  the  antiferments  interfere 
with  the  activity  of  the  enzymes  of  digestion.  Sulphurous  acid  and 
the  sulphites  are  prohibited  by  U.  S.  law  (1908)  as  preservatives 
of  food.  Sulphur  dioxid  is  not  condemned  when  used  in  fumi- 
gating wines,  dried  fruits,  or  sugars  to  the  extent  of  350  mg.  per 
kilogram  left  in  the  product.  In  these  cases  a  certain  amount 
combines  with  aldehyd  and  sugar  to  make  harmless  compounds, 
but  any  excess  is  toxic.  Acid-urn  sulphurosum  is  a  parasiticide 


l6o  NON-METALS 

for  skin  diseases.  It  is  given  internally  to  check  gastric  fermenta- 
tions. Dose:  f3ss-j  (2-4  c.c.),  largely  diluted. 

Tests. — The  stifling  odor  of  burning  sulphur  matches  is  char- 
acteristic of  sulphur  dioxid.  Starch-paper  moistened  with  a  solu- 
tion of  iodic  acid  turns  blue  when  exposed  to  air  containing  i  part 
of  SO2  in  3000. 

Sulphur  Trioxid  (SO3)  (Sulphuric  Anhydrid). — Preparation. 
— In  burning  sulphur  most  of  it  becomes  SO2,  but  a  small  quan- 
tity of  misty  substance  is  formed  which  has  the  formula  SO3. 
When  fuming  sulphuric  acid  is  heated  it  decomposes  with  the 
production  of  SO3. 

H2S207  H2S04          +          S03. 

Pyrosulphuric  acid.  Sulphuric  acid.  Sulphur  trioxid. 

Properties. — Sulphur  trioxid  is  a  transparent  colorless  liquid 
which  freezes  at  16°  C.  (60.8°  F.)  to  a  white  solid.  After  being 
kept  awhile  a  modified  form  is  produced  at  ordinary  temperature, 
forming  white  asbestos-like  crystals.  This  white  solid  dissolves 
in  water  with  a  crackling  sound,  resulting  in  H2SO4  and  evolving 
much  heat.  It  is  used  by  dyers  as  an  oxidizing  agent. 

Sulphuric  Acid  (H2SO4)  (Oil  of  Vitriol).— Occurrence.— In 
almost  every  technical  process  this  acid  is  used  at  one  stage  or 
another.  Its  manufacture  is  of  supreme  importance  in  the  arts, 
and  illustrates  some  most  interesting  reactions. 

Preparation. — Under  the  demand  for  sulphur  trioxid  in  the 
manufacture  of  artificial  indigo  the  catalytic  method  has  been 
brought  to  a  point  of  practical  efficiency  and  economy.  The 
theory  is  simplicity  itself:  By  heating  in  the  air  ores  of  sulphur 
and  iron  (pyrites)  SO2  is  formed.  This  is  purified,  cooled,  and 
with  the  oxygen  of  the  air  passed  through  cylinders  containing 
heated  plates  holding  a  mixture  of  finely  divided  platinum  and 
asbestos.  The  SO2  unites  directly  with  O  to  form  SO3,  which  is 
dissolved  in  some  weak  sulphuric  acid.  It  can  be  obtained  of  any 
desired  strength  from  the  ordinary  sulphuric  acid  to  the  fuming 
article.  Any  arsenic  in  the  SO2  soon  stops  the  action  of  the 
platinum;  hence  it  is  removed  before  the  gas  enters  the  cylinder. 
This  insures  a  product  which  is  arsenic  free.  As  the  platinum 
does  not  enter  into  the  reaction,  a  small  amount  serves  to  oxidize  very 
large  quantities  of  the  SO2.  It  appears  that  a  union  which  goes 
on  very  slowly  between  SO2  and  oxygen  at  all  times  is  hastened 
to  a  high  degree  by  catalysis,  due  to  platinum,  which  facilitates  the 
motion  much  as  a  lubricant  does  in  machinery. 

Lead-chamber  Process. — This  process  can  be  illustrated  simply 
by  immersing  in  a  vessel  containing  SO2  a  sliver  of  wood  wet 
with  nitric  acid.  Red  fumes  of  N2O4  arise,  which  change  to  color- 


SULPHURIC    ACID  l6l 

less  N2O2  when  the  vessel  is  closed.  Again  opening  the  vessel, 
air  enters  and  N2O2  forms  red  fumes  of  N2O4.  Eventually  crystals 
of  nitryl-sulphuric  acid  appear  inside  the  glass  and  these  are 
washed  down  with  water  to  form  impure  H2SO4.  The  H2SO4 
can  be  identified  by  evaporating  with  powdered  sugar  in  a  por- 
celain dish  over  a  water-bath.  The  residue  turns  brown  and  then 
black.  Until  recently  this  was  the  most  accepted  method  of 
manufacture.  It  is  based  on  the  principle  of  burning  S  to  SO2, 
mixing  the  gas  with  H2O  and  O  of  the  air,  and  accelerating  their 
union  by  the  aid  of  nitric  acid  and  nitrogen  oxid.  Thus: 

(1)  2HN03  +  S02  H2S04      +       N204. 

(2)  2SO2  +  N3O4  =       2SO3         +       N2O2. 

(3)  S03  +  H20  H2S04. 

(4)  N20a  +  02  N204. 

These  equations  show  how  the  nitrogen  oxids  act  as  go-betweens, 
taking  up  oxygen  from  the  air  and  turning  it  over  to  the  sulphur 
dioxid.  The  sulphur  trioxid  then  joins  with  water  to  make 
sulphuric  acid.  The  gases  are  mixed  in  a  series  of  lead-lined 
chambers. 

The  lead  lining  resists  the  action  of  sulphuric  acid  until  it  gets 
to  80  per  cent.  acid.  When  further  concentration  is  desired, 
this  acid  is  evaporated  in  flat  platinum  stills. 

Impurities  oj  the  crude  acid  are  due,  first,  to  the  arsenic  com- 
pounds volatilized  from  the  roasting  ore;  second,  to  the  lead 
sulphate  formed  in  the  chambers;  third,  to  the  nitro  compounds 
still  retained;  fourth,  to  particles  of  straw  and  organic  dust  which 
give  it  a  brownish  color.  The  acid  is  purified  by  distillation. 

Properties. — Pure,  strong  sulphuric  acid  (acidum  sulphuricum, 
U.  S.)  of  a  specific  gravity  not  below  1.826  contains  not  less  than 
92.5  per  cent,  of  real  acid  (H2SO4),  and  is  a  colorless,  heavy,  oily 
liquid,  not  fuming,  odorless,  extremely  sour,  combining  actively 
with  water,  and  blackening  or  charring  organic  substances.  It 
crystallizes  at  10.5°  C.  (50.9°  F.),  and  boils  at  338°  C.  (640.4°  F.). 
The  commercial  oil  of  vitriol  is  colored  light  brown  by  suspended 
carbonaceous  matter  and  contains  small  amounts  of  dissolved 
metals,  principally  lead  and  arsenic.  When  added  to  water,  heat 
is  given  out.  If  the  proportion  of  the  mixture  be  3  of  acid  to  i  of 
water,  the  temperature  will  rise  above  100°  C.  (212°  F.).  It 
has  the  property  of  abstracting  water  from  the  air,  100  gr.  under 
favorable  conditions  absorbing  120  gr.  of  water  in  four  days; 
hence  its  use  in  desiccators  for  drying  precipitates  on  filter  papers. 
One  of  the  best  methods  of  drying  gases  is  by  passing  them  through 


162  NON-METALS 

concentrated  sulphuric  acid.  This  great  affinity  for  water  explains 
the  charring  action  upon  organic  matter  such  as  cane-sugar,  paper, 
etc.,  from  which  it  abstracts  the  elements  of  water  while  dissolving 
all  but  the  black  carbon.  When  the  concentrated  acid  is  heated 
with  zinc,  copper,  or  other  metals,  the  gas  sulphur  dioxid  is  lib- 
erated; if  the  acid  be  dilute,  then,  if  any  action  occurs,  the  gas 
evolved  is  hydrogen. 

Nordhausen  acid  is  a  form  manufactured  in  Bohemia  and  used 
largely  in  chemical  industries.  It  is  a  dark-brown,  heavy,  oily, 
fuming  liquid,  with  a  specific  gravity  of  1.9.  Its  formula  is 
H2S2O7,  and  it  is  regarded  by  some  as  a  solution  of  SO3  in  H2SO4. 
Two  weaker  forms  are  used  in  medicine,  the  dilute  (acidum  sul- 
phuricum  dilutum,  U.  S.),  of  10  per  cent.  H2SO4,  and  the  aromatic 
(acidum  sulphuricum  aromaticum,  U.  S.),  of  20  per  cent.  H2SO4. 
Dose,  10  to  20  Tit  (0.66-1.23  c.c.). 

Medical  Uses. — The  concentrated  acid  is  applied  externally  as 
a  powerful  caustic  in  the  shape  of  Ricord's  paste,  made  with 
powdered  charcoal,  and  Michel's  paste,  made  with  powdered 
asbestos. 

The  dilute  forms  only  are  used  internally  as  solvents  for  quinin 
and  as  a  remedy  for  night-sweats. 

Its  incompatibles  are  the  alkalies;  alcohol;  salts  of  barium, 
calcium,  strontium,  lead,  mercury,  and  silver;  sulphids. 

Monobasic  and  Dibasic  Acids. — The  halogen  acids  have  but 
one  combining  weight  or  atom  of  hydrogen,  as  HC1,  but  the  three 
sulphur  acids  already  referred  to,  H,S,  H2SO3,  and  H2SO4,  have  two, 
both  of  which  are  replaceable  by  metals.  With  a  bivalent  metal, 
like  calcium,  but  one  salt  is  formed,  by  H2SO4;  *.  e.,  CaSO4,  the 
calcium  replacing  both  hydrogen  atoms.  As  one  or  both  of  these 
hydrogen  atoms  may  be  replaced  by  a  univalent  metal,  two  different 
salts  are  conceivable.  For  example,  with  sodium  there  are  two 
possible  reactions: 

H2S04      +     NaHO       =       NaHSO4      +     H2O; 
and 

H2S04      +      2NaHO      =        Na2SO4        +      2H2O. 

Acids,  like  hydrochloric,  which  have  but  one  replaceable 
hydrogen  atom  and  which,  therefore,  react  with  only  one  com- 
bining weight  of  a  base  to  form  but  one  salt,  as  Nad,  are  called 
monobasic. 

Acids,  like  sulphurous  and  sulphuric,  which  react  either  with  one 
or  with  two  combining  weights  of  a  base,  are  called  dibasic.  They 
have,  as  a  rule,  but  two  atoms  of  replaceable  hydrogen,  and  when 
these  are  both  replaced  by  a  metal  the  >  salt  is  called  neutral  or 
normal.  Salts  of  dibasic  acids  which  have  one  atom  of  metal 


SULPHURIC    ACID  163 

retaining  one  of  hydrogen,  which  is  the  characteristic  component 
of  acids,  are  called  acid  salts.  Sometimes  the  two  salts  are  desig- 
nated by  the  prefixes  mono-  and  di-  to  the  name  of  the  metal,  as 
NaHSO4,  monosodium  sulphate;  Na2SO4,  disodium  sulphate. 
Again,  they  are  called  primary  and  secondary.  Sometimes  they 
are  distinguished  by  calling  the  normal  salt  Na2SO4,  sodium 
sulphate;  and  the  acid  salt  NaHSO4,  bisulphate. 

Dissociation  of  a  Dibasic  Acid.— Sulphuric  acid  forms  two 
kinds  of  anions:  (i)  In  concentrated  solution  the  univalent 
hydrosulphanion  (HSO4)'  predominates:  H2SO4  =  H',(HSO4)'; 
(2)  when  diluted  this  breaks  down  and  dissociates  into  2H*  and 
the  bivalent  sulphanion  (SO4)".  When  the  dilution  is  sufficient 
there  is  complete  dissociation:  H2SO4  =  H-,H',(SO4)".  If  an  acid  is 
weak,  like  carbonic  acid,  H2CO3,  stage  (i)  prevails  through  all 
dilutions,  the  second  hydrogen  ion  dissociating  to  only  a  slight 
degree.  The  solution  of  its  acid  salt,  MHA  (where  M  is  any 
univalent  metal  and  A  a  dibasic  acid),  forms  the  ions  M*  and 
(HA)',  the  group  (HA)'  scarcely  breaking  up  at  all.  As  there  is 
little  or  no  hydrion,  there  is  a  very  slight  acid  reaction,  and  the 
so-called  acid  salt  behaves  like  a  neutral  salt;  it  may  even  be 
alkaline  in  reaction,  as  is  sodium  bicarbonate,  NaHCO3.  When 
the  acid  is  strong,  like  sulphuric  acid,  dissociation  is  probably 
complete  into  H*,H*  and  A".  On  dissolving  its  acid  salt  MHA 
the  (HA)7  at  first  formed  undergoes  further  dissociation  into  the 
ions  H*  and  A",  and  the  solution  finally  contains  the  three  ions, 
H*,  in  relatively  large  amount,  M*,  and  A".  The  abundant 
hydrion  gives  it  the  properties  of  an  acid. 

Toxicology. — As  there  are  few  processes  in  the  arts  that  do  not 
use  at  some  stage  the  oil  of  vitriol  it  can  be  had  at  any  chemist's. 
It  is  used  for  cleansing  metals  as  a  household  article.  In  countries 
where  the  law  makes  it  difficult  to  purchase  the  arsenic  or  alka- 
Icidal  poisons  the  ease  with  which  sulphuric  acid  can  be  procured 
makes  it  a  very  common  poison  in  use  by  the  poorer  classes  for 
suicidal  purposes.  It  is  rarely  given  in  food  for  homicidal  pur- 
poses, because  it  betrays  the  poisoner  by  the  altered  appearance 
of  the  charred  food,  by  the  stains  on  the  clothing,  lips,  and  tongue, 
by  the  fiery  taste,  and  by  the  characteristic  symptoms.  It  has 
been  given  to  young  children  and  even  to  adults  in  the  form  of 
medicine,  taken,  as  disagreeable  doses  usually  are,  from  a  spoon 
back  of  the  tongue,  so  as  to  avoid  tasting. 

Poisoning  has  occurred  from  the  accidental  substitution  of 
sulphuric  acid  for  oils,  syrup,  or  glycerin.  It  has  been  poured 
into  the  ear,  given  by  enema,  and  even  injected  into  the  vagina. 

Local  External  Effects. — Malicious  persons  resort  to  sulphuric 
acid  to  disfigure  the  face  or  ruin  the  clothes  by  throwing  a  quantity 


164  NON-METALS 

of  it  at  the  hated  person.  Occasionally  in  chemical  laboratories, 
while  experimenting  with  it,  flasks  containing  it  will  burst  and  the 
contents  be  dashed  into  the  face  of  the  experimenter.  If  it  strike 
the  eye,  blindness  may  result.  In  contact  with  the  skin  it  causes 
great  agony  and  a  lasting  scar.  Instant  action  is  necessary  to 
prevent  these  serious  effects.  Water  must  be  applied  freely,  the 
whole  face  immersed  in  a  basin  of  it  or  held  under  a  running  tap, 
and  the  eyes  opened  under  the  water.  A  paste  of  sodium  bicar- 
bonate or  a  piece  of  soap  will  help  to  neutralize  the  residual  acid 
at  the  burned  points.  The  burn  may  be  treated  afterward  with 
linimentum  colds.  It  is  a  common  accident  in  the  laboratory  for 
the  acid  to  fall  upon  the  clothing.  If  not  promptly  touched  with 
ammonia  or  some  alkaline  solution,  the  spot  turns  red  and  soon 
becomes  rotten. 

Symptoms. — On  the  instant  of  contact  with  the  mouth  there  is 
intense  pain,  extending  down  the  throat  and  gullet  to  the  pit  of 
the  stomach,  along  the  track  of  the  acid.  The  tongue  swells  until 
it  fills  the  mouth,  and  is  covered  with  a  white  coating;  later,  it 
may  be  a  corroded  and  shapeless  mass. 

The  saliva  flows  profusely,  but  cannot  be  swallowed  without 
pain,  owing  to  the  pharyngeal  inflammation.  Gasping  and 
a  hoarse  voice  denote  that  some  of  the  acid  has  touched  the  larynx 
and  caused  spasmodic  closure  of  the  glottis. 

The  thirst  is  extreme,  and  is  accompanied  by  persistent  retching 
and  vomiting.  The  ejected  matter  is  very  sour  and  slimy,  often 
bloody,  and  loaded  with  portions  of  the  mucous  membrane  of 
the  gullet  and  stomach.  The  face  has  an  agonized  expression, 
the  eyes  look  hollow,  the  nose  is  pinched  and  cold,  the  skin  clammy, 
the  pulse  feeble,  the  breathing  difficult,  and  the  extremities  are 
convulsed.  The  case  may  end  fatally  in  a  few  hours  or  after 
several  days  by  asphyxia,  stupor,  or  convulsions.  When  per- 
foration of  the  stomach  is  caused  by  rapid  solution  of  its  walls, 
the  symptoms  of  fatal  collapse  rapidly  develop  and  death  is  com- 
paratively painless.  When  death  is  not  so  sudden,  and  the  inflam- 
matory symptoms  subside,  the  unfortunate  one  has  a  lingering 
death  of  starvation  from  stricture  of  the  gullet  or  of  the  pylorus, 
and  an  incurable  dyspepsia  due  to  destruction  of  the  coats  of  the 
stomach. 

Fatal  Dose. — The  smallest  fatal  dose  reported  as  given  to  an 
adult  is  60  gr.  (3.8  gm.).  Death  ensued  in  a  child  of  one  year 
after  20  drops.  It  is  difficult  to  state  the  minimum  limit  of  fatal- 
ity, owing  to  the  fact  that  much  depends  on  the  part  touched  by 
the  acid  and  much  on  the  amount  of  food  present  in  the  stomach. 
Even  the  smallest  amount  would  be  permanently  injurious  if  it 
reached  the  gullet,  causing  narrowing  of  the  food  channel.  Few, 


SULPHURIC    ACID  165 

if  any,  infants  survive  this  poison,  and  of  the  adult  cases,  the 
mortality  is  two-thirds. 

Fatal  Period. — In  the  infant  quick  inspiratory  effort  sometimes 
carries  the  poison  into  the  larynx,  and  immediate  death  may  ensue 
from  spasmodic  closure  of  the  glottis.  The  shortest  period 
recorded  for  the  adult  is  one  hour.  Most  cases  die  within  twenty- 
four  or  thirty-six  hours;  some  die  from  sequels  after  weeks,  months, 
or  years. 

Treatment. — Three  objects  are  to  be  kept  in  view:  first,  prompt 
neutralization  of  the  acid;  second,  weakening  by  dilution;  third, 
relief  of  the  asphyxia,  which  sometimes  threatens  life  immediately. 
For  neutralization,  magnesia  and  chalk  are  the  best,  but  in  an 
emergency  soap-suds,  whiting,  or  wall-plaster  (an  impure  cal- 
cium carbonate)  will  serve  the  purpose.  Weak  alkaline  solu- 
tions of  sodium  or  potassium  carbonate  may  be  used  with  caution, 
as  great  distress,  if  not  injury  to  the  weakened  walls,  is  possible 
from  the  stomach  distention  due  to  the  liberation  of  large  quan- 
tities of  carbon  dioxid  gas.  All  the  antidotes  must  be  given  sus- 
pended or  dissolved  in  large  quantities  of  water  or  milk.  In 
the  absence  of  a  neutralizing  antidote  water  alone  must  be  used 
immediately  and  in  large  drafts,  followed  by  raw  eggs.  Should 
symptoms  of  asphyxia  appear  as  a  result  of  laryngeal  implication, 
then  tracheotomy  or  intubation  must  be  resorted  to  at  once. 
Morphin  may  be  given  hypodermically  to  relieve  pain,  and  nutri- 
tive enemata  to  support  life.  The  sequels — perforation,  collapse, 
contraction  of  the  gullet,  gastritis,  and  impaired  digestion — must 
be  treated  by  appropriate  measures  as  the  occasion  requires. 

Postmortem  Appearances. — The  primary  pathologic  changes 
found  when  death  occurs  within  a  few  days  are  those  of  acute  dis- 
organization of  the  structures  of  the  mouth,  gullet,  stomach, 
and  neighboring  parts.  The  lips  and  tongue  are  softened  and 
eroded;  the  throat  and  gullet,  whitish  or  gray  in  color,  the  first 
effect  of  the  acid  on  mucous  surfaces  being  to  coat  them  with 
a  white  paint  of  altered  secretion  and  membrane;  the  stomach  is 
brown-red,  due  to  imbibition  of  altered  hematin,  or  black  from 
charring,  its  mucous  lining  loose  in  shreds  or  patches,  the  folds 
large  and  deep  from  swelling,  sometimes  softened  so  as  to  tear 
under  gentle  manipulation;  the  peritoneum  may  be  blackened 
from  perforation;  the  duodenum  red  and  thickened. 

The  secondary  pathologic  changes,  seen  when  death  follows 
after  several  weeks  of  chronic  illness  from  some  of  the  sequels, 
are  ulceration  of  the  gullet  and  contraction  of  its  caliber  from 
scars;  the  stomach  is  stripped  of  mucous  membrane,  partly  or 
wholly  red,  its  capacity  much  reduced  by  contraction,  and  its 
walls  thickened  and  adherent  to  neighboring  parts. 


l66  NON-METALS 

Tests. — Acid  Test. — The  free  acid,  in  common  with  other  acids, 
reddens  litmus,  turns  cochineal  yellow,  and  decolorizes  red  phenol- 
phthalein. 

Barium  Chlorid  Test. — It  is  customary  to  test  for  sulphuric 
acid  and  the  soluble  sulphates  by  first  acidulating  with  hydro- 
chloric acid  to  prevent  a  precipitate  being  produced  by  the  salts 
of  certain  other  acids,  such  as  carbonic,  phosphoric,  and  oxalic, 
and  then  adding  a  solution  of  barium  chlorid,  which  throws  down 
the  white  barium  sulphate.  Precipitation  is  hastened  and  per- 
fected by  boiling.  This  reaction  occurs  in  the  sense  of  the  fol- 
lowing equation: 

H-,H',(S04)"     +     Ba",Cl',Cl',     =      2H',C1'     +     BaSO4. 

Ions.  Ions.  Ions.  Molecules. 

As  fast  as  the  barium  ions  are  neutralized  by  the  sulphanion, 
the  molecules  of  insoluble  barium  sulphate  are  formed  and,  not 
dissociating,  are  thrown  down.  This  is  in  accordance  with  the 
principle:  //  we  mix  solutions  of  acids,  bases,  and  salts,  any  of 
whose  ions  are  capable  of  uniting  to  form  an  insoluble  compound, 
such  compound  is  formed  and  precipitated. 

Charring  Test. — When  sulphuric  acid  is  applied  undiluted  to 
white  paper  it  darkens,  and  if  gently  heated  chars  the  paper;  even 
if  largely  diluted,  by  heating  the  paper  so  as  not  to  scorch  it,  the 
water  evaporates  and  the  acid  will  reach  the  charring-point.  In 
some  degree  this  property  is  shared  by  hydrochloric  acid. 

Veratrin  Test. — A  drop  of  the  free  acid  will  turn  the  alkaloid 
veratrin  yellow,  and  finally  an  unchanging  crimson.  When  the 
free  acid  is  very  dilute,  a  fragment  of  veratrin  is  dissolved  in  it  by 
the  aid  of  heat,  and  the  colorless  solution,  when  evaporated  to 
dryness  in  a  water-bath,  leaves  a  residue  having  a  crimson  edge, 
which  persists  after  many  hours. 

Detection. — When  the  acid  gets  upon  the  clothing  by  acci- 
dental dropping,  by  expectoration,  or  by  vomiting,  detection  is 
comparatively  easy.  The  strong  acid  will  leave  upon  black  cloth 
a  damp  spot  which  is  at  first  red  and  afterward  dirty  brown  and 
rotten.  If  the  cloth  be  colored  with  indigo-blue,  there  will  be  no 
red  stain;  if  with  logwood  and  madder,  the  stain  will  be  yellow. 
The  stain  left  by  the  dilute  acid  is  also  red,  but  the  spot  dries  out 
and  is  not  corroded.  White  linen  or  cotton  will  be  blackened 
and  eroded. 

After  many  months  or  even  years  the  acid  may  be  detected  in 
the  spot  by  cutting  out  the  piece,  boiling  it  in  i  or  2  c.cm.  (20-40 
drops)  of  distilled  water,  filtering,  and  testing  with  barium  chlorid. 
A  control  experiment  should  be  conducted  simultaneously  with 
a  piece  of  the  unstained  cloth.  Woolen  textures  often  naturally 


SULPHURIC    ACID  167 

contain  sulphates,  but  if  free  sulphuric  acid  be  present,  the  stain 
will  turn  blue  litmus-paper  red,  will  taste  sour,  and  respond  to  the 
veratrin  test.  When  some  of  the  acid  gets  upon  the  lips,  face,  or 
hands,  and  is  not  instantly  wiped  or  washed  away,  the  burned  spot 
does  not  blister,  but  turns  brown,  whereas  with  nitric  acid  it 
would  stain  yellow,  and  with  muriatic  acid  there  would  be  no 
stain  whatever.  The  corroded  skin  soon  sloughs,  and  the  wound 
fills  up  by  granulation,  leaving  a  permanent  scar. 

While  it  is  true  that  the  free  acid  is  very  rarely  found  in  the 
stomach  after  death  and  "the  chemical  detection  of  a  poisoning 
by  nitric  or  sulphuric  acid  is,  as  a  rule,  impossible,"  yet  in  the 
majority  of  cases  detection  is  rendered  sure  by  a  study  of  the 
surroundings,  the  characteristic  pathologic  effects,  and  the  stains. 
Sometimes  it  happens  that  these  are  not  conclusive,  and  appeal 
must  be  taken  to  a  quantitative  analysis.  The  gastric  secretions 
and  the  food  always  contain  some  sulphates;  others,  such  as 
magnesium  sulphate,  may  have  been  given  as  a  medicine.  It  is, 
therefore,  necessary  to  estimate  the  total  quantity  of  sulphates 
present,  and  judge  if  the  amount  be  greater  than  normal,  and  if 
it  can  be  accounted  for  in  any  other  way  than  by  the  administra- 
tion of  the  acid  itself.  The  mineral  acids  are  usually  separated 
from  organic  matter  by  digesting  the  mixture  in  distilled  water 
for  several  hours.  An  acid  reaction  with  litmus  would  point  to 
free  acid,  and  the  degree  of  acidity  could  be  determined  by  allowing 
the  suspended  matter  to  subside  and  then  titrating  a  definite  portion 
with  decinormal  sodium  hydroxid,  using  phenolphthalein  as  an 
indicator.  Some  degree  of  acidity  must  be  expected  of  the  gastric 
contents  from  the  presence  of  natural  acids — hydrochloric,  lactic, 
acetic,  or  butyric.  The  normal  amount  is  so  slight — not  more 
than  0.3  per  cent. — that  any  considerable  showing  of  acid  would 
be  very  significant. 

To  get  the  free  sulphuric  acid  apart  from  free  hydrochloric  or 
butyric  acids  and  separated  from  the  sulphates  and  phosphates 
the  watery  extract  above  referred  to  should  be  evaporated  to 
dryness  and  treated  with  a  mixture  of  equal  parts  of  alcohol  and 
ether.  This  mixture  will  separate  the  free  sulphuric  and  phos- 
phoric acids  and  then  by  precipitation  with  acidified  barium 
chlorid,  boiling  and  weighing  the  dried  precipitate  of  barium  sul- 
phate, the  amount  of  free  sulphuric  acid  can  be  ascertained.  The 
total  quantity  of  the  free  acid  and  that  combined  as  sulphates  may 
be  calculated  by  precipitation  with  barium  chlorid  from  a  definite 
fraction  of  the  liquid  containing  a  small  amount  of  hydrochloric 
acid  and  heated  to  boiling.  The  liquid  should  be  decanted,  the 
precipitate  washed,  collected  on  a  filter,  dried,  and  weighed.  One 
hundred  parts  of  the  barium  sulphate  precipitated  represent  42 


l68  NON-METALS 

parts  of  absolute  sulphuric  acid  (H2SO4),  or  34.3  parts  of  sulphuric 
anhydrid  (SO3).  By  comparing  the  result  with  the  small  amount  of 
sulphuric  acid  ordinarily  present  in  a  mixed  meal  (not  more  than 
0.6  gm.  or  10  gr.),  the  fact  of.  excess  can  be  made  out. 

The  tissues  rarely  show  free  sulphuric  acid,  owing  to  its  reaction 
with  the  phosphates.  It  forms  sulphates  with  the  bases  and 
liberates  the  phosphoric  acid.  If  the  extract  made  with  alcohol 
and  ether,  as  stated  above,  when  treated  with  ammonium  molyb- 
date,  should  yield  a  yellow  precipitate,  this  would  be  an  indica- 
tion that  free  sulphuric  acid  had  been  present,  unless  it  could  be 
shown  that  free  phosphoric  acid  had  been  given. 

As  the  proportion  of  sulphates  normally  present  in  the  urine 
varies  with  the  individual,  and  in  the  same  person  changes  from 
day  to  day,  no  forensic  importance  is  to  be  attached  to  the  anal- 
ysis of  the  urine. 

Oxyacids  of  Sulphur. — The  compounds  of  sulphur  with 
oxygen  and  hydrogen  are  as  follows: 

Thiosulphuric  acid,  H2S2O3,  Persulphuric  acid,  H2S2O8, 

Hydrosulphurous  acid,  H2S2O4,  Dithionic  acid,  H2S2O6 

Sulphurous  acid,  H2SO3,  Trithionic  acid,  H2S3O6, 

Sulphuric  acid,  H2SO4,  Tetrathionic  acid,  H2S4O6, 

Pyrosulphuric  acid,  H2S2O7,  Pentathionic  acid,  H2S5O6. 

The  acids  sulphurous,  sulphuric,  pyrosulphuric  (Nordhausen), 
and  hyposulphurous  are  of  importance,  but  little  is  as  yet  known 
concerning  the  others. 

Thiosulphuric  Acid  (H2S2O3)  (Hyposulphurous}.— The  anion 
of  this  acid  is  (S2O3)",  which  differs  from  the  sulphuric  ion  (SO4)" 
by  having  one  oxygen  replaced  by  one  sulphur  atom.  This  gives 
the  name  thiosulphuric  from  thion,  the  Greek  for  sulphur.  It 
is  commonly  known  only  in  a  combination  such  as  sodium  hypo- 
sulphite (thiosulphate),  Na2S2O3  +  5H2O,  or  potassium  hyposul- 
phite (thiosulphate),  K2S2O3  +  5H2O.  These  salts  have  the  power 
of  dissolving  the  silver  salts  which  have  escaped  the  action  of  light, 
and  are  largely  used,  under  the  name  hypo,  for  fixing  the  image 
in  photography.  Sodium  hyposulphite  is  prepared  by  passing 
sulphur  dioxid  into  a  mixture  of  sodium  sulphid  and  caustic  soda. 
Thus: 

2Na2S     +      2NaHO      +     4SO2     =     H2O     +     3.Na2S2O3. 

SELENIUM  TELLURIUM 

Symbol,  Se.     Atomic  weight,  79.2.  Symbol,  Te.     Atomic  weight,  127. 

Selenium  is  found  associated  with  sulphur  and,  like  it,  has 
different  allotropic  forms.  The  amorphous  variety  is  a  black  or 
dark-red  solid  which,  kept  at  a  temperature  of  150°  C.,  changes 


COMPOUNDS    OF    NITROGEN    AND    OXYGEN  169 

to  the  crystalline  variety,  gray,  and  with  a  metallic  luster.  Its 
electric  conductivity  varies  directly  as  the  light  it  receives.  Tellu- 
rium forms  grayish-white  crystals  with  a  metallic  luster  occurring 
free  in  nature  or  as  tellurid  of  gold  and  other  metals.  Both  of 
these  non-metals  are  very  rare,  being  found  in  small  quantities. 
Closely  allied  to  sulphur  they  form  anhydrids  like  SO2  and  SO3, 
which,  with  water,  form  -ous  and  -ic  acids,  H2SeO3  and  H2SeO4, 
and  H2TeO3  and  H2TeO4;  analogous  to  H2SO3  and  H2SO4.  With 
hydrogen  they  form  gases,  H2Se  and  H2Te,  which  resemble  H2S 
in  their  mode  of  formation,  their  odor,  and  their  reaction  with 
metallic  solutions,  but  which  are  less  stable,  with  odors  more 
disgusting  than  hydrogen  sulphid.  All  of  them  on  combustion 
yield  dioxids. 

Sulphur  Group. — A  trinity  corresponding  to  the  halogens  is 
formed  by  sulphur,  selenium,  and  tellurium.  They  are  divalent 
and  sometimes  tetravalent,  hexavalent,  or  octavalent.  Their 
atomic  weights  are  S.,  32;  Se.,  79.2;  Te.,  127.  The  mean  is  79.5, 
which  is  nearly  the  atomic  weight  of  Se.  Their  properties  are 
similar,  but  vary  in  the  order  of  their  atomic  weight. 

COMPOUNDS  OF  NITROGEN  AND  OXYGEN 

Nitric  Acid  (HNO3)  (Aqua  Fortis). — Occurrence. — Nitric 
acid  is  not  free  in  nature.  As  the  result  of  the  oxidation  of  nitrog- 
enous animal  matter  potassium  and  sodium  nitrate  are  widely 
disseminated,  especially  in  guano  deposits.  The  nitrates  are  also 
to  be  found  in  traces  in  rain-water  and  in  the  surface  wells  of  towns. 

Preparation. — Either  potassium  or  sodium  nitrate  will  yield 
nitric  acid  when  distilled  with  sulphuric  acid.  Though  nitric  acid 
is  the  stronger  acid,  yet,  owing  to  its  volatility,  it  gives  place  to  sul- 
phuric acid,  which  is  non-volatile.  This  is  according  to  a  general 
law:  that,  given  the  materials  to  form  a  volatile  compound,  it  is 
always  jormed  and  passes  off  in  vapor. 

NaN03      +      H2S04  NaHSO4      +      HNO3. 

Sodium  nitrate.  Monosodium  sulphate. 

Physical  Properties. — Pure  nitric  acid  is  a  colorless  liquid, 
boiling  at  86°  C.  (186.8°  F.)  and  solidifying  at  -47°  C.  (-52.6° 
F.).  The  commercial  article  is  yellow  and  of  two  different 
strengths:  single  aqua  fortis,  specific  gravity  1.25,  containing  39 
per  cent,  of  HNO3,  and  double  aqua  fortis,  specific  gravity  1.4, 
with  64  per  cent,  of  HNO3.  Red  fuming  nitric  acid  has  a  specific 
gravity  1.6  and  is  obtained  by  distilling  at  a  high  temperature  or 
by  adding  reducing  organic  matter  during  distillation. 

Chemical  Properties. — Nitric  acid  takes  rank  with  the  strong- 
est acids  because  it  dissociates  hydrion  to  a  great  degree.  For 


I  yo  NON-METALS 

the  same  reason  its  conductivity  as  an  electrolyte  is  high.  It  attacks 
and  dissolves  all  the  metals  except  gold  and  the  platinum  family. 
Its  neutral  salts,  the  nitrates,  are  all  soluble  in  water.  The  com- 
pound formed  with  albumin  is  insoluble.  Nitric  acid  does  not 
keep  pure  long,  the  sunlight  alone  having  power  to  decompose  it 
into  oxygen,  water,  and  lower  nitrogen  oxids  of  a  yellow  color 
which  dissolve  in  the  water. 

2HNO3  N2O4         +         H2O         +         O. 

Nitrogen  tetroxid. 

The  strong  tendency  of  nitric  acid  to  form  ions  makes  easy 
this  production  of  water.  The  hydrion  H%  stimulated  by  sun- 
light, breaks  up  the  anion  (NO3)'  because  it  appropriates  the 
oxygen  ions  forming  undissociated  water  molecules.  The  velocity 
with  which  the  oxidizing  effect  is  produced  is  accelerated  by  the 
presence  of  N2O4  acting  as  a  catalyzer.  Hence  for  high  oxidation 
effects  the  red  fuming  acid  is  preferred. 

Most  of  the  value  of  nitric  acid,  chemically,  is  due  to  this  insta- 
bility, which  it  shares  with  ozone  and  hydrogen  dioxid.  In  the 
presence  of  substances  that  can  be  oxidized  this  power  is  exerted 
to  a  marked  extent,  red  fumes  of  lower  oxids  arising.  In  its 
reaction  with  metals  the  hydrogen  is  not  always  liberated,  but  is 
taken  up  by  the  oxygen  to  form  water,  thus  causing  the  forma- 
tion of  the  reddish  nitrous  fumes.  It  is  a  monobasic  acid  disso- 
ciating as  H',(NO3)'  and  yielding  but  one  class  of  salts,  such 
as  Na',  (NO3)'. 

Technical  Uses. — Metal  workers  use  this  acid  for  etching  and 
for  cleansing  preparatory  to  gilding  and  lacquering.  Of  late 
years  it  has  had  a  great  extension  of  employment  in  the  making 
of  various  organic  nitrocompounds,  such  as  gun-cotton,  celluloid, 
nitroglycerin,  dynamite,  and  picric  acid.  Dyers,  hatters,  and 
chemists  have  need  for  it. 

Medical  Uses. — It  is  used  in  medicine  as  a  valued  caustic  only 
under  the  official  name  acidum  nitricum,  of  specific  gravity  1.40, 
containing  68  per  cent.  HNO3.  On  prolonged  exposure  to  light 
and  air  the  lower  oxids  of  nitrogen  are  developed  and  impart 
a  yellow  color.  It  is  then  called  nitrosonitric  or  fuming  acid, 
useful  as  a  reagent  for  biliary  coloring  matter  in  Gmelin's  test. 
As  an  escharotic  it  corrodes  organic  matter  by  oxidation,  not  by 
carbonizing,  as  sulphuric  acid  does.  Animal  matter  is4  turned 
a  deep  yellow,  the  color  of  picric  acid.  Albumin  is  coagulated  by 
it,  and  if  the  acid  be  strong  the  white  coagulum  turns  the  char- 
acteristic yellow.  It  gives  promptly  the  acid  reaction  with  litmus 
and  other  color  indicators.  If  concentrated  it  turns  litmus  yellow. 


COMPOUNDS    OF    NITROGEN    AND    OXYGEN  17 1 

Acidum  nitricum  dilutum  (U.  S.),  specific  gravity  1.054,  con- 
taining 10  per  cent.  HNO3,  is  the  only  form  suited  for  internal 
administration.  The  dose  is  5-15  tit  (0.33-1  c.c.),  largely  diluted. 

Incompatibles. — Alkalies  and  alkaline  earths  and  their  car- 
bonates, calomel,  and  other  mercurous  salts. 

Toxicology. — Although  widely  used  in  the  arts,  this  acid  fig- 
ures as  a  poison  much  less  frequently  than  does  sulphuric  acid. 
History  shows  that  most  of  the  cases  are  suicidal,  and  when  the 
intent  is  homicidal,  the  victim  is  either  a  child  or  an  adult  ren- 
dered unconscious  by  sleep  or  drunkenness.  It  would  not  be 
possible  to  give  it  in  food  or  medicine  without  detection. 

Symptoms. — There  is  no  important  difference  from  the  symp- 
toms produced  by  sulphuric  acid  and  already  described  (p.  164), 
with  the  exception  of  the  color  of  the  mouth  and  lips,  which,  with 
nitric  acid,  is  intensely  yellow,  though  at  first  the  parts  are  blanched 
and  white.  There  are  intense  pain,  vomiting,  thirst,  and  great 
depression.  Eructations  of  gas  are  frequent  and  distressing,  due 
to  its  direct  development  by  the  action  of  the  acid  on  organic  sub- 
stances. 

Fatal  Dose, — Three  fluidrams  by  the  mouth  in  adults  have 
destroyed  life,  but  a  much  smaller  quantity  would  suffice  to  cause 
fatal  suffocation  from  spasmodic  closure  if  it  were  to  enter  the 
larynx,  as  it  is  likely  to  do  in  children. 

Fatal  Period. — The  average  duration  of  life  is  about  twenty- 
four  hours;  the  shortest  time  reported  in  the  case  of  an  adult 
was  an  hour  and  three-quarters,  while  a  case  is  recorded  of  an 
infant  who  died  in  a  few  minutes.  In  some  cases  death  has  been 
delayed  for  weeks,  months,  or  years,  the  remote  effects  of  the 
poison  then  proving  fatal. 

Treatment. — The  extraordinary  energy  and  rapidity  of  action 
of  nitric  acid  make  it  difficult  to  administer  antidotes  with  sufficient 
promptness  to  be  of  much  help.  It  is  always  advisable  to  use 
chalk,  whiting,  magnesia  in  milk,  soapsuds,  and  eggs  as  anti- 
dotes, with  the  hope  of  neutralizing  some  free  acid.  The  method 
is  the  same  as  for  sulphuric  acid  and  for  the  corrosive  acids  gen- 
erally. In  all  there  is  instant  local  death  of  parts  struck  by  the 
poison,  rapidly  followed  by  inflammation  of  surrounding  viscera. 
Our  antidotes  cannot  restore  the  tissues  to  health,  nor  can  they 
diffuse  into  distant  parts  fast  enough  to  be  of  much  avail.  The 
symptoms  must  be  treated  on  general  principles  as  they  appear. 

Postmortem  Appearances. — All  the  parts  to  which  the  acid  is 
applied  present  the  various  marks  of  erosion — in  places  harden- 
ing and  thickening,  in  others  ulceration  and  sloughing,  general 
pulpiness,  shreddy  mucous  surfaces  denuded  of  membrane,  and 
perforations  of  the  gullet,  the  stomach,  or  the  intestine.  The 


172  NON-METALS 

most  characteristic  pathologic  change  is  the  permanent  citron- 
yellow  or  orange-brown  color  of  the  tissues  acted  on. 

Tests. — Even  when  very  largely  diluted — that  is,  0.2  per  cent. — 
the  acid  reddens  litmus  (see  Tests  for  Free  Mineral  Acids,  p.  138). 

Copper  Test. — Poured  upon  slips  of  copper  and  gently  heated, 
effervescence  occurs  and  red-brown  vapors  arise  that  redden  moist 
litmus-paper.  If  the  amount  of  nitric  acid  be  small,  the  color  of 
the  fumes  may  not  be  noticed,  and  a  more  delicate  test  is  required. 
By  holding  in  the  vapors  a  piece  of  paper  moistened  with  potas- 
sium iodid  and  starch  paste  a  blue  color  develops. 

Brucin  Test. — Upon  a  crystal  of  brucin  a  drop  of  nitric  acid 
strikes  a  blood-red  color;  upon  morphin  an  orange  hue,  with 
orange-colored  fumes. 

Ferrous  Sulphate  Test. — Upon  a  white  porcelain  surface  put 
a  few  drops  of  the  suspected  liquid,  a  drop  of  sulphuric  acid,  and 
a  crystal  of  ferrous  sulphate;  the  crystal  turns  dark-green,  and 
finally  brown.  Even  the  combined  acid  in  nitrates  yields  the 
same  proof  with  any  of  the  above  tests,  provided  pure  sulphuric 
acid  is  first  used  to  free  the  nitric  acid.  If  eggs  have  been  given 
as  an  antidote,  the  nitric  acid  must  be  taken  from  the  albumin  by 
means  of  a  solution  of  potassium  carbonate;  the  resulting  soluble 
nitrate  can  then  be  treated  by  equal  parts  of  sulphuric  acid  and 
water  before  applying  the  above  tests. 

Detection. — On  inspection  the  stains  left  on  the  clothing  will 
be  found  dry  and  partaking  of  the  same  citron-yellow  change 
found  on  the  skin  or  other  animal  tissue  touched  by  this  acid. 
The  yellow  stain  produced  by  tincture  of  iodin  is  discharged  by 
potassium  hydroxid  or  by  ammonia-water,  but  the  nitric-acid 
stain  is  indelible;  ammonia  and  the  alkalies  only  intensify  it  to 
an  orange  hue.  If  the  piece  of  stained  cloth  be  boiled  in  some 
distilled  water,  litmus-paper  will  reveal  the  acid  reaction.  When 
the  acid  liquid  is  neutralized  with  potassium  carbonate,  filtered 
and  evaporated  to  dryness,  crystals  of  potassium  nitrate  form. 
When  these  crystals  are  dissolved  in  water  and  a  drop  of  pure 
sulphuric  acid  is  added,  the  nitric  acid  is  set  free  and  strikes  a 
blood-red  color  with  brucin,  yields  ruddy  fumes  with  copper 
turnings,  or  responds  to  the  ferrous-sulphate  test  for  nitric  acid. 

If  the  vomited  matters  be  decidedly  acid,  the  acidity  should  be 
measured  by  titration  with  decinormal  solution  of  sodium  hy- 
droxid. The  resulting  sodium  nitrate  can  then  be  tested  by 
treating  with  sulphuric  acid  and  applying  any  of  the  tests  above 
mentioned. 

As  nitrates  are  not  constituents  of  ordinary  food  or  of  the  ani- 
mal tissues,  it  is  proof  enough  if  these  be  found  in  any  amount 
above  a  trace.  It  is  not  necessary  to  make  a  quantitative 


COMPOUNDS    OF    NITROGEN    AND    OXYGEN  173 

analysis.  The  vomited  matters  or  the  tissues  should  be  extracted 
with  boiling  distilled  water  and  potassium  carbonate  and  then 
filtered.  Crystals  of  potassium  nitrate  are  obtained  on  evapora- 
tion which  respond  to  all  the  tests  given  above  for  nitrates. 

Fumes  of  Nitric  Acid. — The  emanations  of  nitric  acid  are  a 
mixture  of  nitric  acid  vapor  with  various  lower  oxids,  all  of  them 
offensive  and  irritating  to  the  air-passages.  In  the  industries 
mentioned  above  as  making  use  of  this  acid  these  vapors  may  do 
great  harm  if  the  processes  be  not  carried  on  in  closed  vessels 
and  the  noxious  fumes  passed  into  milk  of  lime.  The  habitual 
breathing  of  air  containing  only  a  small  amount  frequently  leads 
to  severe  chronic  bronchitis  with  general  impairment  of  health. 
In  the  annals  of  toxicology  cases  of  acute  poisoning  are  reported 
from  chemists  suddenly  inhaling  the  fumes  rising  when  a  carboy 
of  the  acid  has  been  accidentally  broken.  The  symptoms  are  like 
those  of  capillary  bronchitis. 

In  fatal  cases  there  is  found  usually  congestion  of  the  larynx, 
trachea,  and  bronchial  tubes,  and  sometimes  edema  of  the  lungs 
or  effusion  of  blood.  Although  the  effects  appear  to  be  mainly 
those  of  direct  irritation,  some  cases  show  inflammatory  changes 
in  the  lining  of  the  right  auricle.  Acute  cases  should  be  treated 
by  fresh  air  and  inhalations  of  ether  to  relieve  the  sense  of  con- 
striction. 

Nitromuriatic  Acid  (Acidum  Nitrohydrochloricum,  U.  S.). — 
By  mixing  i  part  of  nitric  and  3  parts  of  hydrochloric  acid  the 
commercial  aqua  regia  is  prepared.  This  is  an  unstable  liquid, 
evolving  free  chlorin  and  other  gases,  and  eventually  becoming 
much  weaker  than  when  first  made.  The  nitric  acid  oxidizes  the 
hydrochloric,  taking  its  hydrogen  to  form  water  and  liberating 
chlorin  and  nitric  oxid: 

HC1      +     HN03    =      Cl       +       N02       +     H20. 

The  nascent  chlorin  will  act  on  gold  and  platinum,  forming 
soluble  chlorids.  It  dissolves  all  the  metals,  including  gold  and 
platinum,  and  oxidizes  iodin,  phosphorus,  and  sulphur.  It  coagu- 
lates albumin,  turns  it  yellow,  and  finally  dissolves  it,  as  it  does 
all  vegetable  and  animal  substances,  with  the  production  of 
ruddy  fumes. 

Acidum  Nitrohydrochloricum  Dilutum  (U.  S.). — Dose,  5-8  HI 
(0.30-0.50  c.c.).  While  the  dilute  acid  is  given  internally  as  a  medi- 
cine, the  concentrated  acid  is  an  exceedingly  corrosive  poison,  the 
symptoms  and  postmortem  appearances  of  which  differ  from  those 
of  nitric  acid  in  degree  only.  The  antidotes  are  the  same  as  for 
the  other  mineral  acids. 


174  NON-METALS 

NITROGEN    OXIDS 

In  nature  certain  bacteria  growing  in  nodules  on  the  roots  of 
leguminous  plants  have  the  power  of  uniting  the  nitrogen  and 
oxygen  of  the  air,  enriching  the  soil  with  nitrates.  By  passing 
streams  of  electric  sparks  through  the  air  an  acrid  smell  is  per- 
ceived and  red  vapors  arise.  These  are  nitrogen  trioxid  and 
tetroxid,  and,  when  washed  down  with  alkaline  fluids,  nitrites  and 
nitrates  are  formed.  In  another  place,  as  illustrating  the  law  of 
multiple  proportions,  the  following  five  compounds  have  been 
mentioned: 

Nitrogen  pentoxid,  or  nitric  anhydrid N2O5. 

Nitrogen  tetroxid,  or  dioxid NO2  or  N2O4. 

Nitrogen  trioxid,  or  nitrous  anhydrid N2O3. 

Nitric  oxid NO. 

Nitrogen  monoxid,  nitrous  oxid,  or  laughing  gas  ....  N2O. 

Nitrogen  pentoxid,  N2O5  (anhydrous  nitric  acid),  can  be 
prepared  by  removing  water  from  2  molecules  of  nitric  acid, 
H2N2O6,  which  then  becomes  N2O5.  Nothing  will  serve  but  the 
most  powerful  dehydrating  substance,  phosphorus  pentoxid,  P2O5. 
The  mixture  distilled  yields  the  nitric  anhydrid  as  a  white  crystal- 
line substance.  This  easily  decomposes  by  reversing  the  process 
by  which  it  was  made,  taking  up  the  elements  of  water. 

N2O5    +    H2O      =      H2N2O6  or  2HNO3. 

Nitric  Oxid  (NO).— By  analytic  methods  it  has  been  shown  that 
a  number  of  lower  oxids,  reduction  products,  are  formed  by  the  action 
of  HNO3  on  copper  or  other  metals.  They  vary  according  to  the 
concentration  of  the  acid,  the  nature  of  the  metal,  and  the  tempera- 
ture. The  one  yielded  most  easily  when  copper  clippings  are  used  as 
the  metal  is  the  gas  NO.  The  reaction  is  as  follows: 

3Cu     +     8HN03     =     3Cu(N03)2     +     2NO     +     4H2O. 

Copper  nitrate.  Nitric  oxid. 

The  first  brown  vapors  are  made  colorless  in  passing  through 
the  pneumatic  trough.  This  colorless  gas,  NO,  is  feebly  soluble. 
It  neither  burns  nor  supports  combustion.  If  collected  in  a  bell 
jar  and  oxygen  omitted,  there  is  instant  union,  with  the  formation  of 
reddish-brown  nitrogen  dioxid:  NO  +  O=NO2.  This  red  gas  is  dis- 
solved by  the  water  which  rises  in  the  jar  as  the  volume  of  the 
residual  gas  diminishes.  Nitrogen  dioxid  is  taken  up  by  solution 
of  ferrous  sulphate,  which  turns  dark  brown  (see  Tests  for  Nitric 
Acid,  p.  172). 


COMPOUNDS    OF    NITROGEN    AND    OXYGEN 


Nitrogen  Tetroxid  (N2O4)  (Nitrogen  Peroxid,  Hyponitric 
Acid). — The  brown-red  fumes  formed  by  the  union  of  NO  with 
oxygen  in  the  air  can  be  condensed  to  a  yellow  liquid  which 
loses  color  with  an  accompanying  decline  of  temperature.  It 
solidifies  at  — 12°  C.  (—10.4°  F.)  into  colorless  crystals.  A  study 
of  the  vapor  density  shows  that  the  dark-red  gas  at  100°  C. 
(212°  F.)  has  the  formula  NO2,  but  the  almost  colorless  gas 


FIG.  54. — Apparatus  for  generating  nitrogen  dioxid. 

below  o°  C.  (32°  F.)  has  the  formula  N2O4  or  2(NO2).  At  in- 
termediate temperatures  the  gas  is  a  mixture  of  the  two  forms. 
As  stated  above,  it  is  the  final  product  of  electric  discharges  in 
the  air,  and  dissolved  in  water  it  decomposes  into  nitric  and 
nitrous  acids. 


N204 


H90 


HNCX 


HN02. 


Nitric  acid.  Nitrous  acid. 

Toxicology. — In  the  manufacture  of  gun-cotton,  oil  of  vitriol, 
oxalic  acid,  nitrobenzol,  picric  acid,  and  in  metal  working  and 
gilding,  the  deoxidized  nitric  acid  is  the  source  of  offensive,  irri- 
tating, and,  when  very  strong,  deadly  vapors,  of  which  the  chief 
constituent  is  nitrogen  tetroxid.  Workmen  breathing  it  habitu- 
ally suffer  from  chronic  bronchitis  with  cough,  suffocative  attacks, 
dysuria,  and  delirium.  These  symptoms  may  culminate  in  death. 

Nitrous  Acid  (HNO2).— On  reducing  potassium  nitrate  with 
lead  a  salt  is  formed  having  less  oxygen:  potassium  nitrite. 


KNO, 


Pb 


KNO, 


PbO. 


Nitrate.  Nitrite. 

The  nitrite  being  soluble  can  be  removed  by  water  from  the 
insoluble  lead  oxid.  Again,  by  carefully  heating  KNO3  it  loses 
oxygen,  yielding  the  nitrite: 


2KNO3 


O, 


2KNO,. 


176  NON-METALS 

The  acid,  as  such,  cannot  be  liberated  from  this  salt  by  the 
action  of  sulphuric  acid;  it  is  too  unstable  at  ordinary  temperatures, 
but  brownish  vapors  arise  of  nitrogen  trioxid,  N2O3,  sometimes 
called  nitrous  anhydrid,  which  decomposes  into  NO2  +  NO.  It 
condenses  to  a  dark  indigo-blue  liquid  which  boils  at  o°  C.  (32°  F.) 
and  solidifies  at  —82°  C.  (—115.6°  F.).  This  brown  gas  passed 
into  water  forms  a  blue  solution  containing  some  nitrous  acid, 
but  soon  decomposes  into  nitrogen  dioxid,  nitric  acid,  and  water. 

3HN02       =       2NO        +      HN03        +      H20. 

Nitrous  acid.  Nitric  acid. 

Tests  for  Nitrites.— Salts  having  the  ion  (NO2)'  give  the  same 
brown  reaction  with  ferrous  sulphate  as  that  referred  to  among 
the  tests  for  nitric  acid;  but  when  treated  with  sulphuric  acid  the 
nitrites  are  peculiar  in  yielding  the  brown  vapors  of  N2O3.  Nitrites 
deoxidize  and  decolorize  instantly  the  purple  solution  of  potas- 
sium permanganate. 

Nitrous  oxid  (N2O)  (Nitrogen  monoxid,  "Laughing  Gas").— 
Preparation. — By  gradually  heating  ammonium  nitrate  to  250° 
C.  (482°  F.)  in  a  retort  the  crystals  melt  and  easily  decompose, 
water  being  formed  and  a  permanent  gas  generated,  capable  of 
being  collected  over  hot  water  or  mercury. 

NH4NO3  N2O         +         2H2O. 

Ammonium  nitrate.  Nitrous  oxid. 

To  purify  the  product  for  inhalation  the  gas  should  be  passed 
through  warm  solutions  of  sodium  hydroxid  and  ferrous  sul- 
phate. 

Properties. — Nitrous  oxid  is  a  colorless  gas  with  a  sweetish 
odor  and  taste;  it  is  soluble  in  an  equal  volume  of  water  and  readily 
liquefied  by  pressure.  The  liquid  is  a  useful  refrigerating  agent. 
Nitrous  oxid  does  not  burn,  but  yields  oxygen  to  burning  sub- 
stances, supporting  the  combustion  of  carbon  and  phosphorus 
almost  as  well  as  oxygen.  It  does  not  part  with  its  oxygen  to 
burning  sulphur  when  the  flame  is  small,  but  with  a  large  flame 
forms  SO2  just  as  would  free  oxygen.  It  does  not  break  up  and 
give  oxygen  to  the  body.  Hemoglobin  cannot  use  it. 

Physiologic  Effect. — Nitrous  oxid  gets  the  name  laughing  gas 
from  the  gay  intoxication  first  caused  by  inhaling  it  mixed  with 
air.  When  pushed  beyond  this  hysteric  stage  or  when  inhaled 
pure  the  effects  are  those  of  a  transient  narcotic. 

Toxicology. — As  the  organism  does  not  have  the  power  to 
utilize  the  oxygen  in  this  gas  when  it  is  inhaled,  along  with  anes- 
thesia, some  asphyxia  is  produced,  which  in  healthy  subjects  can 
be  borne  long  enough  for  short  operations,  such  as  tooth  extrac- 
tion. To  prolong  its  effects  with  safety  oxygen  must  be  mixed 


PHOSPHORUS  177 

with  it.     Very  rarely  its  administration  has  been  fatal;  some  heart 
weakness  is  responsible  for  this  result  in  most  cases. 

HyponitTOUS  Acid  (HNO).  —  This  substance  can  be  obtained 
in  white  crystalline  scales  which  readily  explode,  owing  to  their 
instability.  Dissolved  in  water,  it  soon  evolves  the  gas  nitrogen 
monoxid,  N2O.  Sodium  hyponitrite  is  a  permanent  salt  made  by 
the  reduction  of  sodium  nitrite  with  metallic  sodium  in  amalgam: 

NaNO2        +     2Na    +     H2O     =        NaNO    +     2NaHO. 

Sodium  nitrite.  Sodium  hyponitrite. 

PHOSPHORUS 

Symbol,  P.     Atomic  weight,  31. 

Occurrence.  —  This  element  is  not  found  free  in  nature,  occur- 
ring in  combination  mainly  as  phosphates  in  various  minerals  of 
the  soil  and  in  the  structure'  of  plants  and  animals.  It  was  first 
discovered  as  a  constituent  of  human  urine. 

Preparation.—  Phosphorus  is  made  from  bone-ash,  Ca3  (POJ2, 
by  heating  it  with  carbon  and  sand  in  an  electric  furnace.  This 
reduces  the  bone  phosphate  of  calcium  to  elementary  phosphorus, 
which  is  distilled  and  run  into  molds  under  warm  water  to  make 
stick  phosphorus. 


2Ca3(PO4)2  +    loC    +    6SiO2    =    loCO    +    6CaSiO2    +    P4. 

Calcium  phosphate.  Silicon  dioxid.  Calcium  silicate. 

Properties.  —  The  ordinary  crystalline  or  waxy  form  usually 
occurs  in  translucent  cylinders  which  cut  like  wax,  and  when 
kept  under  water  turn  yellow  and  become  coated  with  a  thin 
white  crust.  As  it  oxidizes  in  the  air  it  should  be  kept  under 
water  that  has  been  well  boiled  to  expel  dissolved  oxygen.  It 
takes  fire  at  50°  C.  (122°  F.),  a  temperature  easily  reached  by 
friction  between  the  fingers,  hence  the  caution  to  handle  it  with 
forceps.  If  it  should  take  fire  in  the  hand,  it  will  burn  severely, 
and  at  the  same  time  more  or  less  of  the  poison  will  be  absorbed. 
The  poison  in  the  burn  should  be  made  inert  by  a  lotion  of  chlo- 
rinated soda  or  a  paste  of  chlorinated  lime. 

It  has  the  odor  and  taste  of  garlic,  is  very  sparingly  soluble 
in  water,  slightly  soluble  in  alcohol  and  glycerin,  but  freely  so  in 
carbon  bisulphid,  almond  oil,  and  ether.  Under  water  at  44.5°  C. 
(m°  F.)  it  melts  to  an  oily  fluid,  which  can  be  run  into  cylindric 
molds.  Exposed  to  the  air,  white  fumes  of  its  lower  oxid,  P2O3, 
are  evolved,  and  in  the  dark  emit  a  feeble  light.  Black  and  white 
phosphorus  are  modifications  of  no  practical  importance. 

Red  phosphorus  is  an  allotropic  form  made  by  heating  the 
waxy  variety  in  a  closed  vessel  without  air  for  thirty-six  hours. 


178  NON-METALS 

It  is  a  red-brown  crystalline  powder,  insoluble  in  the  solvents  for 
waxy  phosphorus,  does  not  oxidize  in  air,  is  not  luminous,  need 
not  be  kept  under  water,  and  requires  a  much  higher  temperature 
to  inflame  it  than  does  the  waxy  form.  It  does  not  take  fire 
unless  heated  to  280°  C.  (536°  F.).  The  pure  red  phosphorus 
is  not  poisonous,  but  the  commercial  article  sometimes  contains  as 
much  as  0.6  per  cent,  of  the  waxy,  poisonous  form. 

The  lucijer  matches  commonly  sold  are  tipped  with  waxy  or 
poisonous  phosphorus  mixed  with  potassium  chlorate,  sand,  and 
glue,  but  the  " safety-match"  is  tipped  with  potassium  chlorate 
and  antimony  sulphid  without  phosphorus.  In  order  to  light  the 
"safety-match"  it  must  be  rubbed  upon  the  side  of  the  containing 
box,  which  is  covered  with  a  thin  coat  of  red  or  non-poisonous 
phosphorus,  mixed  with  sizing. 

There  is  some  resemblance  between  nitrogen  and  phosphorus 
in  their  corresponding  compounds  with  hydrogen,  both  forming 
gaseous  compounds,  NH3  and  PH3;  with  oxygen,  N2O3,  N2O5  and 
P2O3,  P2O5.  Like  nitric  acid,  HNO3,  there  is  a  metaphosphoric 
acid,  HP03. 

The  molecular  weight  of  phosphorus  is  124,  which  is  four 
times  the  atomic  weight,  31;  hence  there  must  be  four  atoms  in 
its  molecule. 

Pharmaceutic  Preparations.— In  Pilulae  phosphori  (U.  S.  P.) 
the  pill  mass  is  made  with  althaea  and  acacia,  and  each  pill  is  coated 
with  balsam  tolu.  The  presence  of  the  free  phosphorus  can  be  shown 
by  cutting  the  pill  open  and  exposing  the  mass  to  gentle  heat  in  the 
dark.  It  should  "  phosphoresce  " — i.  e.,  emit  light.  Sometimes  it  is 
given  in  a  solution  in  almond  oil  of  i  per  cent,  strength.  Spiritus 
phosphori  is  an  official  solution  in  absolute -alcohol  of  about  o.i  per 
cent,  strength.  An  ethereal  solution  is  also  used. 

Toxicology. — As  alkaline  and  earthy  phosphates,  it  is  a 
constituent  of  the  tissues  and  fluids  of  the  human  body;  it  is 
found  largely  in  the  bones  as  calcium  phosphate  and  in  the  nervous 
centers  as  a  compound  with  fat  and  albumin.  Ever  since  it  was 
first  used  to  tip  lucifer  matches  its  poisonous  properties  have  been 
known;  indeed,  on  the  Continent  of  Europe  it  has  been  the  favorite 
rat  poison.  While  the  other  active  poisons  are  guarded  by  law 
from  general  distribution,  this  one  is  easily  obtained  as  the  heads 
of  matches  and  as  "rat-paste,  "  which  contains  from  i  to  4  per  cent. 
of  phosphorus  mixed  with  oil,  flour,  sugar,  and  coloring-matter.1 
It  is  rarely  used  by  homicides,  but  frequently  by  suicides,  and 

1  Coster's  Rat  and  Roach  Exterminator  contains  2.13  per  cent,  of  phosphorus, 
and  though  the  buyer  is  assured  by  the  label  that  it  is  "not  poisonous, "  2  fatal  cases 
have  been  reported  from  taking  it.  Parson  and  Co.'s  Vermin  Exterminator  has  0.4 
per  cent,  of  free  phosphorus. 


PHOSPHORUS  179 

sometimes  children  ignorantly  eat  the  paste  or  suck  the  heads  of 
matches.  More  than  half  the  death  cases  are  children.  Of  the 
adults,  nearly  all  are  suicidal,  a  few  only  being  accidental  and 
none  criminal.  In  spite  of  the  garlicky  taste  and  smell,  it  could 
be  given  in  coffee,  the  more  easily  if  at  the  same  meal  onions  or 
garlic  had  been  eaten. 

Symptoms. — If  the  phosphorus  be  taken  in  lumps,  the  effect  is 
not  proportionate  to  the  weight.  To  be  fully  effectual  it  must 
be  dissolved  or  finely  divided,  as  it  is  in  the  rat-pastes  and  pill- 
masses. 

The  cases  of  poisoning  are  often  referred  by  their  symptoms 
to  one  of  the  three  classes  established  by  the  researches  of  Tar- 
dieu — a  common  form,  showing  symptoms  of  local  irritation  and 
jaundice;  a  hemorrhagic  form  like  scurvy,  in  which  jaundice  and 
effusions  of  blood  occur;  and  a  nervous  form,  in  which  jaundice 
is  accompanied  by  creeping  sensations,  cramps,  drowsiness,  delir- 
ium, and  convulsions. 

Nearly  90  per  cent,  of  the  cases  suffer  from  acute  irritation 
followed  by  jaundice  and  profound  blood  changes.  Complaint  is 
made  that  the  substance  taken  had  the  taste  and  odor  of  garlic. 
Sometimes  violent  pain  in  the  throat,  gullet,  and  stomach  is  ex- 
perienced immediately,  accompanied  by  vomiting  and  purging. 
The  breath  is  phosphorescent,  and  the  ejected  matters  may  be 
bloody,  garlicky  in  odor,  and  emit  light  when  stirred  in  a  shallow 
dish.  In  a  large  number  of  cases  there  is  an  interval  of  several 
hours  between  the  taking  of  the  poison  and  any  symptom  what- 
ever. 

Death  from  collapse  may  come  at  this  early  stage,  but  usually 
the  irritation  abates  and  jaundice  sets  in  after  a  period  of  com- 
parative comfort.  This  quiet  interval  usually  lasts  from  two  to 
three  days,  but  it  may  be  only  one  day  in  length  or  be  prolonged 
for  several  weeks.  The  jaundice  portends  more  or  less  profound 
blood  changes.  In  addition  to  the  general  effects  wrought  by  the 
biliary  matters  in  the  circulation  there  will  be  the  toxic  symp- 
toms, caused  by  the  presence  of  phosphorus  derivatives.  Given 
in  detail,  there  will  be  yellowness  of  skin  and  conjunctiva  and 
tenderness  over  the  liver,  with  an  increased  area  of  hepatic  dul- 
ness.  Headache,  insomnia,  and  itching  eruptions  of  the  skin  are 
common.  The  urine  is  saffron-yellow  or  olive-green  in  color  from 
the  presence  of  bile-pigments,  scanty,  albuminous,  bloody,  con- 
taining tube-casts  and  occasionally  leucin  and  tyrosin.  Extreme 
weakness  culminating  in  heart  failure  is  a  characteristic  due  to 
the  degenerations  of  the  muscular  tissue,  including  the  heart. 
These  stormy  signs  soon  culminate  in  delirium,  convulsions, 
coma,  syncope,  and  death. 


l8o  NON-METALS 

In  a  certain  proportion  of  cases,  not  necessarily  fatal,  the  toxic 
effects  on  the  blood  and  its  vessels  are  made  conspicuous  by  the 
hemorrhages  which  accompany  the  jaundice.  Blood  may  be 
effused  under  the  skin  in  spots  or  pass  out  by  one  or  more  of 
the  mucous  channels.  Hemorrhage  has  occurred  from  the  nose, 
mouth,  bowels,  kidneys,  and  bladder  all  at  once.  Women  will 
have  uterine  hemorrhage,  and  if  pregnant,  will  abort,  with  alarm- 
ing flooding.  Anemia  and  exhaustion  reach  an  extreme  stage, 
and  delirium  ending  in  death  may  supervene  after  months  have 
elapsed  since  the  administration  of  the  poison.  Even  when  the 
direct  influence  of  the  poison  has  passed  away  and  life  is  no  longer 
threatened,  there  may  be  persistent  debility  and  local  palsies. 

The  rarest  form  of  acute  poisoning  is  that  in  which  the  nervous 
phenomena  are  the  most  conspicuous.  This  form  is  likely  to 
occur  when  the  case  is  one  of  inhalation  of  fatal  quantities  of 
phosphorus  vapor.  In  the  preparation  of  "  rat-paste,"  or  in  the 
making  of  matches,  the  materials  may  be  accidentally  heated  so 
as  suddenly  to  evolve  large  quantities  of  phosphorus  vapor.  The 
effects  are  fainting  attacks,  succeeded  by  profound  prostration 
with  extreme  muscular  weakness. 

Emphasis  must  be  laid  upon  the  variety  of  symptoms,  permit- 
ting of  many  different  clinical  pictures  and  also  upon  their  insidi- 
ous development.  There  can  be  but  little  doubt  that  at  one  time 
many  cases  were  incorrectly  diagnosed  as  acute  yellow  atrophy 
of  the  liver.  This  is  not  surprising,  as  the  history  of  the  case 
after  the  liver  symptoms  appear  is  the  same  as  in  acute  yellow 
atrophy,  even  to  the  contraction  of  the  organ  itself.  In  a  very 
small  proportion  of  cases  surviving  a  week  jaundice  does  not 
occur.  Casper  reports  a  case  that  lived  for  twelve  hours,  the 
only  marked  symptoms  being  one  act  of  vomiting  and  a  garlicky 
odor  of  the  breath,  which  was  luminous  in  the  dark. 

Fatal  Dose. — In  the  treatment  of  nervous  diseases  the  usual 
dose  is  -5^  gr-  (0.0013  gm.)  thrice  daily,  but  some  persons  can 
bear  gradual  increase  to  as  much  as  J  gr.  (0.016  gm.).  It  would 
be  risky  to  begin  with  these  maximum  quantities,  as  the  subjects 
of  nervous  diseases  are  usually  very  susceptible.  A  lunatic  died 
from  the  effects  of  0.0116  gm.  (less  than  •§-  gr.). 

A  healthy  adult  would  have  his  life  put  in  jeopardy  from  i  gr. 
taken  in  a  finely  divided  form,  such  as  the  pill,  paste,  or  the  match- 
head.  A  child  is  reported  to  have  died  from  sucking  the  heads 
of  two  matches,  containing  about  -^  gr.  of  phosphorus.  On  the 
other  hand,  there  has  been  recovery  after  ten  packages  had  been 
sucked. 

Fatal  Period. — Death  has  occurred  in  less  than  one  hour,  but 
the  duration  of  life  is  very  diverse  in  different  cases.  Some  die 


PHOSPHORUS  l8l 

in  four  hours;  three-fourths  of  the  cases  die  within  a  week;  some 
cases  become  chronic,  the  patient  dying  a  lingering  death  after 
many  months. 

Treatment. — In  considering  the  best  remedial  procedures  it 
must  be  noted  that  great  differences  have  been  observed  in  the 
time  of  onset  of  the  symptoms.  In  the  majority  they  commence 
after  an  interval  of  from  two  to  six  hours;  in  a  few  they  are  de- 
scribed as  immediate;  in  four-fifths  they  come  on  within  six  hours. 
In  every  case  presenting  a  history  of  a  poisonous  dose  the  treat- 
ment should  be  instituted  at  once,  instead  of  waiting  for  the  symp- 
toms to  appear.  There  is  need  for  instant  evacuation  by  the 
stomach-tube,  and  washing  out  of  the  stomach  with  a  solution 
of  potassium  permanganate  of  the  strength  of  0.5  to  i  per  cent, 
(about  4  gr.  to  i  fl.  oz.),  leaving  about  a  pint  in  the  stomach. 
This  antidote  has  a  chemical  reaction  with  the  phosphorus,  by 
which  the  latter  is  said  to  be  changed  to  harmless  compounds. 
Potassium  permangante  oxidizes  the  phosphorus,  forming  phos- 
phoric acid  and  phosphates,  itself  changing  to  manganese  dioxid. 
In  the  absence  of  a  stomach-tube  the  antidote  should  be  given — 
4  gr.  in  i  oz.  of  water — frequently  repeated.  The  permanganate 
is  in  part  reduced  by  the  organic  substances  of  the  food,  and  hence 
the  necessity  of  giving  it  in  excess,  although  in  a  dilute  solution  to 
avoid  gastric  irritation.  Diluted  hydrogen  peroxid  (1-3  per  cent.) 
as  an  oxidizing  agent  is  used  for  the  same  purpose  as  the  potas- 
sium permanganate  and  is  more  uniformly  beneficial.  Perhaps 
the  most  efficient  oxidizing  antidote  is  a  mixture  of  the  two  accord- 
ing to  the  method  given  (p.  88,  foot-note). 

Copper  sulphate  is  often  recommended  as  an  antidote.  When 
its  solution  is  mixed  with  phosphorus  in  a  test-tube,  the  phos- 
phorus is  seen  to  change  instantly  to  black  copper  phosphid, 
which  is  not  injurious.  There  is  one  drawback  to  its  use.  In  the 
quantities  recommended  and  needed  for  full  antidotal  effect  (3  gr. 
frequently  repeated)  the  copper  salt  is  a  decided  irritant  and  is 
likely  to  aggravate  the  gastro-enteritis  or  set  up  a  violent  one  of 
its  own. 

Another  antidote  honored  by  text-book  commendation  is  tur- 
pentine. It  is  said  to  combine  with  the  phosphorus  to  produce 
phosphoroterebinthinic  acid,  a  non-poisonous  solid.  To  be  effi- 
cient the  article  must  be  an  old  acid  sample,  and  some  enjoin  that 
the  French  article  alone  is  of  any  value.  As  old  French  turpen- 
tine is  not  the  kind  kept  officially  by  druggists,  it  is  practically 
out  of  the  question. 

After  potassium  permanganate  or  hydrogen  peroxid  has  been 
freely  used  for  the  phosphorus  in  the  stomach,  evacuation  of  the 
bowels  should  be  secured  by  the  use  of  some  old  turpentine  that 


182  NON-METALS 

has  been  kept  for  a  long  time  on  the  shelf  in  doses  of  J  fl.  dr. 
(1.90  c.c.),  given  in  an  emulsion  with  mucilage  every  half  hour. 
As  the  phosphorus  tends  to  adhere  to  the  mucous  folds  of  the 
small  intestine  it  is  advisable  to  maintain  purgation  by  giving  the 
turpentine  for  several  days. 

Postmortem  Appearances.— The  general  toxic  effect  of  phos- 
phorus is  to  induce  a  wide-spread  degeneration  of  glandular  and 
muscular  tissue.  This  degeneration  consists  in  the  formation  of 
fat  in  place  of  the  true  cellular  tissue.  It  is  presumable  that  those 
cases  of  death  in  which  no  change  has  been  found  postmortem 
would  have  yielded  a  different  report  if  the  microscope  had  been 
used  to  aid  the  naked  eye.  The  stomach  may  be  free  from  signs  of 
disease,  although,  as  a  rule,  there  will  be  a  fatty  degeneration  of 
the  epithelial  cells,  with  thickening  of  the  mucous  membrane,  due 
to  enlargement  of  the  glands  and  an  occlusion  by  large  granular 
cells.  This  condition  obtains  in  the  intestines  and  is  often  asso- 
ciated with  hemorrhagic  foci  and  minute  inflamed  areas.  These 
appearances  are  found  also  in  diseases  due  to  septic  conditions  of 
the  blood. 

Even  at  an  early  period  the  liver  is  the  seat  of  fatty  degenera- 
tion. If  seen  early,  it  may  be  enlarged,  yellow,  deficient  in  blood, 
and  present  a  mottled  section.  Under  the  microscope  the  hepatic 
cells  are  found  to  lack  definition  and  to  be  granular  or  filled  with 
large  fat-globules.  When  death  follows  a  chronic  history,  the 
liver  may  be  found  atrophied  and  the  changes  more  profound. 

The  capsule  of  the  kidney  is  easily  stripped.  Under  it  are 
found  hemorrhagic  patches.  The  organ  itself  is  enlarged,  and 
its  epithelial  cells  and  vascular  walls  are  infiltrated  with  granular 
fat. 

The  transverse  stripes  of  the  muscular  fibers  of  the  heart  are 
replaced  by  fat,  a  form  of  change  seen  in  the  muscular  system 
generally.  If  the  case  has  been  one  of  the  hemorrhagic  type, 
there  will  be  extravasations  of  blood  in  the  tubules  of  the  kidney, 
in  the  endocardium,  the  peritoneum,  the  pleura,  the  mediastinum, 
and  many  other  places. 

Chronic  Poisoning.— Weakly  individuals  working  daily  with 
ordinary  yellow  phosphorus  itself,  or  even  its  less  poisonous 
compound,  phosphorus  sulphid,  as  in  match  factories,  become  the 
subjects  of."lucifer  disease"  or  " phosphorus  necrosis."  After 
several  weeks  or  months  obstinate  toothache  is  felt,  and  when  the 
tooth  is  extracted  the  gum  does  not  heal,  but  retracts,  leaving  a 
suppurating  bony  surface.  Pieces  of  bone  come  away,  and  the 
disease-process  in  the  marrow  and  in  the  periosteum  spreads  to 
new  areas,  other  teeth  and  their  sockets  become  involved,  and 
greater  portions  of  bone  necrosed.  Accompanying  the  local 


PHOSPHORUS 


mischief,  partly  caused  by  it  and  also  aggravating  it,  is  a  general 
disturbance  of  health  characterized  by  anemia,  pallor,  weakness, 
hectic  fever,  diarrhea,  septicemia,  purpura,  sometimes  ending  in 
death  by  exhaustion.  These  symptoms  may  be  prevented  by 
dental  inspection  of  workmen  and  rilling  of  all  carious  spots  on  the 
teeth,  by  the  circulation  of  fresh  air,  by  the  frequent  and  sys- 
tematic use  of  mouth-washes  of  sodium  bicarbonate,  and  by 
the  prompt  exclusion  of  any  one  showing  significant  symptoms. 

The  use  of  " safety-matches"  and  varieties  substituting  the  red 
or  non-poisonous  form  is  spreading,  and,  with  better  hygienic 
measures,  bids  fair  to  remove  "phossy  jaw"  from  the  bills  of  mor- 
tality. Match  making  with  yellow  phosphorus  should  be  unlawful. 

Tests. — The  tests  for  phosphorus  are  its  peculiar  odor,  its 
luminous  appearance  in  the  dark,  and  the  power  of  reduction 
possessed  by  it  over  silver  nitrate. 

Detection. — The  garlicky  odor  is  sus- 
picious, but  may  be  masked  by  articles  of 
food  having  a  similar  odor,  such  as  onions. 
If  the  room  be  darkened,  the  breath  will 
shine  faintly  and  phosphorescent  spots  will 
be  seen  upon  the  lips  or  clothing.  The 
vomited  matters  or  the  urine,  if  put  into  a 
test-tube,  acidulated  with  sulphuric  acid, 
and  gently  heated,  will  evolve  luminous 
fumes.  A  piece  of  white  paper  molded  as 
a  lid  to  the  tube  (Fig.  55)  should  be  wet 
with  a  drop  of  a  strong  solution  of  silver 
nitrate.  The  phosphorus  vapor  will  cause 
the  metallic  silver  to  be  reduced  as  a  black 
spot  on  the  paper.  To  prove  that  this  is 
not  produced  by  hydrogen  sulphid,  the 
same  test  should  be  repeated  after  adding 
some  lead  acetate  to  fix  the  hydrogen  sul- 
phid in  the  liquid,  or  a  plug  of  absorbent 
cotton  wet  with  lead  acetate  may  be  put 
in  the  neck  of  the  tube.  •  When  the  phos- 
phorus is  present  in  minute  quantities,  it 
will  not  be  evident  by  this  test  unless  per- 
formed by  the  careful  method  of  Mitscher- 
lich. 

Mitscherlich's  Test. — The  suspected  material  is  put  into 
a  flask  (c,  Fig.  56)  and  acidulated  with  sulphuric  acid  to  prevent  the 
escape  of  ammoniacal  vapors.  When  heated  gradually  by  the 
sand-bath  the  phosphorus  vaporizes,  and  is  conducted  by  a  long 
delivery  tube  to  a  glass  Liebig  condenser,  d,  kept  cold  by  water 


FIG.  55. — Apparatus  for 
testing  phosphorus  vapor  with 
silver  nitrate. 


i84 


NON-METALS 


circulating  around  the  inner  tube.  The  room  being  totally  dark, 
flashes  of  light  and  shining  clouds  appear  in  the  inner  tube  at  the 
point  where  the  phosphorus  vapors  are  condensed  by  their  cold 
surroundings.  The  odor  of  the  distillate  is  alliaceous. 

The  tube  being  vertical,  the  condensed  phosphorus  will  pass 
down  into  a  receiver,  e,  where  it  may  be  converted  to  phosphoric 
acid  by  the  action  of  nitric  acid.  The  phosphoric  acid  precipitated 
by  magnesian  mixture,  collected,  ignited,  and  weighed,  will  deter- 
mine the  quantity  of  phosphorus. 

If  no  luminosity  has  been  observed  after  distilling  one-third  of 
the  material,  the  remainder  may  be  subjected  to  a  more  searching 
test.  The  end  of  the  exit  tube  of  the  flask  should  be  detached 


FIG.  56.— Mitscherlich's  test  for  phosphorus:    a,  Generator  for  COa;  b,  wash-bottle;  c,  suspected 
material;  d,  condenser;  e,  receiver  for  distillate. 

from  the  condenser  at  d,  and  immersed  in  a  solution  of  silver  nitrate. 
The  contents  of  the  flask,  c,  are  again  heated,  while  a  continuous 
current  of  carbon  dioxid  from  the  generator,  a,  washed  in  b, 
passes  through,  slowly  carrying  the  phosphorus  unoxidized  into 
the  silver  nitrate,  precipitating  black  silver  phosphid,  and  leaving 
some  phosphoric  acid  in  solution.  Should  no  black  deposit  appear, 
the  phosphorus  may  be  assumed  to  be  absent.  The  silver  phosphid 
collected  on  a  filter  and  washed  is  suspended  in  water,  and  intro- 
duced into  the  hydrogen  apparatus  employed  in  the  phosphin  test 
described  below.  The  greenish  flame  is  seen  even  when  the 
quantity  is  very  minute. 

Fallacies. — Deductions  based  upon  the  detection  of  phosphoric 


PHOSPHORUS  185 

acid  in  the  distillate  when  luminosity  and  free  phosphorus  have 
not  been  obtained  may  be  erroneous.  The  phosphoric  acid  may 
have  been  brought  over  by  mechanical  action. 

Interferences. — It  can  be  performed  in  an  organic  mixture,  but 
not  in  the  presence  of  certain  chemicals,  such  as  iodin,  calomel, 
and  corrosive  sublimate.  The  light  will  not  show  in  the  vapor 
of  turpentine,  which  may  have  been  given  as  an  antidote.  It  is 
not  perceived,  should  alcoholic  or  ethereal  vapors  arise  from  the 
same  mixture.  Ammonia,  chlorin,  hydrogen  sulphid,  sulphur 
dioxid,  petroleum,  creasote,  and  most  essential  oils  interfere  with 
the  phosphorescence. 

Delicacy. — This  test  is  extremely  sensitive,  having  yielded  un- 
mistakable evidence  from  -^  gr.  of  phosphorus  diffused  in  3  oz. 
of  fluid  (i  :  200,000). 

The  Phosphin  Test. — Having  set  up  the  usual  hydrogen-gener- 
ating apparatus — that  is,  flask,  pure  zinc,  and  dilute  sulphuric 
acid — the  gas  is  delivered  by  a  three-way  tube,  having  a  side  jet, 


FIG.  57. — The  bands  represent  the  green  lines  of  the  spectrum  of  burning  phosphin.     They  are  between 
the  lines  D  and  E  of  the  solar  spectrum  (Boisbaudran). 

to  a  wash  flask  containing  the  suspected  organic  mixture,  and 
gently  heated.  The  nascent  hydrogen  acting  on  the  phosphorus, 
phosphids,  or  its  lower  oxids  in  the  mixture  will  form  phosphin 
(PH3),  a  gas  which  will  escape  from  the  heated  flask  by  a  tube 
drawn  out  to  a  jet  and  having  a  platinum  tip.  When  lighted,  the 
phosphin,  if  not  too  concentrated,  will  burn  with  a  characteristic 
green  color.  It  may  be  contrasted  with  the  flame  from  the  side 
jet,  which  should  be  the  pale-blue  hue  of  pure  hydrogen.  If  this 
side  jet  is  greenish,  there  must  have  been  some  phosphorus  in 
the  zinc  of  the  generator.  To  make  sure,  the  greenish  flame 
should  be  studied  with  the  spectroscope.  If  due  to  phosphorus, 
it  will  show  one  orange  band  between  C  and  D,  and  several  green 
bands  (Fig.  57).  Both  the  color  of  the  flame  and  its  spectrum 
are  best  developed  if  the  temperature  of  the  flame  is  not  allowed 
to  rise  too  high.  This  may  be  accomplished  conveniently  by 
allowing  the  flame  to  impinge  against  the  bottom  of  a  porcelain 
dish  filled  with  cold  water,  or  by  wrapping  the  burner  with  a 
small  strip  of  cloth  saturated  with  cold  water. 


i86 


NON-METALS 


Phosphorescence  in  Hydrogen.— This  test  for  free  phosphorus 
only  is  best  performed  with  the  apparatus  of  Mukerji  (Fig.  58), 
made*  from  a  three-necked  Woulfe's  bottle  of  i -liter  capacity,  by 
inserting  through  close-fitting  stoppers  a  long  safety  funnel  tube 
(a)  in  one  side-neck,  and  a  short  jet  tube  (c)  in  the  other.  Through 
a  loose-fitting  one  at  the  middle  neck  rises  a  tube  n  in.  long 
and  J  in.  in  diameter,  which  is  closed  above  by  a  cork  (b).  From 
zinc  and  dilute  sulphuric  acid  in  the  bottle  hydrogen  is  evolved. 
Observed  in  the  dark,  the  gas  at  the  jet  should  emit  no  glow,  even 
if  commercial  chemicals  are  used.  When  the  chemical  action  has 
heated  the  bottle,  the  suspected  material  is  introduced  through  the 
middle  tube  or  through  either  neck,  quickly  closing  again  with 
the  stopper. 

Free  phosphorus  is  vaporized  and  glows  in  a  sheaf  of  light  at 
3  the  jet.     If  the  middle  cork  is  removed, 

the  light  sinks  down  through  the  jet  into 
the  bottle,  and  the  glow  appears  at  the 
outer  opening  of  the  middle  tube. 

Replacing  the  cork  causes  the  glow 
to  reappear  at  the  jet.  If  a  quantitative 
estimate  is  desired,  a  proper  delivery  tube 
may  be  substituted  for  the  jet  and  the  gas 
passed  into  silver  nitrate. 

Special  Advantages. — The  apparatus 
is  simple,  and  as  no  lamp  is  required  for 
distillation,  complete  darkness  is  possi- 
ble. The  amount  of  air  entering  by  the 
jet  tube  is  so  small  in  comparison  with 
the  quantity  of  hydrogen  continuously 
evolved  that  the  mixture  is  never  explo- 
sive. Before  taking  apart,  the  apparatus 
should  be  filled  with  water  by  the  funnel 
tube. 

While  this  test  gives  a  glow  with  free 
phosphorus  only,  and  not  with  any  of 
its  compounds,  the  phosphin  test  gives  a 
green  flame  on  ignition  of  the  gas  when 
the  materials  contain  phosphorus,  phos- 
phids,  phosphites,  or  hypophosphites  in- 
differently. Free  phosphorus  does  not 
unite  with  free  hydrogen,  and  the  gas  here  is  not  phosphin. 

Interferences. — Turpentine  or  ether  will  prevent  the  glow  in 
this  test.  It  can  be  performed  in  the  presence  of  organic  matter, 
alcohol,  iodin,  hydrogen  sulphid,  and  many  other  substances  that 
prevent  the  glow  in  Mitscherlich's  test. 


FIG.   58. — Phosphorescence  in  hy- 
drogen. 


PHOSPHORUS  187 

Delicacy. — Mukerji  found  the  test  as  sensitive  as  that  of  Mitsch- 
erlich,  getting  appreciable  effects  from  i  :  200,000. 

Quantitative  Estimation. — Sonnenschein's  method  for  free 
phosphorus  is  first  to  estimate  the  phosphoric  acid  by  diluting  the 
suspected  mixture,  filtering  a  measured  fraction,  and  precipitating 
with  magnesian  mixture,  estimating  as  ammoniomagnesian  phos- 
phate. Another  portion  treated  on  a  water-bath  with  potassium 
chlorate  and  hydrochloric  acid  will  have  its  free  phosphorus 
oxidized  to  phosphoric  acid.  This,  being  estimated,  will  show 
an  excess  over  the  first  portion.  The  excess  is  then  to  be  calcu- 
lated as  free  phosphorus. 

Period  for  Postmortem  Recognition. — Tested  by  Mitsch- 
erlich's  method,  characteristic  phosphorescence  has  been  obtained 
in  putrid  organs  two  months  after  death  and  burial.  There  has 
been  failure,  however,  to  detect  the  poison  even  a  few  days  after 
death,  because  of  the  conversion  of  the  phosphorus  into  ammo- 
niomagnesian phosphate  or  some  other  salt  of  no  medicolegal 
interest. 

Phosphorus  and  hydrogen  form  three  compounds,  to  all 
of  which  the  name  phosphoretted  hydrogen  is  applied,  namely: 
PH3,  at  ordinary  temperatures  a  gas;  PH2,  a  liquid;  and  P2H, 
a  solid. 

Phosphin  (PH3). — Phosphorus  terhydrid  or  gaseous  phosphor- 
etted hydrogen  when  inhaled  is  a  very  poisonous  gas,  reducing 
the  oxyhemoglobin  of  the  blood.  It  can  be  made  by  boiling 
phosphorus  with  strong  potash  or  soda  lye,  or  by  generating 
hydrogen  in  the  presence  of  the  lower  oxids  of  phosphorus. 

3KOH     +     4P     +     3H20  3KH2P02     +     PH3. 

Potassium  hypophosphite. 

It  is  colorless,  smells  putrid,  and,  as  ordinarily  made,  it  con- 
tains another  hydrid,  PH2,  which  causes  it  to  inflame  spontane- 
ously on  contact  with  the  air.  When  evolved  with  hydrogen 
it  burns  with  a  greenish  flame,  but  if  dry  and  insufficiently  sup- 
plied with  air,  the  flame  is  white.  When  passed  through  a  solu- 
tion of  silver  nitrate,  the  silver  is  deposited  as  metal,  leaving  nitric 
and  phosphoric  acids  in  solution;  by  adding  excess  of  molybdic 
acid  the  phosphoric  acid  can  be  detected. 

Phosphorus  and  Oxygen. — When  phosphorus  burns  in  air 
it  forms  phosphorus  pentoxid,  P2O5.  When  the  oxidation  is  incom- 
plete three  other  compounds  are  made,  thus:  P2O4,  the  tetroxid; 
P2O3,  the  trioxid;  P4O,  the  suboxid. 

Phosphorus  pentoxid,  or  phosphoric  anhydrid,  is  a  white 
compound  remarkable  for  its  power  of  combining  with  water. 


j88  NON-METALS 

When  its  combining  powers  with  water  are  fully  satisfied,  phos- 
phoric acid  results: 

P205       +        3H20       =         2H3P04 

Phosphoric  acid. 

When  the  trioxid  unites  with  water  it  forms  phosphorous  acid: 
P203       +       3H20       =       2H3P03 

Phosphorous  acid. 

Phosphoric  acid  (H3PO4),  or  orthophosphoric  acid,  is  the 

common  acid  used  in  medicine  under  the  name  acidum  phos- 
phoricum.  The  dilute  official  acid  is  made  by  mixing  the  strong 
with  a  sufficient  quantity  of  water  to  make  a  10  per  cent.  acid. 
The  strong  acid  can  be  made  by  dissolving  the  pentoxid  in  water,  or 
by  the  direct  oxidation  of  phosphorus  with  strong  nitric  acid.  The 
phosphates  of  the  soils  and  of  the  animal  and  vegetable  tissues  are 
its  salts. 

Properties. — It  is  a  non-corrosive,  viscous  liquid,  colorless, 
odorless,  with  a  pleasantly  sour  taste.  It  crystallizes  with  diffi- 
culty, when  heated  loses  water,  and  at  low  redness  volatilizes.  It 
is  a  tribasic  acid,  forming  three  classes  of  salts,  with  a  univalent 
metal.  The  point  of  transition  as  shown  by  litmus  from  acid  to 
neutral  reactions  is  not  sharp  when  sodium  hydroxid  is  added  to 
dilute  phosphoric  acid.  The  alkaline  indication  appears  before 
two  hydrogen  atoms  are  replaced.  The  alkalinity  gradually 
increases  until  all  the  hydrogen  has  been  replaced  by  the  metal, 
and  the  normal  salt  produced  is  decidedly  basic  in  reaction.  The 
three  salts  possible  with  sodium  are: 

Na3PO4,  normal,  tertiary,  or  trisodium  phosphate.  It  is  an 
unstable  and  basic  compound,  alkaline  in  reaction. 

Na2HPO4,  secondary  or  disodium  phosphate.  Though  retain- 
ing some  acid  hydrogen,  yet  this  phosphate  is  feebly  alkaline.  It 
exists  in  the  blood  and  is  permanent. 

NaH2PO4,  acid,  primary,  or  monosodium  phosphate.  It  gives 
the  acid  reaction  to  urine. 

The  peculiar  reactions  to  litmus  shown  by  these  salts  are  due 
to  the  difference  in  dissociation  of  the  three  hydrogen  atoms.  Per- 
fect breaking  down  of  H3PO4  into  H',  H',  H'  (PO4)'"  does  not 
occur  all  at  once  in  aqueous  solution,  nor  readily  at  any  time. 
While  it  does  come  eventually,  the  hydrogen  ions,  like  those  of 
other  weak  acids,  are  not  completely  dissociated  in  the  beginning. 
The  first  ions  of  H3PO4  dissociate  easily  as  H'  and  (H2PO4)'. 
When  the  base  sodium  hydroxid  is  added  to  it  the  H*  is  removed, 
the  second  dissociation  sets  in,  and  the  (H2PO4)'  breaks  down  into 
H*  and  (HPO4)".  Further  dilution  or  the  action  of  more  base 


PHOSPHORUS  189 

separates  the  anion  (HPO4)"  into  H*  and  (PO4)'".  This  complete 
electrolytic  dissociation  is  so  slight  that  the  water  comes  into  play 
as  it  does  with  the  other  weak  acids,  and  hydrolytic  dissociation 
occurs,  causing  a  different  group  of  ions.  In  watery  solution  the 
interaction  causes  the  normal  sodium  phosphate  to  break  down  in 
the  manner  indicated  by  the  following  equation: 

Na3P04    +    H20    ==    Na-,  Na-,  (HPO4)"   +   Na-,(HO)'. 

The  hydroxidion  (HO)'  thus  liberated  as  a  result  of  the  two  dis- 
sociations is  the  cause  of  the  alkaline  reaction  of  Na3PO4.  The 
secondary  phosphate,  Na2HPO4,  in  water  undergoes  some  degree 
of  hydrolysis,  and  therefore  gives  a  feebly  alkaline  reaction.  With 
monad  and  dyad  bases  phosphoric  acid  forms  double  salts,  such 
as  ammoniomagnesian  phosphate,  NH4MgPO4,  found  in  stale 
urine,  and  potassiobarium  phosphate,  KBaPO4. 

Tests  for  Phosphoric  Acid  and  Phosphates.  —  (i)  The  phosphates 
are  precipitated  as  white  ammoniomagnesian  phosphate  by  mag- 
nesia mixture  (containing  magnesium  sulphate,  ammonium  chlo- 
rid,  and  ammonium  hydroxid): 


Ammoniomagnesian          Ammonium 
phosphate.  sulphate. 

(2)  Ammonium   silver   nitrate  throws   down   a   yellow   precipi- 
tate of  silver  phosphate  which  is  soluble  in  ammonia  and  nitric 
acid: 

H3P04    +    3(AgN03,  NH3)    =    Ag3PO4    +    3NH4NO3. 

(3)  An  excess  of  solution  of  ammonium  molybdate  in  dilute 
nitric  acid  will  precipitate  the  phosphoric  acid  if  heated  gently: 
the  yellow  precipitate  is  phosphomolybdate  of  ammonium. 

(NH4)3P04,   ioMo03,   2H20, 

which  dissolves  easily  in  ammonia-water.  This  test,  unlike  (i) 
and  (2),  can  be  used  in  acid  solution  and  is  the  most  delicate. 

Incompatibles  oj  Acidum  Phosphoricum.  —  It  is  incompatible 
with  silver  nitrate,  ferric  chlorid,  lead  acetate,  and  solutions  of 
soluble  iron  phosphate  or  pyrophosphate.  Dose  3  to  7  HI  (0.20- 
0.66  gm.). 

Metaphosphoric  Acid  (HPO3).  —  Properties.  —  A  transparent 
glassy  mass,  known  as  glacial  phosphoric  acid.  It  is  a  monobasic 
acid. 

Preparation.  —  Metaphosphoric    acid    is    formed    when    ortho- 


190  NON-METALS 

phosphoric   acid  is  heated  higher  than   is   necessary   to   produce 
pyrophosphoric. 

Upon  the  addition  of  water  to  this  glacial  acid,  a  solution  is 
obtained,  which,  upon  boiling,  is  converted  into  the  tribasic  phos- 
phoric acid,  H3PO4. 

It  is  detected  by  the  precipitation  of  its  barium  salt  as  a  white 
solid.  A  mixture  of  albumin  with  acetic  acid  gives  a  white  pre- 
cipitate to  its  solution. 

Pyrophosphoric  Acid  (H4P2O7). — Properties. — It  can  be  ob- 
tained as  crystals  by  evaporation  in  vacua.  It  is  tetrabasic. 

Preparation. — Pyrophosphoric  acid  is  prepared  (i)  by  heating 
the  tribasic  phosphoric  acid,  H3PO4,  to  213°  C.  (415.4°  F.). 
Thus: 

2H3PO4  H2O          +         H4P2O7 

Water.  Pyrophosphoric  acid. 

(2)  By  the  action  of  hydrogen  sulphid,  H2S,  on  pyrophosphate 
of  silver,  Ag4P2O7.  Thus: 

Ag4P207       +       2H2S      =       2Ag2S       +      H4P207 

Sulphid  of  silver.        Pyrophosphoric  acid. 

It  is  identified  by  the  white  precipitate  falling  upon  the  addition 
of  silver  nitrate,  but  no  precipitate  is  caused  by  albumin  and  acetic 
acid. 

The  three  acids  above  described  may  be  prepared  by  acting 
upon  phosphorus  pentoxid,  P2O5,  with  different  proportions  of 
water,  as  follows: 

P2O5  -f-  H2O    =  2HPO3,    Metaphosphoric  acid,  monobasic. 
P2O5  -j-  2H2O  =  H4P2O7,   Pyrophosphoric  acid,  tetrabasic. 
P2O5  -j-  3H2O  =  2H3PO4,  Orthophosphoric  acid,  tribasic. 

By  heating  to  300°  C.  (572°  F.)  the  tribasic  phosphoric  acid, 
2H3PO4,  and  thus  driving  off  a  molecule  of  water,  we  can  obtain  the 
pyrophosphoric  acid,  H4P2O7,  and  by  the  action  of  heat  to  400°  C. 
(752°  F.)  upon  this,  with  the  loss  of  another  molecule  of  water,  we 
obtain  the  metaphosphoric  acid,  2HPO3. 

Phosphorous  Acid  (H3PO3). — Properties. — It  forms  deliques- 
cent crystals  which  readily  decompose;  throws  down  gold,  silver, 
and  platinum  from  their  solutions.  As  a  colorless  acid  liquid  it  is 
dibasic,  only  2  H  atoms  will  ionize,  as  in  the  formula  H',  H*, 
(HPO3)".  It  is  a  strong  deoxidizer,  uniting  with  oxygen  to  form 
phosphoric  acid.  Its  salts  are  called  phosphites. 

Preparation. — Phosphorous  acid  is  formed  by  acting  r  xm  the 
trichlorid  of  phosphorus,  PC13,  with  water,  H2O.  Thus: 

PC13       +       3H20       =       3HC1       +       H3P03. 


CARBONIC    ACID  IQI 

Hypophosphorous  Acid  (H3PO2). — Properties. — An  acid,  syrupy 
fluid,  is  official,  containing  30  per  cent,  of  absolute  acid.  All  the 
hypophosphites  are  soluble  in  water.  It  is  a  white  crystalline  sub- 
stance, having  but  one  atom  of  replaceable  hydrogen.  This  may  be 
expressed  by  writing  it  as  H',(PO2H2)'.  The  other  hydrogen  atoms 
have  no  acid  quality  and  will  not  ionize. 

Preparation. — This  acid  is  prepared  by  acting  upon  barium 
hypophosphite,  Ba(H2PO2)2,  with  sulphuric  acid,  H2SO4.  Thus: 

Ba(H2PO2)2     +     H2SO4     =     BaSO4     +     2H3PO2. 

Acidum  hypophosphorosum  dilutum  contains  10  per  cent. 
H3PO2.  Dose  10  to  60  Tit  (0.66-4.00  gm.). 

Phosphorus  with  chlorin  forms  two  compounds,  viz.:  PC13, 
phosphorus  trichlorid;  PC15,  phosphorus  pentachlorid. 

Phosphorus  trichlorid,  PC13,  is  a  colorless,  volatile,  strongly 
fuming  liquid,  and  is  formed  by  passing  chlorin  gas  over  phos- 
phorus. It  gradually  decomposes  into  hydrochloric  acid  and 
phosphorous  acid.  It  may  also  be  formed  by  the  combustion  of 
phosphorus  in  chlorin  gas. 

Phosphorus  pentachlorid,  PC15,  is  a  solid  crystalline  substance, 
and  decomposes  by  excess  of  water  into  hydrochloric  acid,  HC1, 
and  tribasic  phosphoric  acid,  H3PO4.  It  is  prepared  by  passing 
excess  of  chlorin  through  the  phosphorus  trichlorid.  Should  water 
be  present  only  in  limited  quantity,  a  liquid  called  phosphoric 
oxychlorid,  PC13O,  is  formed.  Thus: 

PC15        +        H20  2HC1        +        PC130. 

Phosphorus  forms  with  iodin  PI3  and  PI5,  with  bromin  PBr3 
and  PBr5,  and  it  burns  spontaneously  in  those  substances  when 
they  are  in  the  gaseous  state.  By  the  action  of  sulphuretted  hy- 
drogen, H2S,  upon  phosphorus  pentachlorid,  PC15,  a  substance 
termed  phosphoric  sulphochlorid,  PSC13,  is  obtained. 

Phosphorus  forms  several  compounds  with  sulphur,  two  of 
them,  P2S3  and  P2S5,  corresponding  in  composition  with  the  oxids 
P2O3  and  P2O,. 

CARBONIC  ACID 

Formula,  H2CO3.     Atomic  weight,  62. 

In  another  section  the  element  carbon  and  its  two  oxygen 
compounds,  carbon  monoxid  and  carbon  dioxid,  have  been  fully 
discusse^.  Mention  was  made  of  the  fact  that  when  dissolved  in 
water  ca¥bon  dioxid  became  carbonic  acid,  and  in  this  form  was 
widely  known  in  the  aerated  liquid  commonly  called  soda,  water. 
If  the  freshly  drawn  aerated  water  be  tested  before  much  gas 


1 92  NON-METALS 

escapes,  it  will  be  found  to  give  the  usual  red  reaction  with  litmus. 
The  gas  CO2,  like  SO2,  is  an  anhydrid,  converted  to  an  acid  by 
water;  H2CO3,  resembling  in  this  respect  H2SO3,  sulphurous 
acid.  Like  that  acid,  H2CO3  readily  decomposes  into  H2O  and 
the  anhydrid  CO2.  Carbonic  acid  is  a  weak  dibasic  acid.  It 
resembles  H2SO3  and  other  dibasic  acids — in  that  it  breaks  up 
into  two  different  anions,  first  into  the  univalent  (HCO3)',  and  next 
into  the  divalent  carbanion  (CO3)".  Being  a  very  weak  acid,  dis- 
sociation is  very  slight  indeed,  whether  it  be  at  the  first  stage, 
H2CO3  =  H*,  (HCO3)',  or  at  the  less  appreciable  second  (HCO3)' 
=  H',  (CO3)".  The  dominant  anion  appears  to  be  (HCO3)', 
the  solution  tending  to  form  this  group  by  preference. 

The  carbonates  are  very  abundant  in  nature,  among  them 
being  limestone,  marble,  and  chalk;  and  they  are  in  general  quite 
insoluble  in  water.  All  carbonates,  except  those  of  the  alkali 
metals,  are  of  difficult  solubility.  Both  the  normal  sodium  car- 
bonate, Na2CO3,  and  the  acid  salt,  NaHCO3,  have  an  alkaline 
reaction.  As  this  indicates  the  presence  of  hydroxidion  (HO)'  it 
appears  that  the  soluble  carbonates  are  hydrolyzed — that  is,  the 
ions  are  changed  by  interacting  with  the  water.  A  part,  at  least, 
of  this  hydrolysis  may  be  represented  by  the  following  equation: 

Na2C03     +     H20  Na-,  (HO)'     +     Na',  (HCO3)'. 

Obeying  its  tendency,  the  carbanion  (CO3)"  breaks  up  the  H2O 
to  form  the  ions  (HCO3)'  and  (HO)'.  A  small  amount  of  hydrox- 
idion is  sufficient  to  give  an  alkaline  reaction  to  solutions  of 
NaHCO3.  The  reactions  indicated  above  characterize  all  soluble 
carbonates. 

DERIVATIVES   OF   CARBONIC   ACID 

Beside  the  numerous  class  of  carbonates  in  which  the  hydro- 
gen only  is  replaced  by  metals,  there  are  important  compounds 
which  may  be  regarded  as  derived  from  carbonic  acid  by  replace- 
ment of  its  hydroxyls  in  CO(OH)2,  with  chlorin  and  with  amido- 
gen,  NH2.  The  two  most  important  are  carbonyl  chlorid,  COC12, 
and  carbonyl  diamid  or  urea,  CO(NH2)2. 

Carbonyl  Chlorid  (COC12)  (Carbon  Oxychlorid).—This  com- 
pound is  known  as  phosgene  gas  because  it  is  generated  by  the 
action  of  direct  sunlight  on  a  mixture  of  equal  proportions  of 
carbon  monoxid,  CO(carbonyl),  and  chlorin,  CO  +  C12=  COC12. 
The  same  reaction  occurs  by  catalysis  when  the  mixed  gases  are 
passed  over  charcoal  (p.  386). 

Properties. — Carbonyl  chlorid  is  a  gas  without  color,  but  with 
a  stifling  odor.  When  inhaled  it  is  a  suffocative  poison  (p.  388). 


DERIVATIVES    OF    CARBONIC    ACID  193 

In  the  presence  of  water  it  is  decomposed  with  the  formation  of 
carbonic  acid  and  hydrochloric  acid: 

COC12  +  2H2O  =  H2CO3  +  2HC1. 

Carbonic  Acid  Diamid.— The  most  significant  reaction  of 
carbonyl  chlorid  is  one  by  which  we  may  infer  the  constitution  of 
urea.  When  ammonia  is  permitted  to  act  on  COC12  there  is 
decomposition  of  the  carbonyl  chlorid  with  formation  of  ammo- 
nium chlorid  and  a  compound  containing  carbonyl  and  two  parts 
of  the  group  NH2,  characteristic  of  amids,  thus: 

COC12     +     4NH3     =      CO(NH2)2     -f      2NH4C1 

Ammonia.  Carbonyl  diamid.  Ammonium  chlorid. 

By  extracting  with  alcohol  the  carbonic  acid  diamid  is  separated 
from  the  insoluble  ammonium  chlorid,  and  on  evaporation  is  left 
as  colorless  crystals.  These  crystals  are  neutral  in  reaction, 
without  odor,  but  having  a  bitter  taste.  In  solution  they  have  no 
electroconductivity,  hence  are  non-electrolytes. 

This  substance  is  found  abundantly  in  the  body  and  urine  of 
carnivora,  and  is  known  commonly  as  urea. 

Carbon  Disulphid  (CS2).— The  relationship  of  carbon  dioxid, 

QTT 

CO2,  to  carbonic  acid,   CO</~TJ,  has  already  been  referred  to. 

\jt~i 

STT 

There  is  a  trithiocarbonic  acid,  CS<C<-TT,  in  which  all  the  oxygen 

has  been  replaced  by  sulphur,  and  it  has  a  corresponding  disulphid, 
CS2.  This  is  prepared  by  passing  vapor  of  sulphur  over  heated 
charcoal.  It  is  a  highly  refractive,  colorless,  volatile,  inflammable 
liquid,  neutral  in  reaction,  with  a  peculiar  odor.  It  boils  at  46° 
C.  (115°  F.).  It  is  not  miscible  with  water,  but  freely  dissolves  in 
alcohol,  ether,  and  chloroform.  It  is  a  valuable  solvent  for  iodin, 
phosphorus,  sulphur,  etc. 

Toxicology. — Owing  to  its  employment  in  the  manufacture  of 
vulcanized  rubber,  cases  of  chronic  poisoning  from  inhaling  the 
vapor  are  not  rare.  Workmen  exposed  to  it  in  imperfectly  ven- 
tilated factories  experience  at  first  a  form  of  excited  intoxication 
characterized  by  vivacious  talking,  singing,  immoderate  laughter, 
causeless  weeping,  and  delirium.  They  also  complain  of  head- 
ache, vertigo,  and  muscular  cramps.  If  the  person  does  not 
change  his  occupation  the  second  stage  appears,  in  which  there 
is  headache,  drowsiness,  melancholy,  weakness,  and  loss  of  feeling 
in  the  extremities,  ending  in  paralysis. 
13 


194 


NON-METALS 


THE  CYANOGEN   GROUP 


One  of  the  simplest  compounds  of  carbon  is  the  gas  cyanogen, 
(CN)2,  formed  when  carbon  and  nitrogen  unite  in  the  heat  of  the 
electric  arc.  All  of  its  derivatives  contain  the  group  CN,  just  as 
the  chlorids,  hypochlorites,  etc.,  contain  Cl. 

Many  of  its  compounds  have  properties  resembling  those  of 
the  chlorin  family,  though  they  contain  this  univalent  group  of 
atoms,  CN,  in  place  of  the  single  atom,  Cl.  Sometimes  it  is  writ- 
ten Cy,  to  indicate  that  the  group  CN  acts  like  a  single  element, 
just  as  NH4  behaves  like  the  single  atom  of  an  alkaline  metal. 

The  term  compound  radical  is  applied  to  a  group  playing  the 
part  of  an  atom.  The  relation  between  HCN  and  HC1  is  shown 
by  the  following  examples,  in  which  H  or  a  metal  is  the  electro- 
positive simple  radical  and  CN  the  electro-negative  compound  radical. 

HC1,    KC1,    AgCl,    HgCl2,    HOC1. 
HCN,  KCN,  AgCN,  Hg(CN)2,  HOCN. 

Preparation. — Cyanogen  is  prepared  by  heating  mercuric 
cyanid  to  a  red  heat  in  a  hard  glass  reduction  tube,  connected  by 
a  perforated  cork  and  delivery  tube  with  a  trough  of  mercury: 

Hg(CN)2  =  Hg+C2N2. 

Mercury  is  deposited  upon  the  cool  portions  of  the  tube. 

Properties. — The  free  gas  is  colorless,  condensing  to  a  liquid 
under  a  pressure  of  four  atmospheres;  it  has  a  characteristic  odor, 
is  an  active  poison,  and  burns  with  a  purple  flame  into  carbon 
dioxid  and  nitrogen.  It  is  soluble  in  water  and  alcohol,  but  its 
aqueous  solution  is  unstable,  depositing  a  brownish  precipitate. 

Hydrocyanic  Acid  (HCN)  (Prussic  Acid).—  This  compound 
is  sometimes  called  absolute,  pure,  or  anhydrous,  to  distinguish  it 
from  the  official  form,  acidum  hydrocyanicum  dilutum,  which  con- 
tains not  less  than  2  per  cent,  of  the  anhydrous,  according  to  the 
pharmacopeias  of  U.  S.,  Great  Britain,  Prussia,  Switzerland,  and 
Norway.  The  French  official  article  contains  10  per  cent.,  which 
is  the  average  strength  of  Scheele's  acid.  They  are  all  so  unstable 
that  in  any  but  fresh  specimens  the  strength  is  uncertain.  The 
following  parts  of  plants  can  be  made  to  yield  HCN  by  appropriate 
treatment:  wild-cherry  bark;  flowers  and  leaves  of  the  laurel  and 
the  peach;  kernels  of  peach,  plum,  apple,  cherry,  and  apricot;  the 
bark,  leaves,  flowers,  and  fruit  of  the  wild  service  tree  (Prunus 
padus}-,  the  leaves  and  flowers  of  the  shrubby  spiraea.  These  and 
other  plants  contain  amygdalin,  a  glucosid  found  abundantly  in 


THE    CYANOGEN    GROUP  195 

Amygdala  amara,  the  bitter  almond.  When  the  vegetable  tissue 
is  bruised  or  chewed,  amygdalin  is  brought  into  contact  with  emul- 
sin,  a  ferment  which  in  the  presence  of  water  breaks  up  the  amyg- 
dalin into  hydrocyanic  acid  and  other  compounds: 

C22H27NOU     +     2H20     -     HCN     +     2C6H12O6     +     C7H6O 

Amygdalin.  Hydrocyanic  Glucose.  Oil  of  bitter 

acid.  almonds. 

According  to  Liebig  and  Wohler,  17  gm.  of  amygdalin  yield 
i  of  hydrocyanic  acid  and  8  of  oil  of  bitter  almonds. 

Oleum  amygdala?  amarce  contains  2  to  4  per  cent,  of  hydro- 
cyanic acid. 

Preparation. — Prussic  acid  can  be  prepared  by  the  action  of 
hydrochloric  acid  on  silver  cyanid: 

AgCN          +          HC1  AgCl          +          HCN 

Silver  cyanid.  Hydrocyanic  acid. 

The  silver  chlorid  is  precipitated,  and  the  acid  collected  in  the 
filtrate.  Usually  it  is  made  by  distilling  potassium  ferrocyanid  or 
cyanid  with  sulphuric  acid,  just  as  hydrochloric  acid  is  made  by 
the  action  of  sulphuric  acid  on  sodium  chlorid. 

KCN         +         H2SO4  HCN         +        KHSO4. 

Potassium  cyanid. 

The  dilute  acid  (2  per  cent.)  is  the  only  form  used  in  medicine. 
Its  dose  is  2  to  5  Til  (0.12-0.33  gm.),  repeated  at  short  intervals. 
It  is  incompatible  with  salts  of  copper,  iron,  and  silver.  When  it 
turns  brown  it  is  unfit  for  use. 

Properties. — Absolute  or  anhydrous  prussic  acid  is  a  colorless 
volatile  liquid  with  an  odor  like  oil  of  bitter  almonds.  It  reddens 
litmus  feebly,  dissolves  freely  in  water,  but  the  solution  rapidly 
separates  a  brown  substance  and  changes  to  ammonium  formate: 

HNC          +        2H2O  NH4H.CO2 

Ammonium  formate. 

It  is  a  poison  so  powerful  and  unstable  that  it  is  not  kept  in 
the  drug-stores  in  its  anhydrous  form. 

Toxicology. — The  least  quantity  that  has  destroyed  life  is 
i  fl.  dr.  of  the  official  dilute  acid  or  A  gr.  of  the  anhydrous  acid. 
The  inhalation  of  the  vapor  has  produced  death.  Recovery  has 
occurred  after  taking  i  fl.  dr.  of  Scheele's  acid,  and  in  another  case 
after  2  fl.  dr.  of  the  official  acid,  which,  if  not  deteriorated,  should 
have  been  equal  to  2.4  gr.  of  anhydrous  acid. 


!g6  NON-METALS 

Symptoms. — Prussic  acid  is  a  retarding  catalyzer — i.  e.,  by  its 
presence  prevents  oxidation  and  other  vital  processes  important 
to  the  life  of  the  organism.  It  depresses  the  nutrition  of  proto- 
plasms in  plants  and  animals.  Applied  externally,  care  must  be 
exercised  lest  the  poison  enter  by  open  cuts.  The  anhydrous 
acid  has  been  used  as  a  local  application  for  allaying  oversensi- 
tive conditions  of  the  cutaneous  nerves.  Instant  death  may  follow 
large  doses  by  the  mouth  or  the  inhalation  of  vapor  of  the  strong 
acid. 

If  death  is  not  instantaneous,  then  in  a  few  seconds  there  will 
be  giddiness,  relaxed  muscles,  causing  a  fall  to  the  earth,  convul- 
sions, stertorous  breathing,  slowing  of  the  pulse,  closed  jaws,  clammy 
skin,  odor  of  bruised  peach-kernels  on  the  breath,  dilated  pupils, 
asphyxia,  stupor,  ending  in  coma.  In  some  cases  the  resemblance 
to  apoplexy  is  so  marked  as  to  cause  mistake  in  diagnosis.  Insensi- 
bility is  not  always  immediate,  though  death  is  usually  preceded 
by  convulsions  and  coma.  Death  is  due  to  arrested  respiration. 

Fatal  Period. — In  most  cases  ten  minutes  elapse  before  death. 
Consciousness  may  be  lost  in  a  few  seconds,  the  suicide  falling 
dead  in  two  minutes. 

It  is  possible  that  life  may  be  prolonged  for  three  hours  and  a 
half,  but  in  most  cases  if  the  patient  live  an  hour  he  will  recover. 

Treatment. — If  strong  prussic  acid  has  been  taken  there  is  rarely 
time  for  treatment.  After  potassium  cyanid  or  the  dilute  acid 
there  may  be  opportunity  for  the  following  procedure: 

Give  prompt  emetics,  such  as  mustard  and  water,  aided  by 
tickling  the  throat. 

By  the  flexible  tube,  siphon  out  the  stomach  with  Robert's 
antidote — dilute  solution  of  hydrogen  peroxid,  which  slowly  con- 
verts HCN  into  relatively  harmless  oxamid: 

2HCN     +      H202      =      C202N2H4 

Hydrogen  peroxid.  Oxamid. 

If  potassium  cyanid  was  the  form  of  poison,  add  vinegar  to  the 
hydrogen  peroxid.  Should  death  be  delayed  there  may  be  time 
for  the  antidote  of  potassium  carbonate,  gr.  xx,  dissolved  in  water, 
f^j,  followed  with  a  mixture  of  ferrous  sulphate,  gr.  x,  and  mag- 
nesia, gr.  xxx,  in  water,  f^j.  The  poisonous  anion  cyanidion, 
(CN)',  is  changed  to  ferrocyanidion,  Fe(CN)6"",  which  is  not 
poisonous  in  the  presence  of  an  alkali. 

In  mining  and  photographic  laboratories  the  materials  for  this 
antidote  should  be  kept  made  up  in  packages  and  the  stomach 
tube  be  always  at  hand  for  use  without  delay. 

Cold   affusions   over  the    face   and    chest    and    inhalations    of 


THE    CYANOGEN    GROUP  197 

ammonia  may  be  assisted  by  brandy  subcutaneously  administered, 
frictions  to  the  extremities,  and  artificial  respiration. 

Atropin,  ^  gr.,  may  be  given  hypodermically  as  a  stimulant 
to  heart  and  respiration. 

Postmortem  Appearances.  —  The  odor  of  bruised  peach-kernels 
may  be  noticed  in  the  room  or  on  the  body.  There  are  no  char- 
acteristic lesions,  but  most  frequently  there  is  engorgement  of  the 
venous  system,  the  arteries  being  empty.  The  postmortem  stains 
are  bright  pink,  due  to  the  cyanohematin  of  the  blood  and  to  the 
fact  that  the  tissues  cannot  take  up  the  oxygen  of  the  blood, 
leaving  it  red  even  in  the  veins. 

Tests.  —  Silver  nitrate  produces  a  white  precipitate,  soluble  in 
boiling,  strong,  nitric  acid: 


HCN  +  AgN03  =  HN03  +  AgCN. 

This  white  silver  cyanid  is  distinguished  from  the  chlorid  oy 
being  only  sparingly  soluble  in  ammonia,  by  its  not  turning  dark 
on  exposure  to  light,  and  by  giving  off  cyanogen  gas  when  heated, 
the  cyanogen  burning  with  a  purple  flame.  Under  a  lens  the 
cyanid  may  appear  as  prismatic  needles,  while  the  chlorid  is 
amorphous. 

The  most  delicate  test  is  this  one  used  on  HCN  in  the  state  of 
vapor.  The  suspected  matters  are  put  in  a  beaker  which  is  im- 
mersed in  a  basin  of  warm  water.  The  mouth  of  the  jar  is  cov- 
ered with  a  watch  crystal,  which  has  on  its  concave  under  side 
a  drop  of  weak  solution  of  silver  nitrate.  Hydrocyanic-acid  vapor 
causes  a  white  film  over  the  drop,  which,  if  slowly  formed,  will  be 
seen  by  the  microscope  to  consist  of  delicate  crystalline  prisms. 
If  putrefaction  has  set  in,  the  test  cannot  be  used,  as  the  black 
silver  sulphid  masks  the  white  cyanid. 

Prussian-blue  Test.  —  On  the  addition  of  potassium  hydrate, 
followed  by  fresh  ferrous  sulphate  and  ferric  sulphate,  a  greenish- 
blue  precipitate  forms,  which  is  turned  to  a  clear  Prussian  blue  by 
the  addition  of  hydrochloric  acid. 

iSHCN    +    iSKHO    +    5FeSO4    +    Fe2(SO4)3   +    H2SO4   = 

Ferrous  sulphate.        Ferric  sulphate. 

9K2S04    +    Fe4(Fe(CN)fl),    +    i8H2O    +    H2. 

Ferric  ferrocyanid. 

Ammonium-sulphid  test  may  be  used  upon  fluids  in  a  test-tube, 
but  gives  best  results  with  the  vapor  of  HCN,  even  after  putre- 
faction has  begun.  The  stomach  contents  or  other  suspected 
matter  are  put  in  a  jar  which  is  immersed  in  warm  water,  and  the 
mouth  closed  with  a  glass  plate  carrying  a  drop  of  ammonium 


198  NON-METALS 

sulphid.  A  white  ammonium  sulphocyanate  soon  appears  in  this 
drop  on  the  under  side.  This  drop  is  then  evaporated  almost  to 
dryness  and  touched  with  a  drop  of  ferric  chlorid,  when  it  de- 
velops a  blood-red  color,  which  is  discharged  after  treating  with 
mercuric  chlorid: 

HCN     +      NH4HS      =      2H      +      NH4SCN 

Ammonium  sulphid.  Ammonium  sulphocyanate. 

3NH4SCN     +     FeCl3     =     3NH4C1     +     Fe(SCN)3 

Ferric  chlorid.       Ammonium  chlorid.       Iron  sulphocyanate. 

Detection. — If  death  has  been  recent,  the  odor  of  peach- 
kernels  may  be  perceived.  The  stomach,  its  contents,  and  other 
tissues  should  be  distilled  at  a  low  temperature  without  acidu- 
lating, as  acids  may  form  a  cyanid  by  decomposing  the  normal 
potassium  sulphocyanate  of  the  saliva. 

Instead  of  acidulating  the  suspected  matter  before  distillation, 
Jacquemin's  process  is  to  mix  it  with  a  concentrated  solution  of 
sodium  bicarbonate,  which  evolves  CO2,  a  gas  that  promotes  the 
escape  of  HCN  and  liberates  HCN  if  potassium  cyanid  be  pres- 
ent, but  does  not  decompose  potassium  sulphocyanate  nor  potas- 
sium ferrocyanid  nor  other  non-poisonous  cyanids. 

Any  of  the  above  tests  may  be  applied  to  the  vapor,  or  the 
distillate  in  the  receiver  may  be  treated  with  potassium  hydrate 
and  tested  for  potassium  cyanid  by  silver  nitrate.  The  resulting 
silver  cyanid  is  washed,  dried,  and  weighed.  For  every  100  parts 
of  AgCN  we  may  calculate  20.15  parts  of  anhydrous  HCN. 

Potassium  Cyanid  (KCN).—  This  compound  figures  quite 
frequently  .as  a  poison,  because  of  its  extensive  use  in  the  arts  of 
photography  and  electroplating,  and  in  the  extraction  of  gold 
from  its  ores  by  the  cyanid  process. 

Properties. — It  occurs  in  opaque,  white,  strongly  alkaline,  del- 
iquescent masses,  which  have  the  taste  of  bitter  almonds,  and  in 
contact  with  the  air  are  decomposed  by  CO2  with  the  slow  forma- 
tion of  hydrocyanic  acid,  recognized  by  the  odor. 

As  hydrocyanic  acid  is  a  weak  acid,  its  salt  is  hydrolyzed  by 
the  water,  forming  hydroxidion,  which  is  alkaline,  and  hydrogen 
cyanid,  which  is  scarcely  dissociable,  and  hence  is  given  off  as 
molecules  with  the  characteristic  odor.  This  is  in  accordance 
with  the  equation: 

KCN       +       H2O       =       K',(OH)'       +       HCN. 

It  is  soluble  in  two  parts  of  water,  and  is  sometimes  used  in 
medicine  as  a  sedative  in  doses  of  217  to  ^  gr.  Its  incompatibles  are 


THE    CYANOGEN    GROUP  199 

acids;  iodin;  salts  of  lead,  mercury,  and  silver;  chlorates;  nitrates; 
permanganates;  alkaloids;  chloral  hydrate. 

Toxicology. — Symptoms. — Its  physiologic  effects  are  like  those 
of  hydrocyanic  acid.  The  convulsive  and  narcotic  symptoms  are 
often  preceded  by  those  of  gastric  irritation,  such  as  pain  and 
vomiting.  The  onset  of  symptoms  is  slower  than  by  the  acid, 
thus  giving  more  time  for  treatment. 

The  treatment  is  practically  the  same  as  that  given  for  the  acid, 
p.  196. 

Postmortem  Appearances. — There  is  usually  marked  congestion 
of  the  stomach,  due  to  the  strongly  alkaline  salt.  A  bright  red 
hue  is  observable  in  the  throat,  esophagus,  and  stomach,  due  to 
the  formation  of  cyanohematin  by  the  penetration  of  the  salt  to 
the  blood  in  the  tissues. 

Tests. — When  treated  with  dilute  acids  potassium  cyanid  is 
quickly  decomposed,  and  to  the  vapor  the  various  tests  for  hydro- 
cyanic acid  may  be  applied.  Silver  nitrate  reacts  directly,  precipi- 
tating white  silver  cyanid;  and  the  potassium  is  detected  by  plat- 
inum chlorids.  In  making  the  Prussian-blue  test  the  potassium 
hydrate  must  be  omitted,  unless  followed  by  excess  of  HC1. 

Other  Cyanids.— The  soluble  metallic  cyanids  and  methyl 
cyanid  are  all  poisonous,  as  they  dissociate  the  active  anion  (CN)'. 
If  the  cation  be  poisonous  also,  as  in  mercury  cyanid,  Hg',  (CN)2', 
the  symptoms  will  be  those  of  an  irritant  mercurial  salt  in  addition 
to  those  of  potassium  cyanid. 

Poisonous,  also,  are  the  chlorid  and  iodid  of  cyanogen.  In 
neutral  or  alkaline  menstrua  the  double  cyanids,  not  having  as 
anion,  cyanidion,  (CN),  but  ferrocyanidion,  Fe(CN)6////,  are  con- 
sidered relatively  harmless.  It  must  not  be  forgotten  that  in  the 
presence  of  acids  the  iron  of  Fe(CN)6""  may  be  taken  up,  and  the 
(CN)  group  be  freed  to  do  its  deadly  work. 

In  cyanic  acid  and  its  salts,  the  cyanates,  the  anion  is  not  (CN)', 
but  (OCN)',  which  is  not  poisonous.  The  sulphocyanates  are  not 
seriously  injurious,  as  they  have  the  anion  (SCN)'. 

Cyanic  acid,  H .  OCN,  is  a  strongly  acid,  unstable  liquid, 
forming  cyanates.  In  water  it  quickly  changes  to  acid  ammonium 
carbonate : 

HOCN         +         2H20  (NH4)HC03. 

Potassium  cyanate,  KOCN,  is  formed  when  potassium  cyanid 
slowly  oxidizes  in  the  air,  though  it  is  usually  prepared  by  heating 
KCN  with  a  reducible  metallic  oxid  and  then  extracting  the  prod- 
uct with  dilute  alcohol: 

KCN        +        PbO        =        KOCN        +        Pb. 


200  NON-METALS 

It  is  a  colorless  crystal  and  readily  soluble.  When  its  solution  is 
mixed  with  ammonium  sulphate,  ammonium  cyanate  is  formed: 

2KCNO     +     (NH4)2S04     =     2(NH4).CNO     +     K2SO4. 

Ammonium  cyanate. 

If  the  resulting  solution  be  evaporated  on  a  water-bath,  the 
ammonium  cyanate  is  transformed  into  urea.  It  was  in  this  way 
that  Wohler  first  produced  urea  by  artificial  synthesis.  There  is 
no  addition  or  subtraction  of  atoms,  as  the  two  substances  have 
the  same  molecular  formula.  The  change  is  termed  intramolecular 
and  may  be  expressed  by  the  constitutional  formulas  given  below: 

NH4.O.CN  CO(NH2)2 

Ammonium  cyanate.  Urea  or  carbonyl  diamid. 

It  is  believed  that  there  is  a  migration  of  atoms  to  differently 
arranged  groups.  The  two  bodies  are  said  to  be  isomeric — i.  e., 
although  they  have  the  same  composition  their  properties  differ 
because  of  a  difference  of  arrangement  in  the  atoms. 

OXALIC  ACID   (Acid  of  Sugar) 
Formula,  C2H2O4  +  2H2O.     Molecular  weight,  125.7. 

Oxalic  acid  and  its  salts  are  widely  present  in  nature,  being  found 
in  various  plants,  such  as  rhubarb  (used  for  pies),  nightshade,  dock, 
sorrel  (oxalis)  (used  for  greens),  and  in  animals  also,  occurring  not 
infrequently  as  a  constituent  of  the  human  urine.  In  the  latter 
it  is  incidental  to  the  gouty  condition  and  some  forms  of  dyspepsia, 
occurring  as  calcium  oxalate  in  the  form  of  a  whitish  deposit  made 
up  of  microscopic  crystals,  octahedral  or  dumb-bell  shaped,  and 
insoluble  in  warm  water  and  in  acetic  acid  (p.  591). 

Preparation. — As  a  sodium  salt  it  may  be  prepared  by  passing 
carbon  dioxid  over  sodium  heated  carefully: 

Na2         +          2CO2  Na2C2O4 

Sodium.  Carbon  dioxid.  Sodium  oxalate. 

It  can  be  prepared  from  sugar  by  oxidation  with  nitric  acid,  and, 
therefore,  is  sometimes  known  in  the  arts  as  acid  of  sugar. 

C12H220U       +       902       =       6C2H204       +       5H20. 

Sugar.  Oxalic  acid. 

Its  bleaching  properties  and  solvent  powers  for  metallic  oxids 
make  it  useful  to  dyers  and  workers  in  leather,  makers  of  straw 
hats  and  bonnets,  and  workers  in  marble  and  in  brass.  About 
the  home  it  is  used  to  remove  ink-stains  from  linen.  Druggists 
dispense  it  at  a  low  price,  and  consequently  the  would-be  suicide 


OXALIC    ACID  201 

not  infrequently  resorts  to  it.  Its  resemblance  to  Epsom  salts 
leads  to  accidental  poisoning,  but  the  very  sour  taste  is  likely  to 
betray  the  homicide,  who  rarely  resorts  to  it  except  when  it  can 
be  masked  by  some  other  sour  beverage. 

Properties. — The  crystals  of  oxalic  acid  are  colorless,  four- 
sided,  prismatic,  not  deliquescent,  and  so  closely  resemble  in  ap- 
pearance those  of  magnesium  sulphate  and  zinc  sulphate  that  it  is 
often  confounded  with  them.  These  crystals  are  very  acid,  soluble 
in  about  10  parts  of  cold  water  and  in  2j  of  cold  alcohol,  but  very 
sparingly  in  ether.  Heated  on  porcelain  or  platinum,  they  sublime 
without  residue.  They  contain  two  parts  water  of  crystallization. 

It  can  be  distinguished  from  the  substances  for  which  it  is 
sometimes  mistaken  by  the  following  ready  tests,  applicable  in 
the  household: 

Oxalic  acid.                       Magnesium  sulphate.  Zinc  sulphate. 

Taste   ......  Sour.  Bitter,  nauseous.  Bitter,  metallic. 

Reaction     ....  Very  acid.  Neutral.  Slightly  acid. 

Heated Sublimes.  Fixed.  Fixed. 

Sodium  carbonate  .  No  precipitate,  No  effervescence,  but  a     No  effervescence,  but  a 

but  effervescence,      white  precipitate.  white  precipitate. 

Iron.,  ink     ....  Bleaches.  No  effect.  No  effect. 

As  it  is  a  dibasic  acid  it  makes  two  salts  with  univalent  metals. 
With  potassium  it  forms  KHC2O4  and  K2C2O4. 

Potassium  Binoxalate  (KHC2O4,H2O)  (Acid  Oxalate}.— 
This  salt  is  usually  dispensed  by  druggists  to  remove  rust  and 
ink-stains  from  linen,  to  bleach  straw,  and  to  polish  metals,  under 
the  very  deceptive  name  of  "essential  salts  of  lemon"  and  "salts 
of  sorrel,"  and  sometimes  without  even  the  "grim  heraldry  of 
death"  usually  blazoned  on  labels  for  poisonous  substances.  It 
is  sometimes  dispensed  as  a  white  powder,  although  it  crystallizes 
in  colorless  rhombic  prisms,  having  i  part  of  water  of  crystallization. 
It  has  a  decidedly  acid  reaction  and  sour  taste,  and  is  soluble  in  40 
parts  of  water.  It  is  likely  to  be  mistaken  for  cream  of  tartar, 
which  is  also  a  sour  white  solid.  Almost  equal  to  oxalic  acid  in 
the  violence  of  its  poisonous  action,  its  symptoms,  postmortem 
appearance,  antidotes,  and  detection  are  practically  the  same. 

The  same  may  be  said  in  lower  degree  to  be  true  of  the  neutral 
potassium  oxalate  (K2C2O4),  which  is  white,  crystalline,  soluble 
in  water  and  neutral  in  reaction.  Not  being  used  in  the  household 
it  does  not  figure  in  toxicology,  though  when  absorbed  it  is  a  violent 
neurotic  poison. 

Toxicology. — Symptoms. — What  is  said  of  the  toxic  effects  of 
oxalic  acid  is  applicable  also  to  potassium  binoxalate.  While  the 
symptoms  vary  considerably  in  different  cases,  they  can  be  con- 
veniently classified  as,  first,  those  due  to  the  local  erosive  action  on 


202  NON-METALS 

the  mucous  surfaces,  and,  second,  those  arising  from  the  remote 
impression  upon  the  nervous  system — convulsive  and  narcotic. 
The  symptoms  produced  by  the  local  action  of  a  large  amount 
of  a  strong  solution  are  very  sour  taste,  thirst,  pain,  and  burning 
in  mouth,  throat,  and  stomach,  difficult  swallowing,  vomiting  of 
black  or  bloody  substances,  collapse.  Occasionally  pain  is  absent. 
Sometimes  death  may  occur  without  vomiting. 

"If,"  says  Christison,  "a  person  immediately  after  swallowing 
a  solution  of  a  crystalline  salt  which  tasted  purely  and  strongly 
acid  is  attacked  with  burning  in  the  throat,  then  with  burning  in 
the  stomach,  vomiting,  particularly  of  bloody  matter,  imperceptible 
pulse  and  excessive  languor,  and  dies  in  half  an  hour,  or  still  more 
in  twenty,  fifteen,  or  ten  minutes,  I  do  not  know  any  fallacy  which 
can  interfere  with  the  conclusion  that  oxalic  acid  was  the  cause 
of  death.  No  parallel  disease  begins  so  abruptly  and  terminates 
so  soon,  and  no  other  crystalline  poison  has  the  same  effect." 

A  case  of  oxalic-acid  poisoning  occurred  in  a  boy  aged  fifteen 
years.  Twelve  minutes  after  the  poison  had  been  swallowed  the 
patient  was  unconscious,  the  skin  pallid  and  clammy,  and  his  ex- 
tremities cold.  The  radial  pulse  could  not  be  felt.  The  pupils 
were  fairly  dilated.  The  jaw  was  fixed  in  tetanic  spasm,  and  froth 
exuded  from  between  the  teeth.  One-tenth  of  a  grain  of  apomor- 
phin  was  injected  hypodermically;  a  stomach  siphon-tube  was 
introduced  after  the  jaws  had  been  forced  apart,  and  i  pint  of 
warm  water  was  placed  in  the  stomach,  but  immediately  expelled. 
Vomiting  continued,  and  consciousness  returned.  The  boy  was 
given  J  oz.  of  powdered  chalk,  suspended  in  water,  and  this  also 
was  shortly  ejected.  Recovery  proceeded  under  stimulation.  The 
quantity  of  poison  taken  was  upward  of  2^  drams. 

If,  owing  to  the  smallness  of  the  dose,  death  is  not  prompt, 
absorption  of  the  poison  ensues,  and  then  the  remote  or  neurotic 
symptoms  appear.  These  are  headache,  cramps,  convulsions, 
delirium,  and  coma.  If  the  patient  survive,  there  may  be  numb- 
ness and  tingling,  with  loss  of  voice,  lasting  for  weeks.  When  a 
small  dose  has  been  taken  in  dilute  solution,  the  symptoms  have 
not  come  on  for  hours,  and  then  the  nervous  phenomena  are 
more  prominent. 

Fatal  Dose. — The  least  weight  of  the  acid  recorded  as  having 
fatal  consequences  is  i  dram  (3.88  grams).  Statistics  show  that 
the  dose  most  likely  to  prove  fatal  is  from  J  to  i  oz.  Early  vom- 
iting and  a  measure  of  relief  are  caused  by  excessive  doses.  More 
than  i  oz.  (14.2  gm.),  if  retained,  usually  causes  death,  although 
recovery  has  occurred  after  a  dose  of  2  oz. 

If  efficient  antidotes  are  instantly  given  there  may  be  recovery 
from  much  larger  doses,  although  the  majority  of  cases  prove  fatal. 


OXALIC    ACID  203 

Fatal  Period. — In  i  case  death,  supposed  to  be  due  to  gas- 
tric hemorrhage,  occurred  without  pain  in  three  minutes.  In  other 
cases  surviving  the  acute  action  on  the  alimentary  tract  death  has 
occurred  from  coma  after  several  days,  i  living  until  the  twenty- 
third  day. 

Treatment. — The  chemical  antidotes  are  finely  divided  chalk  or 
calcined  magnesia  or  its  carbonate,  suspended  in  a  large  quantity 
of  water,  and  followed  by  free  drafts  of  warm  water  to  facilitate 
vomiting.  As  the  toxic  action  is  prompt,  the  antidote  must  be 
given  at  once.  With  a  shovel  or  a  kitchen  knife  the  wall-plaster 
can  be  scraped  off  and  used  as  an  impure  calcium  carbonate. 

Oxalic  acid  is  chemically  neutralized  by  the  alkalies  as  well  as 
by  the  alkaline  earths  (lime  and  magnesia),  but  the  alkaline 
oxalates,  being  soluble  and  poisonous,  are  inadmissible,  while  the 
oxalates  of  calcium  and  magnesium  are  insoluble  and  innocuous. 
Emetics  may  be  necessary  (such  as  5  drops  of  a  2  per  cent,  solu- 
tion of  apomorphin  hydrochlorate).  If  the  stomach-pump  have  a 
hard  tube  it  is  likely  to  injure  the  eroded  lining  of  the  gullet  and 
stomach. 

Postmortem  Appearances. — Colored  stains  upon  the  lips  and 
face  are  absent,  but  the  lips,  tongue,  throat,  and  gullet  are  usually 
white,  and  the  lining  membrane  is  loose,  eroded  in  patches,  and 
contracted  into  folds.  Sometimes  the  stomach  is  black  from  ex- 
tensive venous  engorgement  and  contains  blood  or  a  brownish, 
grumous  material;  sometimes  the  membrane  is  pale  and  smooth, 
or  detached  in  shreds;  sometimes  red,  with  the  black  veins  strongly 
marked  and  corrugated.  While  deep  erosions  are  not  uncommon, 
it  is  rare  to  have  complete  solution  of  the  walls  of  the  stomach, 
so  as  to  cause  the  symptoms  of  perforation  during  life,  Both 
peritonitis  and  pleuritis  have  been  found  as  complications,  and 
perforations  of  the  stomach  also,  but  these  last  in  some  cases 
have  been  supposed  to  be  due  to  changes  after  death.  The  kid- 
neys are  congested  and  loaded  with  oxalates. 

Tests. — A  solution  of  oxalic  acid  or  of  potassium  binoxalate 
reddens  litmus-paper. 

Calcium  Test. — Either  of  them  yields,  with  excess  of  calcium 
hydroxid,  acetate,  or  sulphate,  a  white  precipitate  of  calcium 
oxalate,  insoluble  in  ammonia  or  acetic  acid,  but  soluble  in  strong 
hydrochloric  or  nitric  acid. 

Silver  Nitrate  Test. — Either  of  them  gives  with  silver  nitrate 
a  copious  white  precipitate  of  silver  oxalate,  soluble  in  ammonia 
and  in  nitric  acid,  while  silver  chlorid  would  be  insoluble  in  the 
nitric  acid.  The  silver  oxalate,  dried  and  heated  on  platinum, 
disperses  with  a  slight  explosion  and  a  white  smoke. 

Lead  Acetate   Test. — With  lead  acetate  a  white  precipitate  of 


204  NON-METALS 

lead  oxalate  is  formed  which  is  soluble  in  nitric  acid,  but  insoluble 
in  acetic  acid. 

Potassium  Permanganate  Test. — Mixed  with  potassium  per- 
manganate and  dilute  sulphuric  acid  the  oxalic  acid  is  oxidized 
(H2C2O4+O  =  2CO2  +  H2O),  and  the  permanganate,  slowly  losing 
its  color,  is  converted  into  manganese  sulphate. 

Sublimation  Test. — Heated  on  platinum  foil,  the  acid  crystals 
slowly  sublime  at  as  low  a  temperature  as  100°  C.  (212°  F.),  and 
they  are  entirely  and  promptly  dissipated  at  160°  C.  (302°  F.). 
At  this  temperature  a  large  part  is  decomposed,  first  into  formic 
acid  and  carbon  dioxid.  Thus: 

H2C204  H2C02        +         C02. 

Formic  acid. 

The  rising  temperature  then  decomposes  the  formic  acid  into 
carbon  monoxid  and  water.  Thus: 

H2C02  CO          +          H20. 

The  potassium  oxalate  does  not  sublime,  but  changes  to  potas- 
sium carbonate,  which  effervesces  when  touched  with  an  acid,  and 
turns  red  litmus-paper  blue. 

K2C204  K2C03         +         CO 

Potassium  oxalate.  Potassium  carbonate.  Carbon  monoxid. 

Detection. — The  symptoms  of  corrosive  poisoning  from  an  acid 
liquid  which  has  left  no  colored  spots  upon  the  skin  would  be 
significant.  A  strong  solution  makes  on  black  cloth  a  dark- 
brown,  uncorroded  spot,  which  gives  the  oxalic  acid  reactions. 
The  vomited  matters  should  be  searched  for  the  leaves  of  sorrel 
or  green  material  of  the  rhubarb  pie;  not  that  these  are  ever  fatal, 
but  so  as  to  exclude  the  possibility  of  a  complication  in  the  anal- 
ysis. In  the  vomited  matters  and  gastric  contents  the  acid  will 
be  partly  free,  partly  combined  as  soluble  oxalate,  and  partly 
combined  as  the  insoluble  calcium  or  magnesium  oxalates.  If  it 
should  be  mostly  free,  the  following  method  will  serve: 

1.  Having  made  an  extract  with  hot  dilute  hydrochloric  acid 
and  filtered  it,  add  lead  acetate,  which  will  throw  down  the  lead 
oxalate  along  with  various  other  lead  compounds.     This  deposit 
should  be  suspended  in  water  and  hydrogen  sulphid  passed  through 
it  for  two  hours.     The  oxalic  acid  is  set  free  in  solution,  the  black 
lead  sulphid  being  thrown  down.     After  separation  by  a  filter  the 
filtrate  should  be  tested  with  calcium  acetate. 

2.  If  the  oxalic  acid  is  in  the  combined  state,  the  following 
is  the  better  method:   Digest  the  suspected  matters  with  warm 


SILICON  205 

dilute  hydrochloric  acid  until  the  mixture  is  quite  fluid,  filter,  and 
to  the  filtrate  add  ammonium  hydroxid  until  an  alkaline  reaction 
is  reached.  After  standing  the  liquid  is  decanted  and  the  deposit 
collected  on  a  filter.  This  deposit  is  calcium  oxalate.  The  fil- 
trate mixed  with  the  decanted  fluid  is  treated  with  excess  of  calcium 
acetate  and  the  precipitate  separated  on  a  filter.  This  second 
deposit  represents  the  free  acid  in  the  original  material.  To 
determine  the  nature  and  amount  of  the  first  deposit,  it  should  be 
washed  with  acetic  acid  on  the  filter  and  afterward  put  into  a 
beaker  and  dissolved  by  cautiously  adding  strong  hydrochloric 
acid  and  gently  heating.  Excess  of  ammonia  will  precipitate  it 
completely  if  sufficient  time  is  allowed.  After  decanting  the  clear 
fluid  the  deposit  is  washed  by  decantation,  put  into  a  tared  dish, 
dried  in  a  water-bath,  and  weighed.  If  this  deposit  is  calcium 
oxalate,  it  will  be  white,  and  when  a  portion  is  heated  on  platinum, 
leave  a  gray  ash  of  calcium  carbonate.  Another  portion  warmed 
in  a  test-tube  with  strong  sulphuric  acid  evolves  carbon  dioxid  gas, 
which  can  be  identified  by  conducting  it  through  a  delivery  tube 
into  baryta  water.  A  third  portion,  suspended  in  water  slightly 
acidulated  with  sulphuric  acid,  will  discharge  the  purple  color  of 
potassium  permanganate.  This  test  can  be  applied  by  standard 
volumetric  solutions  and  an  estimate  of  quantity  obtained. 

If  the  poison  has  been  taken  as  neutral  sodium  or  potassium 
oxalate,  the  local  symptoms  and  pathologic  changes  may  not  be 
at  all  characteristic.  The  effects  come  on  after  absorption  and 
are  mainly  systemic.  To  make  a  complete  examination  the  poison 
must  be  looked  for  outside  the  alimentary  canal,  by  separating  it 
from  the  urine  and  the  finely  divided  tissue  of  the  kidney.  The 
method  would  be  the  same  as  that  for  vomited  matters  containing 
the  combined  acid. 

SILICON   (Silex,  a  flint) 

Symbol,  Si.     Atomic  weight,  28. 

Properties. — Silicon  is  a  tetrad  element  like  carbon,  never 
found  native,  but  combined  with  oxygen  as  silica,  SiO2.  Silica 
exists  nearly  pure  in  rock  crystal  or  quartz,  in  sand,  flint,  and 
many  minerals,  and  is  also  found  combined  with  the  metals  as 
silicates.  Silicon,  next  to  oxygen,  is  the  most  abundant  element 
known.  It  resembles  carbon  in  physical  and  chemical  properties. 
Like  carbon  it  has  three  modifications,  viz.: 

Amorphous — a  brown  powder,  only  acted  upon  by  hydrofluoric 
acid,  HF,  which  dissolves  it. 

Gr ap hitoidal— hexagonal  plates  with  metallic  luster. 

Adamantine — in  steel-gray  crystals,  hard  enough  to  scratch 
glass. 


2O6  NON-METALS 

Silicic  Anhydrid,  Silicon  Dioxid  (SiO2)  (SUica).  —  Prop- 
erties.— It  is  a  snow-white,  gritty,  insoluble  powder,  almost 
infusible,  but  soluble  in  hydrofluoric  acid,  HF.  It  is  prepared  by 
heating  metasilicic  acid,  H2SiO3: 

H2SiO3       +       heat       =       H2O       +       SiO2. 

Silica  also  exists,  in  a  crystallized  form,  as  quartz.  Joined  to 
one  or  more  molecules  of  water  silica  forms  a  series  of  acids,  like 
the  phosphoric  acids,  viz.: 

Metasilicic  acid,  SiO2  +  H2O  =  H2SiO3;  and 

Orthosilicic  acid,  SiO2  +  2H2O  =  H4SiO4. 

Metasilicic  acid  (H2SiO3)  is  a  clear  limpid  fluid,  in  a  colloidal 
solution,  with  a  tendency  to  become  gelatinous.  It  is  the  chief 
agent  in  petrifaction.  It  is  prepared  by  acting  upon  potassium 
silicate,  K2SiO3,  with  hydrochloric  acid,  HC1.  Thus: 

K2SiO3      +      2HC1      =       2KC1      +       H2SiO3. 

Orthosilicic  acid  (H4SiO4)  is  a  white  gelatinous  substance  when 
first  precipitated,  and  soluble  until  evaporated  to  dryness.  It  is 
prepared  by  leading  silicon  tetrafluorid,  SiF4,  into  water.  Thus: 

3SiF4       +       4H2O       =       2H2SiF6       +       H4SiO4. 

Orthosilicic  acid  results,  together  with  a  new  acid,  H2SiF6,  to 
which  the  name  of  hydrofluo silicic  acid  is  given. 

Most  of  the  silicates  found  in  nature  are  derived  from  meta- 
silicic acid,  H2SiO3,  to  which  the  normal  or  Orthosilicic  acid  reverts 
when  it  is  set  free,  H4SiO4  losing  H2O,  becoming  H2SiO3. 

Glass. — Silicates  of  the  alkaline  metals  are  soluble,  one  of 
them,  known  as  sodium  water-glass,  was  official  as  liquor  sodii 
silicatis.  This  is  prepared  by  fusing  together  sand  and  dry  sodium 
carbonate:  Na2CO3  +  SiO2  =  Na2SiO3  +  CO2.  Dissolving  in  boil- 
ing water  to  make  a  thick  liquid  it  can  be  used  as  a  cement  or 
artificial  stone.  It  loses  water  rapidly  and  becomes  a  glass.  When 
bandages  and  fracture  dressings  are  covered  with  it  they  soon 
harden  and  make  an  immovable  apparatus.  To  remove  them 
hot  water  must  be  applied.  It  is  no  longer  used  for  bandages. 

Common  glass  is  a  silicate  of  calcium  and  sodium,  lime  being 
introduced  with  sodium  carbonate  to  make  the  glass  insoluble. 

Hard  German,  or  Bohemian  glass,  is  made  with  sand,  lime,  and 
potassium  carbonate.  It  stands  heat  better  than  the  soft  French 
glass,  of  which  chemical  apparatus  is  usually  made. 

Soft  French  glass  is  a  silicate  of  calcium,  sodium,  and  alumin- 
ium. 

English  flint  glass,  used  for  optical  purposes  and  ornamental 
cut  glassware,  has  the  calcium  replaced  with  lead.  It  is  more 
fusible  and  has  a  higher  refracting  power  for  light  rays. 


SILICON  207 

Silicon  hydrid  (SiH4)  is  a  colorless  gas,  taking  fire  spontane- 
ously in  the  air,  forming  water  and  white  cloud  rings  of  silica. 

Silicon  tetrafluorid  (SiF4)  is  a  colorless,  pungent  gas,  fuming 
in  air,  and  is  formed  when  hydrofluoric  acid  comes  in  contact 
with  silica.  It  is  prepared  by  heating  fluorid  of  calcium  with 
sand  or  silica  and  sulphuric  acid: 

2CaF2  +  SiO2  +  2H2SO4  =  2CaSO4  +   2H2O  +  SiF4. 

It  is  decomposed  by  water,  but  may  be  collected  over  mercury, 
or  by  displacement.  A  corresponding  compound  with  bromin  is 
known,  called  Silicon  bromid,  SiBr4. 

Silicon  tetrachlorid  (SiClJ  is  a  colorless,  pungent,  irritating 
liquid,  formed  when  silicon  is  heated  in  chlorin. 

Silicon  resembles  carbon  in  the  composition  of  its  salts.     Thus: 

CO2  H2CO3  CH4  CC14. 

SiO2  H2SiO3  SiH4  SiCl4. 

But  the  two  elements  also  differ  widely  in  some  respects.  While 
both  form  many  compo-unds,  the  carbon  derivatives  have  a  struc- 
ture showing  very  different  relationships  to  the  carbon  from  those 
of  the  silicon  derivatives  to  the  silicon.  Carbon  compounds  appear 
to  be  derived  from  the  hydrocarbons;  silicon  compounds  arise 
from  or  are  related  to  silicon  dioxid. 

Carborundum. — At  the  very  high  temperature  of  3500°  C. 
obtained  in  an  electric  furnace,  the  following  reaction  occurs  in  a 
mixture  of  carbon,  sand,  and  salt: 

SiO2         +         3C  SiC         +          2CO. 

The  greenish-black  mass  SiC  is  called  technically  " carborundum.'' 
It  is  used  as  a  grinding  material,  being  of  sufficient  hardness  to 
replace  the  diamond  in  glass  cutting.  It  resists  the  strongest  acids, 
but  decomposes  by  fusion  with  alkalis. 

"Weathering"  of  Rocks.— It  is  a  remarkable  fact  that 
the  stable  and  insoluble  silicates  in  granite  and  other  primitive 
rocks  when  exposed  to  the  air  break  up  into  loose  soil  and  sol- 
uble carbonates,  by  displacement  of  the  silicic  acid  in  their  con- 
stituents with  the  carbonic  acid  of  the  air.  This  result  of  weather- 
ing makes  resistant  minerals  turn  to  sources  of  fertility,  as  the 
alkaline  carbonates  thus  liberated  are  necessary  to  plants.  A  proc- 
ess imperceptible  in  any  laboratory  experiment,  with  the  small 
mass  of  carbonic  acid  ordinarily  engaged,  becomes  on  the  large 
scale  of  nature  and  in  geologic  time  a  reaction  of  great  importance, 
owing  to  the  enormous  quantities  of  carbonic  acid  in  the  air  and 
surface  waters  unceasingly  at  work. 


208  NON-METALS 

BORON 

Symbol,  B.     Atomic  weight,  u. 

Properties. — Boron  is  a  triad  element  which  is  never  native, 
but  is  found  united  with  oxygen  and  sodium  as  borax;  and  with 
oxygen  alone  as  boron  trioxid.  It  occurs  in  three  modifications: 

Amorphous  boron — a  dull  gray  powder  which,  when  strongly 
heated  in  air,  burns  to  boric  oxid,  B2O3. 

Graphitoidal  boron,  in  scales  with  graphite-like  luster. 

Diamond  boron  is  square  octahedra  of  cupreous  luster;  hard 
enough  to  scratch  a  ruby. 

Boron,  when  heated  strongly  in  chlorin  or  oxygen,  takes  fire, 
forming  a  chlorid  or  oxid.  It  is  remarkable  as  being  one  of  the 
few  elements  uniting  directly  with  nitrogen,  which  gas  it  absorbs 
when  red  hot  with  the  evolution  of  light,  forming  boron  nitrid,  BN. 
Boron  with  chlorin  forms  a  liquid  called  boron  trichlorid,  BC13; 
with  hydrogen  a  trihydrid,  BH3. 

Boron  Trioxid,  Boric  Anhydrid  (B2O3).— This  compound 
fuses  to  a  glass,  which  retains  its  clearness  on  cooling.  It  is  pre- 
pared by  heating  boric  acid,  H3BO3: 

2H3B03  3H20         +         B203. 

By  reversing  the  reaction  with  water  B2O3  forms  boric  or  boracic 
acid,  H3BO3. 

Boric  acid  is  a  tribasic  weak  acid,  crystallizing  in  pearly 
plates  from  a  hot  solution  as  it  cools.  It  is  found  in  the  fumerolles 
(steam  jets)  which  are  constantly  escaping  from  the  earth  in  old 
volcanic  districts  of  Tuscany,  and  in  the  lagoons  which  collect  at 
the  mouth  of  these  jets.  The  boric  acid  is  concentrated  by  the 
heat  of  the  natural  steam  jets,  and  is  finally  obtained  pure  by 
crystallization.  Sodium  borate  also  occurs  in  California  and 
Thibet. 

Preparation. — Boric  acid  may  be  prepared  by  the  action  of 
hydrochloric  acid  on  a  hot  solution  of  borax,  Na2B4O7: 

Na2B407     +     2HC1     +     sH20     =     2NaCl     +     4H3BO3. 

A  10  per  cent,  ointment  is  official. 

Borax  is  the  salt  most  largely  used  in  the  arts. 

Borax  (Na2B4O7ioH2O)  (Biborate  of  Soda).— This  substance  is 
a  native  salt,  but  can  be  artificially  prepared  by  heating  together 
boric  acid  and  sodium  carbonate: 

4H3BO3     +     Na2CO3     =     6H2O     +     CO2     +     Na2B4O7. 


BORON  209 

Borax  is  a  salt  of  a  tetraboric  acid,  formed  from  the  normal 
acid,  H3BO3,  by  loss  of  water.  Thus:  4H3BO3  deprived  of  5H2O 
yields  H2B4O7.  Borax  is  much  used  as  a  blow-pipe  reagent  in 
the  laboratory,  since  many  metallic  oxids  are  soluble  in  fused 
borax,  yielding  colored  glasses.  It  is  also  used  as  a  flux  to  clean 
metals  when  they  are  to  be  soldered  with  hard  solder. 

Its  solution  has  an  alkaline  reaction  and  is  largely  used  in 
medicine  locally  to  destroy  bacteria. 

Liquor  antisepticus  (U.  S.  P.)  is  a  solution  of  boric  acid,  benzoic 
acid,  and  thymol  in  a  diluted  tincture  of  antiseptic  aromatics. 

Toxicology  of  Boric  Acid  and  Borax.— The  local  effect  of 
boric  acid  being  very  mild,  its  virtues  as  a  bactericide  have  led  to 
its  use  in  surgical  practice,  especially  for  washing  out  cavities  and 
sinuses  to  prevent  septic  changes.  Cases  are  recorded  of  depres- 
sion and  eruptions  of  erythema  and  urticaria  following  its  absorp- 
tion from  wounds  and  cavities  when  used  too  freely.  Occasionally, 
graver  phenomena  have  appeared,  such  as  vomiting,  diarrhea, 
bloody  urine,  and  collapse.  Fatal  results  have  ensued  in  a  few 
cases  from  injecting  the  solution  into  the  abscess  sacs  and  from 
washing  out  the  stomach  with  it. 

The  toxicology  of  boric  acid  and  borax  is  limited  practically  to 
the  use  of  these  agents  as  preservatives  of  food.  They  destroy  the 
germs  of  fermentation  and  putrefaction  in  solid  and  liquid  foods. 
For  meats  they  are  often  mixed  with  salicylic  acid  and  applied  ex- 
ternally. For  preserving  milk  it  is  a  common  practice  to  add  to 
i  qt.  of  milk  10  gr.  of  a  mixture  of  equal  parts  of  borax  and  boric 
acid. 

Experiments  upon  men,  conducted  by  the  U.  S.  Agricultural 
Bureau,  proved  that  "both  boric  acid  and  borax,  when  contin- 
uously administered  in  small  doses  for  a  long  period,  or  when 
given  in  large  quantities  for  a  short  period,  create  disturbances  of 
appetite,  of  digestion,  and  of  health."  Even  in  the  small  amounts 
required  for  preserving  cream  and  butter,  and  that  used  as  an 
external  dust  on  hams  and  bacon,  which  have  to  be  transported 
long  distances,  both  boric  acid  and  borax  are  objectionable  from 
a  sanitary  standpoint,  unless  the  food  substances  are  frankly 
labeled  as  preserved. 

As  these  substances  are  not  normal  constituents  of  the  body, 
it  is  best  to  avoid  their  use,  since  the  most  conclusive  evidence  has 
been  adduced  that  they  are  not  free  from  harm  in  the  amounts 
as  commonly  used  for  preserving  food. 

Detection  of  Boric  Acid  in  Meat. — Jorgenserts  test  makes  use 

of  the  property  of  neutralized  boric  acid  to  take  on  an  acid  reaction 

after  treatment  with  glycerin.     The  meat  is  made  strongly  alkaline 

with  sodium  hydroxid,  extracted  with  hot  water  for  several  hours, 

14 


210  THE    METALS 

and  the  extract  filtered.  The  filtrate  is  evaporated  to  dryness, 
incinerated,  and  the  ash  dissolved  in  sulphuric  acid,  by  warming 
the  carbon  dioxid  is  removed,  and  on  cooling  the  solution  is  neutral- 
ized by  an  alkaline  hydroxid,  using  phenolphthalein  as  indicator. 

To  50  c.c.  of  the  neutral  fluid  25  c.c.  of  glycerin  are  added, 
and  the  mixture  titrated  with  decinormal  sodium  hydroxid  solu- 
tion without  regard  to  the  phosphates.  The  end-reaction  is  made 
more  definite  by  the  addition  of  ethyl  alcohol. 

Detection  in  Milk. — Turmeric  Test. — Place  in  a  porcelain  dish 

1  drop  of  the  milk  with  2  drops  of  strong  hydrochloric  acid  and 

2  drops  of  a  saturated  turmeric  tincture.     Dry  this  on  a  water- 
bath,  cool,  and  add  a  drop  of  ammonia  by  means  of  a  glass  rod. 
A  slaty-blue  color  changing  to  green  is  produced  if  borax  is  present. 
A  drop  of  milk  containing  TWO"  gr-  °f  borax  will  give  this  reaction. 

Flame  Test. — With  alcohol  boric  acid  forms  a  volatile  ester 
which  burns  with  a  green  flame.  Material  suspected  of  containing 
boric  acid  is  put  in  a  capsule  and  covered  with  sulphuric  acid. 
Alcohol  is  poured  over  the  mixture,  which  is  heated  until  it  takes 
fire.  The  green  color  is  very  characteristic. 


THE  METALS 

THE  metals  are  easily  recognized  by  properties  common  to  all 
and  illustrated  in  well-known  examples,  such  as  gold,  silver,  cop- 
per, and  lead.  All  except  mercury  are  solid  at  ordinary  temper- 
ature. They  conduct  well  both  heat  and  electricity,  and  many 
can  be  polished  so  as  to  reflect  light,  this  quality  being  described 
as  metallic  luster.  Most  of  them  are  dense  and  heavy,  can  be 
drawn  into  wires  (ductile),  hammered  into  thin  plates  (malleable), 
and  resist  attempts  to  break  them  (tenacious).  All  are  opaque 
except  when  reduced  to  the  thinnest  films,  such  as  gold-leaf. 
When  metals  combine  among  themselves  they  make  alloys;  if  the 
union  be  with  mercury,  it  is  called  an  amalgam.  These  combina- 
tions are  not  attended  by  loss  of  metallic  character. 

When  solutions  of  metallic  salts  are  put  in  electrolytic  cells 
the  metals  invariably  seek  the  negative  pole,  and  hence  are  cations. 

In  the  present  work  a  classification  is  adopted  deemed  suitable 
for  the  needs  of  the  medical  student.  The  resemblances  which 
are  emphasized  and  which  form  the  basis  of  the  groups  are  such 
as  have  significance  growing  out  of  their  medical  or  toxic  rela- 
tions. Several  very  different  arrangements  are  possible,  which 
might  be  regarded  as  more  suggestive  and  more  helpful  to  the 


METALS    OF    THE    ALKALIS  211 

non-medical  students  of  chemistry,  because  they  include  a  greater 
number  of  analogies.  One  of  these  is  the  natural  system  referred 
to  on  p.  116. 

The  important  metals  will  be  considered  in  the  order  of  the 
following  groups,  the  lightest  metals  presenting  the  highest  powers 
of  uniting  with  oxygen: 

I.  Alkali  metals  :  oxids  and  most  salts  soluble.            "I  Light  metals  with  spe- 
ll. Alkaline  earth  metals :  oxids  soluble,  carbonates    I  cific  gravity  not  ex- 
insoluble.  ceeding4.   Sulphids 

III.  Earth  metals  :  oxids  insoluble.                                    J  soluble  in  water. 

IV.  Arsenic  group :  sulphids  insoluble  in  dilute  acids,  "] 

but  soluble  in  ammonium  sulphid.  „  .  ,          .t, 

V.  Copper  group  :   sulphids  insoluble  in  dilute  acids,  | 

and  in  ammonium  sulphid.  \-       sPec\nc   gravity  ex 
VI.  Iron  group  :  sulphids  soluble  in  dilute  acids.  Ceding  4.   Sulphids 

VII.  Gold  group  :  sulphids  insoluble  in  dilute  acids,  '  m  water' 

but  soluble  in  ammonium  sulphid. 


THE  LIGHT  METALS 
L— THE  METALS  OF  THE  ALKALIS 

Potassium,  K.  Ammonium,  NH4,  hypothetic. 

Sodium,  Na.  Cesium,  Cs. 

Lithium,  Li.  Rubidium,  Rb. 

The  members  of  this  group  are  all  univalent,  some  of  them 
are  lighter  than  water,  and  nearly  all  of  their  compounds  are 
soluble  in  water.  They  never  occur  free  in  nature,  because  of 
their  great  power  of  forming  compounds.  This  also  makes  it 
necessary  to  resort  to  unusual  precautions  to  protect  them  from 
such  union.  Their  oxids,  hydroxids,  and  carbonates  are  alkaline 
in  reaction.  None  of  the  group  reagents  has  any  visible  effect 
upon  solutions  of  the  salts  belonging  to  this  group.  Their  chlo- 
rids  and  sulphids  are  all  soluble  and,  therefore,  are  not  precip- 
itated by  hydrochloric  acid,  hydrogen  sulphid,  or  ammonium 
sulphid.  Unlike  the  alkaline  earths,  they  (except  lithium)  are 
not  precipitated  by  ammonium  carbonate. 

Corrosive  Alkalies.— Under  this  heading  will  be  considered 
the  hydroxids  or  hydrates  of  potassium,  sodium,  and  ammonium. 
It  is  well  to  note  that  their  basic  carbonates  also  are  not  only  strongly 
alkaline  in  reaction,  but  in  concentrated  solution  have  a  corrosive 
effect.  The  action  of  the  corrosive  alkalies  is  chemical  or  local, 
and  limited  to  the  part  with  which  they  come  in  contact.  This 
corrosive  power  is  due  to  their  solvent  action  on  albumin,  their 
saponifying  property  when  mixed  with  fatty  matter,  and  their 
avidity  for  the  water  of  the  tissues.  They  cause  rapid  and  deep 
destruction  of  the  animal  structures.  The  local  symptoms  are 


212  THE    METALS 

like  those  of  corrosive  acids.  The  general  symptoms  are  likewise 
those  of  the  shock  of  a  violent  lesion  added  to  the  immediate 
consequences  of  the  lesion  due  to  its  locality.  Poisoning  from  them 
is  most  often  accidental,  though  they  are  not  infrequently  taken 
with  suicidal  intent. 

POTASSIUM   (Kalitim) 
Symbol,  K.     Atomic  weight,  39.14. 

Occurrence. — Potassium  is  found  in  nature  in  its  compounds 
only.  Among  these  are  saltpeter,  feldspar,  and  carnallite.  The 
disintegration  of  feldspar  by  the  weather  furnishes  the  soil  with 
potash  in  a  form  assimilable  by  plants,  required  by  them  for  their 
growth,  they  in  turn  furnishing  it  in  vegetable  food  to  animals. 
In  small  quantities  potassium  is  indispensable  to  the  animal 
organism,  being  a  constituent  of  the  red  blood-corpuscles.  When 
greatly  concentrated  many  of  its  salts  act  as  irritants  or  cor- 
rosives. Even  if  diluted,  the  continuous  administration  of  these 
salts  in  full  doses  brings  about  anemia,  loss  of  energy,  and  other 
indications  of  impaired  nutrition.  This  toxic  action  is  attributable 
to  the  potassium  ion  in  the  blood  in  excess  of  the  physiologic 
need. 

The  ashes  of  wood,  leached  with  water,  yield  potassium  car- 
bonate; the  water  evaporated  by  boiling  leaves  crude  potash, 
formerly  the  chief  source  of  the  other  compounds. 

Preparation. — Potassium  is  now  prepared  by  decomposing 
the  hydroxid  or  chlorid  by  electricity,  K',C1'=K  +  C1.  The 
older  chemical  method  was  to  heat  potassium  carbonate  with 
charcoal.  The  carbonate  yields  oxygen  to  the  reducing  carbon 
to  form  the  gas  carbon  monoxid,  and  the  metal  is  vaporized  to 
condense  under  petroleum.  Thus: 

K2CO3          +          2C  2K          +          3CO. 

Properties. — Freshly  cut  surfaces  of  potassium  show  a  silver- 
white  luster.  At  ordinary  temperatures  it  is  soft,  like  wax,  and 
can  be  molded  by  the  ringers.  At  a  red  heat  it  passes  into 
a  blue-green  vapor.  It  combines  with  oxygen  with  so  much 
velocity  that  it  decomposes  water  violently,  and,  exposed  to  the 
air,  tarnishes  immediately.  For  protection  potassium  must  be 
kept  under  petroleum  or  in  hydrogen  gas.  In  time,  even  in  coal- 
oil,  it  unites  with  some  dissolved  oxygen  and  becomes  covered 
with  a  gray-brown  crust,  which,  however,  shields  the  deeper  parts. 

Potassium  Dioxid  (KO2).— This  is  prepared  by  heating 
potassium  in  oxygen.  It  is  an  orange-colored  powder  used  to 
form  hydrogen  dioxid. 

2KO2     +     2H2O     -     2KOH     +     H2O2     +     O2. 


POTASSIUM  2 13 

Potassium  Hydroxid  (KOH)  (Potassium  Hydrate,  Caustic 
Potash}. — Preparation. — When  thrown  upon  water,  a  piece  of 
potassium  floats  about  on  the  surface,  melts,  forms  a  silvery  ball, 
bursts  into  a  reddish-violet  flame,  and  grows  red  hot.  As  the 
metal  is  consumed  the  flame  goes  out,  the  incandescent  ball  of 
hydroxid  cools  down  to  the  point  when  wetting  is  possible,  and 
then  dissolves  with  such  a  sudden  evolution  of  heat  that  a  steam 


FIG.  59. — Potassium  decomposing  water. 

explosion  occurs.  The  violet  or  lavender  flame  is  hydrogen  ignited 
by  the  heat  of  chemical  action  and  colored  by  particles  of  potas- 
sium (Fig.  59). 

H20         +          K  KOH          +          H. 

Commercially  it  is  manufactured  by  first  electrolyzing  potassium 
chlorid,  using  a  cathode  of  mercury.  The  mercury  makes  an 
amalgam  with  the  potassium,  and  the  amalgam,  in  contact  with 
water,  forms  the  hydroxid,  the  free  mercury  being  again  ready  for 
use  as  a  cathode. 

If  mercury  be  not  used  as  a  cathode,  the  movement  of  the  ions 
occurs  in  the  sense  of  the  following  equation: 

K',C1'  +     H',(OH)'  H     +      Cl     +      K-,(OH)'. 

The  chlorin  ions  give  up  their  charge  at  the  anode  and  escape 
as  gas.  The  potassium  ions  seek  the  cathode  with  a  strong  charge; 
there  they  find  some  of  the  weakly  dissociated  hydrogen  ions  of 
the  water,  which  discharge  upon  the  cathode  and  are  set  free  as 
gas.  The  remaining  hydroxyl  anions  are  held  in  relation  to  the 
potassium  cations  as  potassium  hydroxid  in  solution. 

The  older  method  of  preparation  was  to  decompose  potassium 
carbonate  with  calcium  hydroxid  in  weak  solution.  The  reaction 
is  expressed  thus: 

K2CO3     +      Ca(HO)2     =      CaCO3     +      2KOH. 

The  calcium  carbonate  is  precipitated,  and  the  potassium  hydroxid 
is  separated  by  boiling  off  the  water  of  the  filtered  solution. 


214  THE    METALS 

Properties. — The  pure  substance  is  a  gray-white  solid  with  an 
angular  fracture.  It  imparts  a  soapy  feeling  when  handled,  has 
a  soapy  taste,  and  a  strong  alkaline  reaction  to  litmus.  Heated, 
it  melts  to  a  colorless  liquid;  run  into  cylindric  molds  it  makes 
potassa  jusa,  the  ordinary  form  seen  in  shops.  It  dissolves  in 
half  its  weight  of  water,  evolving  heat;  it  is  soluble  also  in 
alcohol  and  glycerin,  but  insoluble  in  ether.  It  deliquesces 
rapidly,  and  in  the  moist  state  freely  takes  up  carbon  dioxid  gas 
to  make  potassium  carbonate.  It  is  a  typical  base,  dissociating 
strongly  and  developing  in  a  high  degree  the  alkaline  properties 
of  hydroxidion.  A  very  small  quantity  in  solution  makes  litmus 
blue  and  phenolphthalein  red. 

Pharmaceutic  Preparation. — Potassii  hydroxidum  occurs  in 
cylindric  rods.  Liquor  potassii  hydroxidi  (U.  S.  P.  )  is  a  color- 
less, acrid,  alkaline,  corrosive  liquid  with  a  specific  gravity  of 
1.036,  and  containing  about  5  per  cent,  of  potassium  hydroxid. 
Potassa  cum  calce  (Vienna  paste)  is  made  of  equal  parts  of  potassa 
and  quicklime.  The  two  carbonates  resemble  the  hydroxid  in 
toxic  effects,  but  differ  in  degree.  Potassii  carbonas  impura  -(pearl- 
ash),  under  the  name  of  potashes,  used  for  cleansing  oil-lamps, 
occurs  as  a  dark  mass,  deliquescent,  strongly  alkaline,  and  caustic. 
Potassii  carbonas  pura  occurs  as  white  crystals,  deliquescent, 
alkaline,  and  caustic. 

Symptoms. — Taken  in  strong  solution,  a  large  dose  of  caustic 
potash  or  the  carbonate  will  cause  a  nauseous,  soapy  taste,  accom- 
panied by  burning  pain  in  the  mouth,  throat,  and  stomach.  Vomit- 
ing of  alkaline  bloody  material  soon  follows,  and  later  colicky 
pains  and  great  abdominal  tenderness  with  purging  of  shreds  of 
epithelium,  mucus,  and  blood.  The  lips  and  tongue  swell  and 
turn  brown,  swallowing  is  difficult,  and  the  skin  cold  and  damp,  the 
breathing  hurried  and  shallow.  Surviving  these  symptoms,  the 
patient  may  die  after  some  days  of  starvation  from  stricture  of  the 
gullet. 

Fatal  Dose. — The  ordinary  fatal  quantity  is  J  oz.  (15.5  gm.), 
but  30  gr.  (2  gm.)  have  proved  sufficient. 

Fatal  Period. — From  the  acute  effects  death  may  come  in  three 
hours;  from  the  secondary  effects  the  final  event  may  be  delayed 
for  weeks  or  even  years.  The  average  duration  is  about  twenty- 
four  hours. 

Treatment. — The  local  action  of  the  poison  should  be  lessened 
by  copious  drafts  of  water,  alone  or  acidulated.  The  chemical 
antidotes  are  weak  acids  and  oils.  The  most  convenient  weak 
acid  is  vinegar,  but  diluted  lemon-juice  or  orange-juice  will  serve. 
Milk,  olive  oil,  melted  butter,  or  lard  would  also  neutralize  the 
alkalis,  though  not  so  promptly.  The  stomach-pump  is  not  admis- 


POTASSIUM  215 

sible.  The  pain  will  call  for  morphin  injections;  collapse  should 
be  met  by  stimulants,  and  threatened  starvation  by  nutritive 
enemata. 

Postmortem  Appearances. — The  mouth,  throat,  and  gullet  are 
whitish  and  softened.  The  stomach  and  intestines  are  bright  red 
or  black  from  extravasated  blood;  the  lining  membrane  dis- 
organized and  stripped  in  patches.  The  secondary  pathologic 
changes  seen  when  death  closes  the  history  of  a  chronic  case  are 
denudation  of  the  lining  membrane,  ulceration,  and  points  of 
stricture  in  gullet  or  pylorus. 

Detection. — As  alkalinity  of  the  gastric  contents  has  never  been 
reported  in  any  normal  case,  the  mere  fact  that  vomited  matters 
or  gastric  contents  have  an  alkaline  reaction  would  be  so  excep- 
tional as  to  be  suspicious.  After  separating  the  soluble  alkali 
from  the  undissolved  matter  by  dialysis,  the  clear  liquid  should 
be  titrated  with  decinormal  sulphuric  acid  and  tested  for  potassium 
(see  p.  222).  As  the  chlorid,  sulphate,  and  phosphate  of  the  metal 
are  natural  constituents  of  the  food  and  of  the  body  itself,  more  or 
less  of  these  will  be  found  always  present.  Hence  if  the  fluid  is 
not  alkaline,  the  process  must  include  quantitative  determinations 
of  the  different  metals.  If  the  analyst  can  obtain  a  sample  of  the 
substance  taken  or  a  piece  of  the  clothing  stained,  his  task  is 
much  simpler. 

Potassium  chlorid  (KC1)  is  found  in  Germany  in  the  mineral 
carnallite.  It  is  a  double  chlorid  of  magnesium  and  potassium. 
To  obtain  the  potassium  chlorid  from  this  mineral  a  hot  solution 
is  made,  which  on  cooling  separates  the  potassium  chlorid  as 
crystals. 

Properties. — Potassium  chlorid  forms  white  cubic  crystals  much 
more  soluble  in  hot  water  than  in  cold.  It  is  typical  of  the  salts 
formed  by  a  strong  acid,  HC1,  acting  on  a  strong  base,  KHO, 
and  in  solution  its  ions  are  completely  dissociated. 

Potassium  bromid,  KBr,  can  be  formed,  as  other  bromids, 
by  the  direct  action  of  bromin  on  the  metal,  though  the  more  con- 
venient method  is  action  on  the  hydroxid: 

6KOH     +   6Br       =      5  KBr      +      KBrO3     +   3H2O. 

Properties. — It  crystallizes  in  white  cubes  without  odor,  but 
with  a  salty  and  nutty  taste.  It  is  soluble  in  about  2  parts  of 
water,  4  of  glycerin,  but  requires  200  of  alcohol.  Its  solution  is 
a  convenient  source  of  bromin  ions.  Dose:  15  to  60  gr.  (1-4 
gm.),  repeated.  If  long  continued,  there  is  danger  of  inducing 
bromism  (see  p.  144).  It  is  incompatible  with  acids,  alkaloids,  and 
the  salts  of  silver,  mercury,  lead,  copper,  bismuth,  and  antimony. 


2i6  THE    METALS 

Potassium  iodid,  KI,  is  prepared  by  a  reaction  between 
potassium  hydroxid  and  ferrous  iodid: 

FeI2       +        2KOH       =       Fe(OH)2       +        2KI. 

The  ferrous  hydroxid  is  precipitated,  the  potassium  iodid  remains 
in  the  nitrate. 

Properties. — It  occurs  in  white  cubes  of  a  bitter,  salty  taste, 
soluble,  1.27  parts  in  i  of  water,  in  glycerin  i  part  to  3,  in  alcohol  i 
to  18.  Dose:  3  to  30  gr.  (0.19-1.9  gm.),  repeated.  Care  should  be 
observed  lest  iodism  be  induced  (see  p.  147).  The  ion  of  iodin  is 
well  represented  in  the  aqueous  solution.  It  is  incompatible  with 
acids,  metallic  salts  (especially  silver  nitrate,  calomel,  and  potas- 
sium chlorate),  chloral  hydrate,  and  salts  of  alkaloids. 

Potassium  chlorate  (KC1O3)  is  obtained  when  chlorin  acts 
on  potassium  hydroxid: 

6KOH     +     6C1     =     sKCl     +     KC1O3     +     3H2O. 

Of  the  two  salts  the  chlorate  is  less  soluble,  and  on  evapora- 
tion of  the  mixed  solution  it  crystallizes  first. 

Properties. — Its  crystals  are  beautiful  white  plates  with  a  cool 
saline  taste,  soluble  in  about  17  parts  of  water,  insoluble  in  alco- 
hol. In  the  laboratory  it  is  chiefly  valuable  as  a  store  of  oxygen, 
which  it  readily  yields  on  heating.  Dose:  10  to  20  gr.  (0.64- 
1.29  gm.),  diluted,  after  meals.  Tablets  for  sore  mouth,  5  gr. 
each.  It  is  incompatible  with  tartaric  acid  and  ferrous  iodid.  It 
is  likely  to  explode  when  rubbed  in  a  mortar  with  sugar,  sulphur, 
or  phosphorus. 

This  salt  is  much  used  in  the  manufacture  of  explosives  and 
flashing  powders,  and  in  medicine.  In  the  household  it  is  a  com- 
mon remedy  for  sore  mouth  and  throat,  and  through  a  belief  in 
its  harmlessness,  often  leads  to  injury. 

Symptoms. — If  used  as  a  mouth- wash  it  is  harmless,  but  when 
swallowed  in  large  doses  it  is  irritant,  causing  abdominal  pain, 
vomiting,  diarrhea,  and  even  collapse.  A  case  of  poisoning  has 
been  reported  from  two  teaspoonfuls  taken  in  two  days  for  sore 
throat.  It  caused  violent  intestinal  irritation,  with  black  stools, 
considerable  urinary  disturbance,  with  black  urine,  great  prostra- 
tion, and  evidences  of  grave  alteration  of  the  blood. 

When  absorbed,  it  has  a  peculiar  destructive  action  on  the  red 
corpuscles  of  the  blood,  converting  the  hemoglobin  into  methemo- 
globin  and  setting  up  secondary  symptoms,  such  as  jaundice, 
hemoglobinuria,  suppression  of  urine,  bloody  tube-casts,  delir- 
ium, coma,  and  death  as  a  consequence  of  the  acute  nephritis. 


POTASSIUM  217 

Fatal  Dose  and  Period. — Forty-six  grains  (2.9  gm.)  proved  a 
fatal  dose  in  a  child  three  years  old.  The  minimum  adult  dose 
reported  as  fatal  is  3  dr.  (11.65  gm-)-  Fountain  took  ij  oz.  with 
fatal  consequences  in  seven  days.  If  a  certain  amount  is  given 
in  divided  doses,  the  effect  is  more  severe  than  when  given  in  a 
single  dose.  Death  has  occurred  in  five  hours,  but  usually  it 
results  from  nephritis  after  several  days. 

Treatment. — Having  washed  out  the  stomach  with  the  tube  or 
pump,  the  secondary  effects  must  be  combated  with  appropriate 
remedies.  The  kidney  complications  will  require  active  local 
treatment. 

Postmortem  Appearances. — The  marks  of  gastro-enteritis  will 
be  found — i.  e.,  a  mucous  membrane  reddened,  thickened,  and 
easily  detached.  Inflammatory  changes  are  seen  in  the  spleen, 
liver,  and  especially  in  the  kidneys.  These  organs  are  enlarged 
and  dark  brown  in  color,  from  the  presence  of  the  altered  hemo- 
globin. 

Detection. — As  the  salt  is  unchanged  in  the  body,  it  can  easily 
be  separated  from  organic  matter  by  dialysis.  Having  colored 
the  suspected  solution  with  indigo  sulphate  and  acidulated  with 
dilute  sulphuric  acid,  the  addition  of  sulphurous  acid  will  discharge 
the  blue  color  if  the  chlorate  be  present. 

Potassium  nitrate  (KNO3)  (saltpeter,  niter)  is  found  in  the 
soil  of  India  and  can  be  procured  by  leaching  with  water.  It  is 
also  formed  artificially  in  " plantations"  of  bacteria.  Nitrogenous 
waste  of  animals  mixed  with  the  potassium  carbonate  of  wood 
ashes  make  a  soil  for  the  growth  of  the  nitrifying  bacteria.  These 
ferments  cause  the  ammonia  of  putrefaction  to  be  oxidized  to  nitric 
acid,  which  unites  with  the  potassium  of  the  wood  ashes  to  form 
KNO3.  After  several  years  the  fermenting  material  is  leached 
and  the  crude  nitrate  dissolves  out,  to  be  purified  by  crystalliza- 
tion. Like  the  chlorate,  this  salt  is  a  liberal  oxidizer. 

The  chief  source  now  is  double  decomposition  of  "  Chili  salt- 
peter," sodium  nitrate,  and  potassium  chlorid: 

NaNO3     +     KC1     =     KNO3     +     NaCl. 

Hot  saturated  solutions  are  used  which  retain  KNO3,  but  separate 
the  less  soluble  NaCl.  This  leaves  a  liquid  which  on  cooling  yields 
crystals  of  KNO3. 

In  100  parts  of  gunpowder  there  are  of  KNO3  75  parts;  sul- 
phur, 12  parts;  carbon,  13  parts.  Owing  to  the  intimacy  of  the 
mixture,  combustion  is  immediate  and  complete. 

Properties. — It  forms  large  hexagonal  prisms,  permanent  in  the 
air.  Without  odor,  they  have  a  cool  saline  taste,  and  are  soluble 
in  4  parts' of  water.  Dose:  10  to  60  gr.  (0.65-4  gm.). 


2l8  THE    METALS 

Under  the  name  sal  prunelle  potassium  nitrate  is  found  to  be 
molded  in  small  balls.  It  is  used  as  a  remedy  for  the  diseases  of 
cattle;  also  in  the  preservation  of  the  original  reddish  color  of 
salted  meat  and  in  the  manufacture  of  explosives.  In  the  crystal- 
line form  it  has  been  taken  as  a  purgative  by  mistake  for  mag- 
nesium sulphate  in  8  cases.  In  2  cases  it  has  been  mistaken  for 
common  salt. 

Symptoms. — While  doses  of  i  dr.  (4  gm.)  cause  minor  degrees 
of  gastric  and  intestinal  irritation,  doses  of  from  \  to  i  oz.  (16- 
32  gm.)  excite  acute  gastro-enteritis.  There  are  vomiting,  abdom- 
inal pain,  diarrhea,  perhaps  bloody  in  character,  localized 
muscular  spasms,  disturbed  respiration  and  heart  action,  and  col- 
lapse. 

Fatal  Dose. — Though  an  adult  has  died  from  the  effects  of 
2  dr.,  other  cases  have  recovered  from  a  dose  of  i  oz. 

Fatal  Period. — Two  hours  is  the  shortest  period  in  which  death 
has  taken  place;  the  average  duration  of  fatal  cases  is  somewhat 
longer. 

Treatment. — The  stomach  must  be  evacuated  by  emetics,  and 
the  stomach-pump  or  tube  used  to  wash  out  the  poison.  Bland 
demulcents  may  be  administered,  and  the  tendency  to  collapse 
overcome  by  stimulants  and  warm  applications. 

Detection. — As  nitrates  are  not  present  in  the  body,  the  presence 
of  a  notable  quantity  in  the  gastric  contents  or  other  organic 
mixture  would  be  significant.  By  adding  sulphuric  acid  the 
nitric  acid  is  freed  and  the  tests  for  the  acid  can  be  applied  (see 
p.  172). 

Copper  Tests.— Heated  in  a  test-tube  with  sulphuric  acid 
and  copper  turnings,  nitrates  evolve  red  fumes  of  nitrogen  oxids. 

Brucin  Test. — Mixed  with  an  equal  volume  of  sulphuric  acid, 
a  nitrate  solution  produces  a  tint  of  carmin  on  the  addition  of  a 
trace  of  brucin. 

Potassium  Nitrite  (KNO2,  H2O).— This  is  formed  when 
part  of  the  oxygen  of  potassium  nitrate  is  liberated  by  heating: 

2KNO3     =      2KNO2     +      O2. 

When  the  nitrate  is  employed  to  oxidize  metals,  such  as  lead, 
the  nitrite  is  also  obtained  as  the  reduced  salt: 

KN03     +     Pb     =      KN02     +     PbO. 

The  aqueous  solution  of  this  salt  of  a  weak  acid  is  alkaline 
from  the  preponderance  of  hydroxyl  ions  caused  by  the  hydro- 
lysis, the  acid  being  almost  undissociated: 

K-,  (N02)'     +     H20     =      K-,  (OH)'     +     HNO,. 


POTASSIUM  219 

The  nitrous  acid,  HNO2,  is  set  free  in  solution  when  sulphuric 
acid  is  added  to  a  solution  of  potassium  nitrite.  Its  anhydrid  is 
N2O3. 

Potassium  hydrosulphid,  KHS,  is  formed  by  saturating  a 
solution  of  potassium  hydroxid  with  the  gas  hydrogen  sulphid: 

KOH     +     H2S     =     H2O      +      KHS. 

As  a  salt  of  sulphydric  acid,  which  is  weak  in  its  acid  proper- 
ties, hydrolytic  dissociation  occurs,  forming  hydroxidion  in  amounts 
dominating  the  hydrion,  which  is  scarcely  dissociated  from  the 
acid,  and,  therefore,  making  an  alkaline  solution.  Thus: 

K-,  (HS)'     +     H2O     =      K-,  (HO)'     +     H',  (HS)'. 

Potassium  monosulphid,  K2S,  as  a  hydrolyzed  alkaline  solu- 
tion, is  obtained  by  adding  potassium  hydroxid  to  potassium 
hydrosulphid: 

KHS     +      KOH     =      K2S     +     H20. 

Four  other  sulphids  are  known,  the  higher  polysulphids  being 
interesting  as  components  of  the  medicinal  compound.  Potassii 
sulphuratum,  hepar  sulphuris,  or  liver  of  sulphur,  is  the  product 
obtained  by  fusing  together  potassium  carbonate  and  sulphur. 
It  is  a  brownish-yellow  mixture  of  sulphids,  varying  in  composi- 
tion between  the  trisulphid,  K2S3,  and  the  pentasulphid,  K2S5. 
Dose:  J  to  5  gr.  (0.03-0.3  gm.). 

Potassium  sulphate,  K2SO4,  occurs  in  combination  with 
magnesium  chlorid  in  the  mineral  kainite,  and  also  in  mineral 
waters.  Its  hard  prismatic  crystals  have  a  bitter,  salty  taste,  are 
permanent  in  the  air,  and  are  soluble  in  10  parts  of  water.  It  is 
a  laxative  in  doses  of  15  to  75  gr.  (1-5  gm.)  in  solution.  In  ex- 
cessive doses  it  has  proved  poisonous,  causing  abdominal  pain, 
vomiting,  purging,  exhaustion,  and  fatal  collapse.  There  is  no 
specific  antidote.  The  stomach  should  be  evacuated  and  the 
irritation  and  depression  treated  as  they  arise. 

Potassium  Acid  Sulphate,  or  Potassium  Bisulphate  (KHSO4). 
— This  is  obtained  as  a  by-product  in  the  manufacture  of  nitric 
acid.  It  is  formed  when  the  normal  sulphate  is  treated  with 
more  sulphuric  acid;  hence  the  name  bisulphate. 

K2S04     +     H2S04     =      2KHS04. 

Its  colorless,  moist  plates  are  freely  soluble  in  water,  making 
a  strongly  acid  solution.  This  reaction  is  caused  by  the  strong 


220  THE    METALS 

acid,  H2SO4,  dissociating  to  a  slight  extent  its  unreplaced  hydrogen. 
Thus: 

KHS04       =        K-,  H-,  (S04)". 

Potassium  bisulphate  is  used  in  medicine  as  an  aperient  tonic. 
Dose:  60  to  120  gr.  (3-5  gm.). 

Potassium  Sulphite  (K2SO3).— This  is  formed  by  saturating 
with  sulphur  dioxid  a  solution  of  potassium  carbonate  or  hydroxid. 
Evaporating  the  solution  over  sulphuric  acid,  the  sulphite  is 
obtained  crystallized  in  rhombohedra.  These  crystals  are  soluble 
in  water,  and  in  solution  change  to  K2SO4  by  absorbing  oxygen 
from  the  air.  The  pyrosulphite,  K2S2O5,  oxidizes  very  slowly  in 
air  and  is  employed  in  photography.  In  water  it  makes  an  acid- 
sulphite  solution  containing  the  ions  K*  and  (HSO3)'. 

Potassium  carbonate,  K2CO3,  occurs  in  the  animal  body 
and  in  mineral  waters.  For  many  years  it  was  produced  by  leach- 
ing with  water  the  ashes  of  plants,  and  then  boiling  off  the  water. 
The  impure  potash  or  pearlash  was  purified  by  solutions  and  crys- 
tallizations, so  as  to  make  pure  potassium  carbonate.  The  modern 
method  of  preparation  is  to  electrolyze  potassium  chlorid;  the 
hydroxid  forming  in  the  liquid  around  the  cathode.  Carbon 
dioxid  is  passed  into  the  hydroxid  solution,  forming  potassium 
carbonate. 

Properties. — It  is  a  white  granular  powder,  deliquescent  and 
remarkably  soluble  in  water.  At  low  temperatures,  by  evapora- 
tion, a  salt  crystallizes  with  the  formula  2K2CO3,  3H2O. 

Owing  to  the  weakness  of  carbonic  acid,  there  is  an  interchange 
with  the  ions  of  water  which  dissociates  a  sufficient  percentage  of 
free  hydroxyl  ions  to  cause  a  strong  alkaline  reac'ion.  The  hydro- 
lysis is  in  accordance  with  this  equation: 

K-,  K-,  (C03)"     +     H20  K-,  (HO/     +      K',  (HCO3)'. 

Owing  to  its  caustic  action,  potassium  carbonate  is  not  given  inter- 
nally, but  in  dilute  solution  is  used  externally.  (See  Toxicology 
of  Potassium  Hydroxid,  p.  214). 

Potassium  Acid  Carbonate  or  Potassium  Bicarbonate  (KHCO3). 
— This  is  obtained  by  saturating  with  carbon  dioxid  a  solution  of 
the  normal  salt: 

K2C03     +      C02     +     H20  2KHC03. 

In  this  operation  the  carbonate  seems  to  take  up  another  molecule 
of  carbonic  acid,  H2CO3,  and  hence  the  name  bicarbonate.  On 
evaporation  it  crystallizes  in  rhombic  prisms,  much  less  soluble 


POTASSIUM  221 

than  the  carbonate,  and  almost  insoluble  in  alcohol.  The  dilute 
aqueous  solution  is  alkaline  in  taste  and  in  reaction,  in  spite  of 
the  unreplaced  hydrogen.  This  is  explained  by  the  hydrolysis 
converting  the  anion  (HCO3)'  into  undissociated  H2CO3,  and  set- 
ting free  a  few  ions  of  hydroxyl: 

KHC03     +     H20     =      K-,  (HO)'     +     H2CO3. 

Saleratus  is  a  name  given  to  the  bicarbonate  because  when 
heated  it  yields  CO2,  the  aerating  gas  of  "soda  biscuits": 


2KHCO3     =      K2CO3     +     H2O     +      CO 


If  not  used  with  other  chemicals  in  yeast  powders  the  residue  in 
the  bread  is  potassium  carbonate,  K2CO3,  unwholesome  because 
it  irritates  the  stomach. 

It  is  used  in  medicine  as  an  antacid  and  antilithic.  Dose:  20  to 
60  gr.  (1.3-4  gm.).  Owing  to  its  nauseous  taste  it  is  taken  in  an 
effervescent  draught. 

Potassium  citrate,  K3C6H5O7.H2O,  is  a  white,  granular  deli- 
quescent powder  having  a  cool  salty  taste;  it  is  soluble  in  an 
equal  weight  of  water,  and  slightly  soluble  in  alcohol.  The  solu- 
tion is  neutral  or  feebly  alkaline.  Dose:  10  to  30  gr.  (0.6-2  gm.). 

Liquor  potassii  citratis  is  a  palatable  preparation  in  which  the 
alkaline  taste  of  the  salt  is  overcome  by  the  more  agreeable  flavor 
of  citric  and  carbonic  acids.  It  is  prepared  by  dissolving  8  parts 
of  potassium  bicarbonate  in  50  of  water,  and  6  parts  of  citric  acid 
in  another  50  of  water  and  mixing  the  two  solutions.  It  is  a  feb- 
rifuge and  diuretic.  Dose:  i  to  i  fl.  oz.  (15-30  c.c.). 

Mistura  potassii  citratis  (neutral  mixture}  is  an  agreeable  prep- 
aration of  potassium  citrate  made  freshly  by  adding  to  100  parts 
of  fresh  lemon  juice  about  10  parts  of  potassium  bicarbonate  to 
neutralize  the  citric  acid  of  the  lemon  juice.  Dose:  same  as  for 
liquor  potassii  citratis.  The  neutral  potassium  salts  of  the  carbon 
acids,  citric,  acetic,  and  tartaric,  are  converted  into  alkaline  carbo- 
nates, either  in  the  blood  or  the  intestines,  and  when  eliminated 
by  the  urine  give  it  an  alkaline  reaction. 

Potassii  citras  effervescens  is  a  granular  solid,  containing 
20  per  cent,  of  potassium  citrate  mixed  with  enough  sodium 
bicarbonate  with  tartaric  and  citric  acids  to  react  when  dissolved 
with  disengagement  of  carbon  dioxid  and  forming  soluble  neutral 
salts. 

Potassium  acetate,  KC2H3O2,  is  prepared  by  neutralizing 
acetic  acid  with  potassium  carbonate  or  bicarbonate.  This  is  ob- 
tained as  white  crystals,  or  as  granular  powder,  very  deliquescent, 


222  THE    METALS 

and  having  a  saline  taste.  They  are  neutral  or  freely  alkaline  in 
reaction,  and  feebly  soluble  in  water  and  alcohol.  Dose:  5  to  60 
gr.  (0.3-4  gm.). 

Potassium  tartrate  (K2C4H4O6)  (neutral  tartrate  or  dipotassic 
tartrate),  is  made  by  neutralizing  the  bitartrate  with  potassium 
carbonate.  It  is  obtained  in  small  white  crystals  or  powder, 
deliquescent,  of  saline  taste,  freely  soluble  in  water,  giving  a  neu- 
tral reaction;  it  is  almost  insoluble  in  alcohol.  Dose:  J  to  4  dr. 
(2-16  gm.). 

Potassium  Bitartrate  (KHC4H4O6)  (Acid  Tartrate,  Cream 
oj  Tartar,  Monopotassium  Tartrate). — This  is  produced  in  the 
course  of  fermentation  of  grape  juice.  The  alcohol  precipitates 
impure  or  crude  tartar,  the  argol  of  commerce.  Dissolved  in 
boiling  water,  decolorized  and  washed  in  hydrochloric  acid,  it  is 
crystallized  by  evaporation  into  colorless  rhombs,  having  a  sour 
taste,  soluble  in  200  parts  of  water  and  15  of  boiling  water,  and 
almost  insoluble  in  alcohol.  Dose:  i  to  4  dr.  (4-16  gm.).  In 
ordinary  doses  diuretic  and  laxative;  in  excessive  doses  an  irri- 
tant poison,  causing  gastric  pain,  vomiting,  diarrhea,  and  collapse. 
There  is  no  specific  antidote;  emetics  followed  by  soothing  reme- 
dies are  always  called  for. 

Tests  for  Potassium  Salts.— The  detection  of  potassion  K', 
depends  upon  its  compounds  of  slight  solubility  formed  with 
the  anions  of  tartaric  acid  (HC4H4O6)/;  of  hydrochlorplatinic 
acid  (PtCl6)";  of  hydrofluosilicic  acid  (SiF6)";  of  perchloric  acid 
(C1O4)';  and  the  cobalt  nitrite  ion,  Co(NO2)6'". 

1.  To  a  concentrated  solution  of  a  neutral  potassium  salt  add 
a  fresh  strong  solution  of  tartaric  acid.     The  difficultly  soluble 
bitartrate  is  precipitated  white,  more  copiously  if  alcohol  be  added. 

2.  Acidulate  the  potassium  solution  with  a  few  drops  of  hy- 
drochloric acid  and  add  platinum  chlorid  and  alcohol.     Yellow 
crystals  of  potassioplatinic  chlorid  form: 

2KC1     +     H2PtCl6  K2PtCl6     +      2HC1. 

3.  With  potassium  salts   hydrofluosilicic   acid  slowly  forms   a 
translucent  gelatinous  precipitate,  soluble  in  strong  alkalies. 

4.  Perchloric    acid    yields    a    white    precipitate,    insoluble    in 
alcohol. 

5.  With  a  neutral  or  slightly  acid  potassium  solution,  sodium 
cobaltinitrite  gives  the  yellow  precipitate  of  potassium  cobaltini- 
trite:  (KNO2)6  Co(NO2)6  +  H2O. 

6.  The  readiest  test  is  the  lavender  or  reddish-violet  color  im- 
parted to  a  Bunsen  flame.     As  sodium  is  often  present  and  gives 
a  yellow  color,  which  masks  the  potassium  violet,  it  may  be  nee- 


SODIUM  223 

essary  to  eliminate  the  yellow  by  viewing  the  flame  through  cobalt- 
blue  glass.  This  permits  the  potassium  light  only  to  pass  through, 
appearing  reddish  in  color.  Viewed  by  the  spectroscope  the 
lavender  flame  is  resolved  into  a  dull-red  band  and  a  faint  violet 
line  (Fig.  19). 

SODIUM 
Symbol,  Na.     Atomic  weight,  23.05. 

Occurrence. — Like  the  other  alkaline  metals,  sodium  is  never 
found  free  in  nature.  If  liberated  and  not  protected,  its  activity 
causes  it  at  once  to  unite  with  other  elements.  Its  compounds, 
especially  sodium  chlorid,  are  very  abundant  and  very  soluble; 
hence,  they  are  washed  from  many  sources  in  large  amounts  by 
the  waters  flowing  into  the  sea  and  lakes  that  have  no  outlet. 
Solid  salt  beds  mark  the  place  where  salt  lakes  have  evaporated. 
The  vapors  rising  from  the  sea  are  borne  inland,  carrying  into  the 
air  minute  quantities  of  sodium  chlorid.  The  sensitive  spectro- 
scope shows  the  bright-yellow  sodium  line  in  almost  every  obser- 
vation, no  matter  what  substance  be  examined. 

Preparation. — At  one  time  the  metal  was  obtained  by  distil- 
lation of  the  carbonate  by  means  of  heated  carbon: 

Na2CO3     +        2C     =     Na2     +     3CO. 

But  the  most  economic  process  is  based  upon  the  principle  used 
by  Davy  when  he  first  liberated  it  from  the  hydroxid  by  electro- 
lysis. The  electric  current,  generated  by  water  power,  is  passed 
through  fused  sodium  hydroxid,  NaHO.  At  the  cathode  sodium 
and  free  hydrogen  appear,  the  sodium,  floating  upon  the  hydroxid, 
is  skimmed  off;  the  oxygen  escapes  at  the  anode. 

Properties. — Metallic  sodium  is  a  soft  plastic  solid, 'its  freshly 
cut  surface  shining  with  a  silvery  luster,  which  soon  tarnishes  in 
the  air.  To  protect  sodium  from  the  oxygen  of  the  air  it  is  kept 
under  petroleum,  but  a  more  volatile  hydrocarbon,  like  benzine, 
is  preferred,  as  it  is  more  easily  removed  from  the  surface  of  the 
metal.  Like  potassium  (though  it  is  less  violent)  it  has  an  ener- 
getic reaction  with  water: 

Na     +     H2O      =      NaHO      +     H. 

Thrown  upon  water,  its  movements  are  so  vivacious  as  to  dissi- 
pate its  heat  to  a  point  below  that  which  ignites  hydrogen.  If 
filter  paper  be  floated  on  the  water  and  a  small  piece  of  sodium 
placed  upon  it,  the  hot  globule  formed  cannot  move,  and  so 
enough  heat  is  retained  to  set  fire  to  the  evolved  hydrogen.  The 
sodium  gives  the  characteristic  yellow  color  to  the  hydrogen  flame, 


224  THE    METALS 

and  the  hydroxid  dissolves  in  the  water,  giving  it  alkaline  proper- 
ties, turning  litmus  blue  and  phenolphthalein  red  (Fig.  19). 

Sodium  Peroxid  (Na2O2).— When  sodium  is  heated  in  dry 
air  the  metal  falls  into  a  yellow  hygroscopic  powder.  This  is  an 
oxid  having  the  composition  Na2O2.  It  is  valuable  as  a  means  of 
preparing  hydrogen  dioxid  for  bleaching  textile  fabrics.  Water 
containing  it  is  alkaline  and  behaves  as  if  it  were  a  solution  of 
hydrogen  dioxid,  in  accordance  with  this  equation: 

Na202     +      2H20     =      2NaOH     +     H2O2. 

Sodium  Hydroxid  (NaOH)  (Sodium  Hydrate,  Caustic  Soda). 
— It  has  been  stated  above  that  when  water  acts  on  metallic 
sodium  the  hydroxid  is  produced.  From  the  carbonate  it  is 
obtained  by  the  action  of  lime-water,  the  calcium  being  precipi- 
tated as  carbonate,  the  sodium  hydroxid  being  left  in  solution: 

Na2CO3     +      Ca(OH)2     =      CaCO3     +      2NaOH. 

It  is  now  largely  manufactured  by  electrolysis  of  sodium  chlorid 
with  mercury  as  a  cathode  to  take  up  the  metal.  The  amalgam 
in  contact  with  water  forms  sodium  hydroxid. 

Properties. — The  hydroxid  occurs  in  gray-white  masses  or  in 
molded  sticks,  closely  resembling  potassium  hydroxid.  Like  that 
it  is  strongly  alkaline  in  reaction,  soapy  in  taste,  fuses  by  heat, 
dissolves  freely  in  water  with  evolution  of  heat,  is  deliquescent, 
and  in  the  moist  state  absorbs  carbon  dioxid  from  the  air,  forming 
the  carbonate.  This  carbonate  is  not  deliquescent,  .like  potassium 
carbonate,  but  efflorescent.  When  a  can  of  caustic  soda  is  opened, 
the  solid  first  liquefies,  then  absorbs  carbon  dioxid,  and  finally 
solidifies  in  a  whitish  powder. 

Under  the  name  of  " concentrated  lye,"  an  impure  mixture  of 
the  hydroxid  and  the  carbonate  is  largely  used  as  a  rapid  cleanser 
in  the  laundry  and  in  the  making  of  soap.  A  child,  in  playing 
about  the  laundry,  out  of  curiosity  eats  some  of  the  contents  of  a 
can  containing  "lye."  The  poison,  if  it  does  not  reach  the  stomach, 
corrodes  the  throat  and  leaves  a  stricture  of  the  gullet,  which  per- 
mits swallowing  of  liquid  food  only. 

Symptoms. — The  symptoms  are  those  of  a  corrosive  poison, 
differing  in  degree  only  from  those  caused  by  potassium  hydroxid. 

Fatal  Dose. — About  the  same  as  for  the  potassium  compounds. 

Fatal  Period. — The  duration  of  life  will  depend  on  the  dose  and 
the  lesions,  and  may  be  described  as  about  the  same  as  that  given 
for  the  potassium  compounds. 

Treatment. — The  antidotes  are  water  containing  vinegar  and 


SODIUM  225 

lemon  juice  to  neutralize  the  alkali,  and  milk,  oil,  or  butter  to 
saponify  it. 

Post-mortem  Appearances. — The  toxic  effect  is  purely  local. 
Although  less  active  than  the  potassium  compounds,  the  caustic 
forms  of  soda  dissolve  the  albumin  of  the  tissue,  abstract  the 
moisture,  saponify  the  fatty  material,  and  corrode  deeply  and 
widely. 

Detection. — The  history  of  the  case,  inspection  of  inflamed 
spots  on  the  face  and  hands,  the  strong  soapy  taste,  and  marked 
alkaline  reaction  of  vomited  matters  will  go  far  to  prove  a  caustic 
alkali.  The  tests  for  sodium  salts  (see  p.  229)  can  be  applied  to 
determine  the  character,  making  allowance  for  the  sodium  chlorid 
always  present  in  food  and  tissue.  As  commercial  sodium  hy- 
droxid  nearly  always  contains  a  small  quantity  of  arsenic,  a  trace 
of  the  latter  would  strengthen  the  evidence  in  favor  of  the  caustic 
alkali. 

Sodium  chlorid,  Nad,  common  or  table  salt,  is  a  type 
of  neutral  salts  in  general.  Present  everywhere  in  nature,  it  is 
essential  to  the  process  of  nutrition  in  living  things.  While 
potassium  is  found  in  the  blood-corpuscles,  sodium  salts  are 
constituents  of  the  plasma  and  other  animal  fluids.  Rock  salt 
is  a  mineral  deposited  at  the  bottom  of  salt  lakes  in  former  geo- 
logic eras.  As  obtained  from  the  salt  mines,  it  is  colored  by  a 
trace  of  iron  or  other  impurity. 

Properties. — From  salt  waters  it  separates  as  cubic  crystals 
enclosing  a  drop  of  the  salt  solution.  When  heated  the  drop 
passes  into  vapor,  bursting  the  crystal  with  a  crackling  noise.  It 
is  freely  soluble  alike  in  cold  or  hot  water,  insoluble  in  absolute 
alcohol. 

Normal  salt  solution  is  a  solution  of  sodium  chlorid  (0.7  to  0.9 
per  cent.).  It  is  made  by  dissolving  45  or  50  gr.  of  common  salt 
in  i  pt.  of  water  previously  sterilized  by  boiling.  This  is  injected 
warm  beneath  the  skin  of  the  buttocks  in  cases  of  loss  of  blood 
or  blood-poisoning;  it  has  about  the  same  osmotic  pressure  as 
the  blood. 

On  account  of  its  cheapness  sodium  chlorid  is  the  starting- 
point  for  obtaining  sodium  and  its  compounds,  as  potassium 
chlorid  is,  directly  or  indirectly,  for  that  metal. 

Sodium  bromid,  NaBr,  can  be  formed  by  saturating  a  solu- 
tion of  the  hydroxid  with  bromin  and  fusion  with  charcoal. 

Sodium  iodid,  Nal,  is  prepared  by  a  reaction  like  that  used 
for  potassium  iodid.  Essentially  stated,  ferrous  iodid  is  acted  upon 
by  sodium  hydroxid,  leaving  potassium  iodid  in  solution  and 
precipitating  ferrous  hydrate. 

The  bromid  and  iodid  resemble  the  chlorid  in  crystallizing  in 
15 


226  THE    METALS 

anhydrous  cubes,  but  they  are  more  soluble  in  water  than  is  the 
chlorid.  They  are  also  soluble  in  alcohol.  Dose:  5  to  60  gr. 

(0.3-3-5  gm-)-t 

Sodium    Nitrate   (NaNO3). — This    corresponds  to  potassium 

nitrate,  hence  is  called  Chili  niter,  or  saltpeter.  It  is  found  in  a 
rainless  district  of  Chili  as  solid  deposits  of  colorless  deliquescent 
crystals.  It  has  a  cool,  bitter,  saline  taste  with  neutral  reaction 
and  is  very  soluble  in  water,  but  not  in  cold  alcohol.  It  is  the 
most  important  manure  for  cultivated  plants.  In  dilute  solution 
in  the  soil  it  is  a  valuable  source  of  nitrogen  for  their  nutrition. 
Dose:  8  to  40  gr.  (0.5-2.5  gm.). 

Sodium  Sulphate  (Na2SO4,  ioH2O)  (Glauber's  Salt).— This 
occurs  dissolved  in  many  saline  aperient  waters.  In  the  manu- 
facture of  nitric  acid  it  is  left  in  the  retort: 

2NaNO3     +      H2SO4     =      2HNO3     +     Na2SO4. 

Indeed,  it  is  a  product  of  the  reaction  that  takes  place  on 
heating  sulphuric  acid  with  sodium  salts  of  volatile  acids  gener- 
ally; thus  in  making  hydrochloric  acid  from  common  salt: 

2NaCl   +     H2SO4    =      2HC1   +      Na2SO4. 

Properties. — It  forms  large,  colorless  prisms  which  effloresce 
in  air,  have  a  cool  saline  taste,  and  are  neutral  in  reaction,  very 
soluble  in  water,  and  insoluble  in  alcohol.  It  is  an  active  purga- 
tive in  the  dose  of  i  to  8  dr.  (4-32  gm.).  A  teaspoonful  in  a 
large  glass  of  water  makes  the  intestinal  contents  thin  and  watery. 
The  salt  is  not  absorbed,  so  the  osmotic  pressure  is  high  toward 
the  intestines  until  their  contents  are  of  equal  concentration  with 
the  body  fluids. 

The  solution  of  sodium  sulphate  stands  for  but  two  ions: 
sodion  Na*  and  sulphanion  (SO4)",  which  are  present  in  great 
abundance.  That  the  chemical  activities  are  not  due  to  sodium 
and  anhydrous  sulphuric  acid  is  shown  by  the  following  facts: 
We  have  learned  that  it  is  difficult  to  keep  the  metal  from  passing 
into  the  condition  of  sodion.  Notwithstanding  this  tendency, 
when  sodium  is  absolutely  dry  it  can  be  immersed  in  perfectly 
anhydrous  sulphuric  acid  without  any  chemical  change.  This 
inertness  disappears  instantly  on  adding  the  least  amount  of 
water.  The  metal  changes  to  the  ion  in  the  hydroxid  Na*(HO)'. 
The  water  also  gives  hydrion  H*  to  the  sulphuric  acid.  Dissocia- 
tion produces  sodion  Na*  and  sulphanion  (SO4)",  the  hydrion  H* 
and  hydroxidion  (HO)'  uniting  and  forming  water  which  does  not 
dissociate. 

2Na-,  (HO)' -  +    H*,H*,  (SO4)"    =    Na',  Na',  (SO4)"    4-    2H2O. 


SODIUM  227 

Sodium  bisulphate  (HNaSOJ  (sodium  acid  sulphate)  occurs 
in  long  four-sided  crystals  which  decompose  spontaneously  into 
H2SO4  and  Na2SO4. 

Sodium  Phosphates.— The  theoretic  relations  of  the  three 
phosphates  have  been  discussed  under  the  head  of  Phosphoric 
Acid  (p.  188).  It  remains  to  consider  them  practically. 

Sodium  Normal  Phosphate  (Na3PO4,  i2H2O)  (Trisodium 
Phosphate,  Basic  Phosphate). — When  sodium  hydroxid  is  added 
to  disodium  phosphate,  another  atom  of  sodium  is  taken,  forming 
a  salt  which  crystallizes  in  six-sided  prisms.  It  is  freely  soluble 
in  water,  with  an  alkaline  reaction,  absorbing  water  and  carbon 
dioxid  from  the  air  to  form  Na2CO3  and  reverting  to  the  more 
stable  salt,  HNa2PO4. 

Sodium  Neutral  Phosphate  (HNa2PO4,  i2H2O)  (Sodium 
Orthophosphate,  Disodium  Phosphate). — This  is  prepared  by  the 
reaction  between  monocalcium  phosphate  and  sodium  carbonate: 

Ca(PO4H2)2  +  2Na2CO3  =  CaCO3  +  2HNa2PO4  +  H2O  +  CO2. 

It  crystallizes  in  beautiful  rhombic  prisms  which  effloresce, 
losing  5H2O,  hence  it  should  be  kept  in  well-stoppered  bottles. 
It  is  very  soluble  in  water,  with  a  feeble  alkaline  reaction  to  lit- 
mus, but  not  to  phenolphthalein  (see  p.  130).  When  a  solution 
of  the  salt  is  saturated  with  carbon  dioxid  the  liquid  colors  blue 
litmus  red  and  red  litmus  blue,  and  it  is  said  to  have  an  ampho- 
teric  reaction.  Human  milk  and  urine  show  this  reaction  not 
infrequently.  It  is  present  in  the  blood  and  other  animal  fluids. 
Under  the  name  sodii  phosphas  (U.  S.  P.)  it  is  used  in  medicine 
as  a  laxative  and  biliary  stimulant.  Dose:  i  to  8  dr.  (4-32  gm.). 
Its  incompatibles  are  lead  acetate,  carbolic  acid,  chloral  hydrate, 
antipyrin,  alkaloids,  salicylic  acid,  and  sodium  salicylate. 

Liquor  sodii  phosphatis  compositus  is  a  concentrated  solution 
of  HNa2PO4  with  sodium  nitrate  and  citric  acid.  Each  cubic 
centimeter  contains  i  gm.  of  the  phosphate.  Dose:  i  to  2  f.  dr. 
(2-8  c.c.). 

Sodium  acid  phosphate  (H2NaPO4)  (monosodium  phos- 
phate) is  formed  by  treating  disodium  phosphate  with  phosphoric 
acid: 

Na2HPO4     +     H3PO4     =      2NaH2PO4. 

It  crystallizes  in  two  forms  and  dissolves  in  water,  forming  an 
acid  solution.  It  is  present  in  the  urine,  imparting  to  that  fluid 
an  acid  reaction  (see  p.  584). 

Sodium  Carbonate  (Na2CO3,  ioH2O)  (Normal  Carbonate, 
Disodium  Carbonate). — Under  the  name  of  sal  soda  or  washing 
soda  this  is  used  as  a  domestic  article  to  soften  water  and  assist 


228  THE    METALS 

in  cleansing.  It  occurs  in  rhombic  octahedrons  or  in  large  angular 
masses  which  effloresce  and  crumble  to  powder.  It  is  alkaline, 
acrid  in  taste,  soluble  and  caustic,  in  every  respect  like  the  cor- 
responding salt  of  potassium  only  less  severe. 

Of  the  several  methods  of  manufacture  the  Solvay  ammonia 
process  is  the  most  economic.  The  reaction  is  between  sodium 
chlorid  and  ammonium  bicarbonate,  the  products  being  ammonium 
chlorid,  which  remains  dissolved,  and  sodium  bicarbonate,  which 
is  only  sparingly  soluble  and  therefore  separates: 

NH4HC03     +     Nad  NH4C1     +     HNaCO3. 

The  bicarbonate,  HNaCO3,  when  collected,  dried,  and  heated, 
yields  the  carbonate,  water,  and  carbon  dioxid: 

2HNaCO3     =      Na2CO3     +      H2O      +      CO2. 

The  cryolite  process  is  to  heat  that  mineral,  a  double  sodium 
and  aluminium  fluorid,  with  limestone: 

Al2Na6F12     +     6CaCO3     =     6CaF2     +     Na8Al2O6     +     6CO2. 

Cryolite.  Limestone.  Calcium  fluorid.        Sodium  aluminate. 

The  sodium  aluminate  is  dissolved  out  with  water  and  treated 
with  the  CO2  given  off  in  the  first  stage: 

Na6Al206     +     3H20     +     3C02  3Na2CO3    +    2A1(OH)3 

Sodium  aluminate.  Sodium  carbonate.       Aluminium  hydrate. 

When  the  crystals  of  carbonate  effloresce  and  are  then  dried  at 
45°  C.  to  half  their  weight  they  form  the  white  powder,  so dii  car- 
bonas  monohydratus  (U.  S.  P.),  Na2CO3H2O. 

Sodium  carbonate  is  a  caustic  alkali  and,  hence,  is  not  given 
internally,  unless  in  small  doses  of  5  to  10  gr.  (0.32-0.65  gm.) 
largely  diluted.  The  antidotes  for  it  are  the  diluted  acids,  vinegar, 
lemon  juice,  and  the  oils  with  milk. 

Sodium  bicarbonate  (NaHCO3)  (acid  carbonate,  monoso- 
dium  carbonate)  occurs  in  Vichy  and  many  other  alkaline  mineral 
waters.  It  can  be  made  by  the  Solvay  ammonia  process  given 
above,  or  by  the  action  of  carbon  dioxid  on  the  normal  carbonate. 
Its  crystals  are  without  water  and  are  permanent  in  the  air.  It  is 
soluble  in  water,  imparting  a  saline  taste  and  an  alkaline  reaction. 
As  carbonic  acid  is  a  very  weak  acid  and  its  salts  are  hydrolyzed 
in  solution,  all  soluble  carbonates  dissociate  enough  hydroxyl  to 
give  an  alkaline  reaction,  the  carbonic  acid  remaining  almost 
undissociated: 

Na2CO3     +      H2O  Na',  (HCO3)'     +      Na',  (HO)'. 

NaHCO3  +     H2O      =      Na-,  (OH)'         +      H2CO3. 


SODIUM  229 

If  the  monosodium  carbonate  is  put  in  water  and  boiled,  it  loses 
CO2  and  dissolves  as  the  disodium  carbonate.  If  this  is  evapo- 
rated rapidly  a  salt  separates,  called  the  sesquicarbonate, 
Na4H2(CO3)3,  sometimes  written  Na2CO3,  NaHCO3,  2H2O. 

Sodium  bicarbonate  is  commonly  called  bread  soda  or  cooking 
soda,  to  distinguish  it  from  the  other  domestic  salt,  washing  soda, 
from  which  it  differs  in  the  mildness  of  its  local  effects,  being  with- 
out caustic  action.  It  is  given  internally  in  doses  of  10  to  40  gr. 
(0.6-3  gm.)  as  an  antacid. 

As  it  is  harmless  internally  and  is  a  convenient  source  of  carbon 
dioxid  gas,  it  is  extensively  used  as  a  substitute  for  yeast  in  "baking 
powders"  to  " aerate"  or  " raise"  bread.  One  kind  of  baking 
powder  widely  used  is  made  by  mixing  a  pound  of  potassium 
bitartrate  with  half  a  pound  of  sodium  bicarbonate.  A  sufficient 
quantity  is  mixed  with  the  dough,  and  in  the  process  of  baking 
the  acid  in  the  tartrate  is  neutralized  by  the  sodium,  and  the  gas 
CO2,  liberated  in  bubbles,  disseminated  through  the  bread,  making 
it  light  and  permeable  by  the  digestive  fluids.  The  equation  is: 

NaHCO3   +   HKC4H4O6   =   NaKC4H4O6  +  H2O   +    CO2. 

Sodium  Cream  of  Sodium-potassium 

bicarbonate.  tartar.  tartrate. 

Another  kind  of  baking  powder  which  is  considered  hurtful 
because  of  the  aluminium  it  contains  is  made  by  mixing  common 
alum,  or  aluminium  sulphate,  with  the  sodium  bicarbonate: 

6NaHC03   +   A12(S04)3   =    3Na2SO4   +    2A1(HO)3    +  6CO2. 

Sodium  Aluminium  Sodium  Aluminium 

oicarbonate.  sulphate.  sulphate.  hydrate. 

Sodium=potassium  tartrate  (NaKC4H4O6,  4H2O)  (potassii 
et  sodii  tartras,  U.  S.  P.),  Rochelle  salt  may  be  obtained  in  color- 
less crystals,  though  usually  it  is  a  white  powder,  of  a  bitter,  saline 
taste,  neutral  in  reaction,  freely  soluble  in  water.  It  is  a  mild 
laxative  in  doses  of  4  to  8  dr.  (8-32  gm.). 

Pulvis  Effervescens  Compositus  (U.  S.  P.)  (Seidlitz  Powder). 
—This  is  a  preparation  for  administering  Rochelle  salt  in  an  effer- 
vescing draught  to  conceal  the  bitter  taste.  One  powder  is  in  two 
papers,  the  blue  and  the  white.  The  blue  paper  contains  Rochelle 
salt,  2  dr.,  and  sodium  bicarbonate,  40  gr.;  the  white  paper  con- 
tains tartaric  acid,  35  gr.  If  dissolved  separately  and  the  two 
solutions  mixed  there  is  brisk  effervescence,  due  to  the  escape  of 
the  CO2.  One  or  two  of  them  may  be  taken  while  effervescing. 

Tests  for  Sodium. — (i)  The  most  sensitive  and  readiest 
means  of  recognizing  sodium  is  the  bright-yellow  color  it  imparts 
to  the  colorless  flame  of  a  Bunsen  burner.  The  spectroscope 
places  the  sodium  flame  as  an  intense  line  in  the  pure  yellow,  cor- 


230  THE    METALS 

responding  to  D  in  the  solar  spectrum.  As  all  bright  flames 
under  ordinary  circumstances  show  this  D  line,  it  is  inferred  that 
a  trace  of  sodium  is  almost  universal.  Continued  heat  soon  vol- 
atilizes this  accidental  trace  of  sodium  on  platinum  wire.  When 
the  amount  is  appreciable  by  weight,  say  as  much  as  i  mg.,  the 
bright-yellow  color  lasts  so  much  longer  that  the  experienced 
analyst  easily  distinguishes  it  from  the  accidental  trace  (Fig.  19). 

(2)  The  salts  of  sodium  are  all  white  and  are  non-volatile  to 
red  heat.  As  they  are  all  soluble  in  water,  no  ordinary  reagent 
precipitates  them.  With  the  anions  of  hydro fluosilici.c  acid  (SiF6)", 
and  pyroantimonic  acid  (Sb2O7)",  it  forms  compounds  of  low 
solubility. 

LITHIUM 

Symbol,  Li.     Atomic  weight,  7. 

This  metal  occurs  in  combination  in  mineral  waters  and  as  a 
silicate  in  lepidolite. 

Properties. — Lithium  resembles  sodium  in  many  respects, 
being  silver  white  and  ductile.  With  a  specific  gravity  of  0.59  it 
is  the  lightest  metal.  It  floats  upon  water,  decomposing  it,  but 
not  igniting  the  hydrogen.  It  burns  at  200°  C.  (392°  F.)  with  a 
crimson  flame.  Its  compounds  do  not  differ  much  from  those  of 
sodium.  Its  hydroxid  reacts  strongly  alkaline.  The  salts  used 
in  medicine  are  the  bromid,  citrate,  and  carbonate. 

Lithium  bromid,  LiBr,  is  obtained  by  saturating  with  lith- 
ium carbonate  a  solution  of  hydrobromic  acid.  It  forms  crystal- 
line needles  that  are  very  deliquescent  and  soluble  in  water  and 
alcohol.  Dose:  5  to  20  gr.  (0.32-1.3  gm.).  Its  incompatibles 
are  the  acids;  the  salt  of  antimony,  bismuth,  silver,  lead,  mer- 
cury, copper;  and  the  alkaloids. 

Lithium  carbonate,  Li2CO3,  is  a  white  alkaline  powder,  only 
sparingly  soluble  in  water,  but  more  soluble  in  carbonated  water, 
which  converts  it  into  the  bicarbonate.  Dose:  5  to  15  gr.  (0.32-1 
gm.). 

Lithium  citrate,  made  by  the  action  of  citric  acid  on  the 
carbonate,  is  much  more  soluble  than  the  carbonate.  Dose:  5 
to  15  gr.  (0.32-1  gm.). 

Lithii  citras  effervescens  is  a  granular  solid,  containing  5.0  per 
cent,  of  the  citrate  mixed  with  enough  sodium  bicarbonate  with 
tartaric  and  citric  acids  to  react  when  dissolved,  liberating  carbon 
dioxid  and  forming  neutral  salts. 

Lithium  urate  is  the  compound  made  by  the  metal  with 
uric  acid  of  the  body.  It  is  more  soluble  than  the  natural  urates, 
and  hence  lithium  salts  are  given  to  dissolve  urate  deposits  in  the 
joints. 


AMMONIUM  23 1 

Tests  for  Lithium.— (i)  Lithium  is  identified  by  the  red 
color  of  its  flame.  The  spectroscope  shows  two  bright  lines,  one 
red  and  the  other  yellow,  distinct  from  the  sodium  line  (Fig.  19). 

(2)  Concentrated  solutions  are  precipitated  by  ammonium  car- 
bonate as  white  lithium  carbonate. 

RUBIDIUM 

Symbol,  Rb.     Atomic  weight,  85.4. 

Although  wi.dely  distributed  in  nature,  the  quantity  of  rubidium 
obtainable  by  convenient  processes  is  very  small.  It  gets  its  name 
from  the  two  dark-red  lines  of  its  spectrum  (Fig.  19).  The  metal 
and  its  compounds  resemble  potassium  and  its  compounds  very 
closely — physically,  chemically,  and  medically.  Its  presence  is 
doubtful  if  it  cannot  be  identified  by  the  color  of  its  flame.  It  is 
separated  from  potassium  by  the  fact  that  the  double  salt  with 
platinum  chlorid  is  a  little  less  soluble  than  the  corresponding 
potassium  salt. 

CESIUM 
Symbol,  Cs.     Atomic  weight,  133. 

This  is  an  extremely  rare  metal,  discovered  by  the  two  sky- 
blue  lines  of  its  spectrum  (Fig.  19).  It  resembles  rubidium  and 
potassium,  with  more  chemical  energy  than  either,  being  the 
strongest  base-former  of  all  the  elements. 

AMMONIUM 
Formula,  NH4.     Molecular  weight,  18. 

A  class  of  compounds  closely  resembling,  physically  and 
chemically,  those  of  potassium  has  been  found  to  contain  the 
group  NH4.  When  solutions  of  these  salts  are  electrolyzed,  the 
cation  is  (NH4)*,  and  if  mercury  be  used  as  a  cathode,  an  amalgam 
is  formed  like  that  of  potassium.  Although  the  group  has  never 
been  isolated  as  a  metal,  the  ion  is  so  much  like  the  univalent 
cations  of  alkali  salts  that  it  is  considered  to  belong  to  the  same 
family  with  the  alkali  metals. 

Ammonia  (NH3)  (Volatile  Alkali).— This  occurs  in  nature  in 
small  amounts  widely  distributed.  A  trace  is  present  in  the  air 
and  in  surface  waters  that  have  been  contaminated  by  nitrogenous 
waste.  It  is  evolved  from  stable  manure,  and  in  the  soil  is  most 
important  as  a  source  of  nitrogen  for  the  growth  of  plants. 

Preparation. — Ammonia  can  be  formed  by  direct  union  of 
hydrogen  and  nitrogen  with  the  aid  of  the  electric  spark,  by  putre- 
faction or  destructive  distillation  of  proteid  substances,  and  by 
heating  ammonium  hydroxid:  NH4HO  =  NH3  +  H2O.  The  most 


232 


THE    METALS 


convenient   method  is  to  heat  an  ammonium  salt   with  a  strong 
base,  such  as  an  alkaline  hydroxid  or  lime: 

2NH4C1      +      Ca(HO)2     =      CaCl2      +      2H2O 

Calcium  hydroxid. 


Ammonium  chlorid. 


Calcium  chlorid. 


2NH3 

Ammonia. 


Properties. — Ammonia,  NH3,  is  a  colorless  gas  having  a 
pungent  odor,  irritating  to  the  eyes  and  the  mucous  lining  of  the 
air-passages,  and  turning  moist  red  litmus-paper  blue.  Under  a 
pressure  of  6J  atmospheres  at  10°  C.  (50°  F.)  it  is  condensed 
to  the  liquid  used  in  ice-machines  to  create  a  freezing  temperature 
by  its  evaporation.  Ammonium  hydroxid  is  a  strong  solution  of 
the  gas  in  water.  Water  will  absorb  700  times  its  volume  at 
ordinary  temperatures  and  thereby  acquire  the  alkalinity,  the 
pungency,  and  the  chemical  properties  of  the  gas  itself  (Fig.  60). 
This  is  regarded  as  an  act  of  chemical  union  in  which  the  anhydrid 
NH3,  unites  with  H2O  to  form  the  hydroxid  NH4HO. 

The  liquefied  ammonia  gas,  NH3,  is  used  in  ice-factories  and 
refrigerators.  Occasionally  the  receivers  burst  and  the  vapors  fill 
the  room,  with  deadly  consequences  to  those  who  are  exposed  to 
them.  To  arouse  fainting  persons  it  is  sometimes  given  too 
strong  by  inhalation. 

Ammonium  Hydroxid  (NH4HO)  (Ammonia  Water).— When 
ammonia  is  dissolved  in  water  a  compound  is  formed  which 
neutralizes  acids  and  forms  salts;  hence,  it  is  basic.  As  the 
basicity  is  due  to  hydroxidion  the  dissociation  of  ammonium 
hydroxid  is  represented  by  the  equation — 

NH4OH  (NH4)',  (OH)'. 

The  smell  of  the  solution  shows  that  some  portion  of  the  am- 
monia is  still  in  the  condition  of  the  uncombined  gas.  The  amount 

of  hydroxyl  dissociated  is  not  so 
great  as  with  potassium  hydroxid 
or  sodium  hydroxid,  as  is  shown 
by  the  lower  electric  conductivity. 
In  spite  of  the  irritant  action  on  the 
mucous  membranes  and  the  strong 
impression  made  on  the  olfactory 
nerves,  ammonium  hydroxid  is  not 
a  strong  base.  Still,  it  readily  forms 
salts  with  all  acids. 

Under  the  names  of  hartshorn 
and  ammonia,  ammonium  hydroxid 
is  largely  used  in  the  household  as  a 

FIG.  6o.-Charging  water  with  soluble  gas.       cleansing     agent     to     remove     paint, 

oil,    and  dirt    generally   from   clothing;    hence    it  is  easy  to  have 
accidental  poisoning  with  it. 


AMMONIUM  233 

Pharmaceutic  Preparations. — Aqua  ammonia  jortior  (U.  S.  P.) 
contains  28  per  cent,  by  weight  of  ammonia  gas,  has  a  specific 
gravity  of  0.897,  an<^  *s  a  powerful  corrosive.  It  is  incompatible 
with  acids,  alkaloids,  chlorin  water,  iodin,  bromin,  and  most 
metallic  salts.  Aqua  ammonia  (U.  S.  P.)  has  i  J  times  more  water, 
only  10  per  cent,  of  ammonia  gas,  and  a  specific  gravity  of  0.958. 
Dose:  10  to  30  1TL  (0.60-1.90  c.c.).  Spiritus  ammonia  (U.  S.  P.)  is 
a  solution  of  the  gas  in  alcohol,  of  the  same  strength  as  the  aqua, 
and  better  adapted  for  internal  use.  When  it  has  added  to  it  the 
carbonate,  with  small  quantities  of  oils  of  nutmeg,  lemon,  and 
lavender,  the  aromatic  spirits  is  produced.  Dose:  i  to  2  fl.  dr. 
(3.75-7.50  c.c.).  Ammonii  carbonas  occurs  as  whitish  angular 
masses,  giving  off  the  characteristic  irritating  and  alkaline  vapor 
of  ammonia,  and  caustic  in  strong  solution  (p.  235). 

Symptoms. — The  nature  and  gravity  of  the  effects  will  depend 
greatly  on  concentration  of  the  solution,  and  on  whether  or  not 
the  subject  received  a  large  dose  of  the  vapor  by  the  lungs.  The 
direct  chemical  action  upon  vital  tissue  is  the  same  as  that  of 
potassium  hydroxid,  though  less  in  degree — that  is,  the  albumin 
is  dissolved,  the  fatty  matter  saponified,  and  the  water  abstracted. 
The  respiratory  symptoms  are  a  suffocative  feeling  due  to  spasm 
of  the  glottis,  followed  by  a  sense  of  pain  and  weight  in  the  chest, 
with  an  irritative  cough  due  to  inflammation  of  the  larynx  and 
trachea. 

The  symptom  due  to  the  local  caustic  effect  of  the  fluid  is 
burning  pain  in  the  mouth  and  throat,  extending  to  the  stomach  if 
the  poison  went  so  far.  There  are  salivation,  vomiting,  and  diffi- 
culty in  swallowing.  As  a  result  of  a  free  absorption  of  the  poi- 
son by  the  lungs  and  stomach,  cases  display  grave  remote  effects 
sometimes  with  great  rapidity.  The  heart's  action  is  sometimes 
arrested  in  a  few  minutes;  sometimes  there  is  immediate  uncon- 
sciousness with  coma,  and  death  in  a  few  minutes;  sometimes 
there  is  unconscious  delirium,  soon  ending  in  death. 

Fatal  Dose. — A  teaspoonful  of  the  stronger  aqua  ammoniae 
has  in  at  least  one  instance  proved  fatal,  and  two  fluidrams  have 
caused  death  in  two  or  three  other  cases.  Recovery,  however, 
has  sometimes  followed  much  larger  doses,  such  as  a  tablespoon- 
ful,  and  even  upward  of  a  fluidounce  has  been  taken  without 
fatal  results. 

Fatal  Period. — By  suffocation  and  syncope  death  has  occurred 
in  four  minutes  after  inhalation  of  the  gas.  On  the  other  hand, 
death  may  occur  after  many  months  as  a  result  of  the  starvation 
due  to  stricture  of  the  gullet  or  pylorus. 

Treatment. — The  antidotes  are  weak  vinegar,  lemon  juice, 
oil,  butter,  and  milk.  The  sequels  are  to  be  treated  as  they  arise. 


234  THE    METALS 

Postmortem  Appearances. — These  are  not  markedly  different 
from  the  inflamed  state  of  the  alimentary  tract  as  caused  by  the 
other  caustic  alkalis.  When  the  vapor  acts  as  an  irritant  upon 
the  air-passages,  an  inflamed  state  of  the  larynx  and  even  of  the 
bronchi  may  be  found. 

Ammonium  chlorid  (NH4C1)  (sal  ammoniac)  is  produced  from 
the  ammonia  liquor  of  gas  works  by  neutralizing  with  hydrochloric 
acid  and  evaporating.  Although  it  forms  a  white  crystal  of  the 
regular  system  it  is  usually  found  in  tough  fibrous  masses,  salty  in 
taste,  without  odor  and  freely  soluble.  At  450°  C.  (862°  F.)  it 
passes  into  colorless  vapors,  which,  if  water  be  present,  are  a 
mixture  of  NH3  and  HC1.  Although  a  neutral  salt,  the  aqueous 
solution  is  feebly  acid,  owing  to  the  slight  hydrolysis  to  be  expected 
with  a  salt  of  a  weak  base.  Some  ammonion  unites  with  the 
hydroxidion  of  the  water  to  form  NH4OH: 

NH4C1     +      H20     =      NH4OH     +     H',  Cl'. 

The  weak  ammonium  hydroxid  is  dissociated  to  a  much  lower 
degree  than  is  the  strong  acid  hydrochloric.  The  excess  of  hy- 
drion  causes  the  acid  reaction.  If  the  solution  be  boiled,  a  por- 
tion of  ammonia  escapes  and  the  acid  reaction  increases. 

The  facility  with  which  it  splits  off  hydrogen  chlorid  makes  it 
useful  as  a  flux  to  clean  metallic  surfaces  for  soldering  and  as  an 
exciting  salt  in  the  Leclanche  battery  cell.  Dose:  5  to  20  gr. 
(0.32-1.29  gm.)  (p.  47). 

Ammonium  nitrate,  NH4NO3,  can  be  obtained  by  neutral- 
izing nitric  acid  with  ammonium  hydroxid.  The  solution  evap- 
orated yields  long  flexible  prisms.  Heated  to  150°  C.  (302 °F.), 
the  dry  salt  fuses,  and  at  210°  C.  (410°  F.  )  decomposes  into  nitrous 
oxid  and  water: 

NH4N03     =     N20      +      2H20. 

When  quickly  heated  to  a  high  temperature,  it  yields  a  large 
volume  of  mixed  gases — ammonia,  nitric,  and  nitrous  oxids; 
hence,  is  used  as  an  explosive. 

Ammonium  acetate,  NH4C2H3O2,  is  official  in  aqueous  solution 
as  liquor  ammonii  acetatis  (U.  S.  P.)  (spirit  of  mindererus),  an  anti- 
pyretic in  doses  of  2  to  8  f.  dr.  (7.4-30  c.c.).  This  is  a  7  per  cent, 
solution  of  a  salt  made  by  saturating  dilute  acetic  acid  with  ammo- 
nium carbonate. 

Ammonium  carbonate  [(NH4)2CO3,H2O]  (normal  carbonate, 
diammonium  carbonate)  is  formed  as  a  white  crystalline  solid 
and  is  not  stable.  In  air  it  breaks  down  rapidly  into  ammonia 
and  a  white  powder  of  the  acid  carbonate: 

(NH4)2C03     =     NH3     +     NH4HC03. 


AMMONIUM  235 

Ammonium  bicarbonate  (NH4HCO3)  (acid  carbonate,  monoam- 
monium  carbonate)  is  prepared  by  saturating  ammonia  water 
with  carbon  dioxid.  It  crystallizes  in  large  rhombic  prisms, 
stable,  and  freely  soluble  in  water.  Heated  to  60°  C.  (140°  F.) 
it  breaks  up  into  NH3  +  H2O  +  CO2. 

Ammonium  sesquicarbonate  (ammonii  carbonas,  U.  S.  P., 
sal  volatile,  Preston  salts)  is  a  combination  of  the  acid  carbonate 
described  above:  NH4HCO3  with  a  variable  amount  of  salt  of 
carbamic  acid,  called  ammonium  carbamate,  NH4CO2NH2,  which 
appears  to  be  the  carbonate  deprived  of  water: 

(NH4)2C03  H20      =     NH4C02NH2. 

The  combined  salts  crystallize  in  hard  translucent  rhombic 
prisms  with  a  pungent  odor  and  an  alkaline  reaction.  When  this 
changes  to  the  acid  carbonate  it  may  be  used,  in  whole  or  in  part, 
in  place  of  sodium  bicarbonate  in  baking  powders.  When  used 
alone  to  aerate  pastry,  by  the  heat  of  the  oven,  it  is  all  converted 
to  H2O  and  the  gases  NH3  and  CO2.  Dose:  5  to  20  gr.  (0.32- 
1.29  gm.).  Its  incompatibles  are  the  acids,  acid  salts,  alum, 
alkaloids,  and  most  metallic  salts. 

Ammonium  Sulphid  (NH4)2S.—  By  saturating  strong  ammo- 
nium hydroxid  with  hydrogen  sulphid  in  excess  there  is  formed 
in  solution  ammonium  hydrosulphid,  NH4HS.  To  obtain  ammo- 
nium sulphid,  an  equal  volume  of  ammonium  hydroxid  must  be 
added,  so  as  to  replace  the  second  hydrogen  atom.  The  solution 
containing  (NH4)2S  is  at  first  colorless,  with  a  disagreeable  odor, 
but  soon  turns  yellow  in  the  air  from  oxidation  and  separation 
of  sulphur,  part  of  which  dissolves,  forming  polysulphids,  and 
part  is  precipitated.  It  is  used  as  a  reagent  to  precipitate  the 
heavy  metals,  the  sulphids  of  which  are  soluble  in  free  acids.  It 
is  also  employed  in  organic  chemistry  as  a  reducing  agent.  The 
yellow  sulphid  is  used  to  dissolve  the  sulphids  of  arsenic,  anti- 
mony, and  tin  in  analytic  operations. 

Ammonium  Phosphates.— There  are  three  possible  phos- 
phates, but  the  normal  salt  is  too  unstable  to  keep.  The  mono 
and  diammonium  phosphates  exist,  but  are  insignificant. 

Ammonium=sodium  phosphate,  (HNaNH4PO4,  4H2O),  is 
called  microcosmic  salt  because  it  is  in  the  residue  of  evaporated 
stale  urine  of  man,  the  microcosm.  It  is  much  used  in  blowpipe 
work  to  make  a  colorless  bead  on  the  platinum  loop.  Metallic 
compounds  color  the  bead  in  characteristic  tints. 

Tests  for  Ammonium  Salts.— Ammonia  gas  turns  red  litmus- 
paper  blue,  and  makes  a  white  smoke  when  mixed  with  the  fumes 
of  a  rod  wet  with  hydrochloric  acid.  All  salts  are  volatile  when 
heated,  and  evolve  the  gas  spontaneously  or  when  heated  with 


236  THE    METALS 

calcium  hydroxid.  Platinum  chlorid  yields  a  yellow  precipitate 
like  that  given  by  potassium.  Not  only  does  ammonium  form 
salts,  like  those  of  potassium,  of  feeble  solubility  with  the  anion 
of  chlorplatinic  acid,  but  also  with  the  anion  of  tartaric  acid  and 
the  cobaltinitrite  ion  (p.  222). 

Detection  of  Ammonium  Salts. — Owing  to  the  volatility  of 
ammonia,  its  hydroxid  and  its  carbonate,  these  soon  escape  from 
the  body.  During  life  or  soon  after  death  detection  is  easy 
by  the  characteristic  odor.  If  the  volatile  preparation  has  been 
fixed  by  the  antidote,  the  vapor  can  be  developed  by  heating 
the  material  with  lime.  This  vapor  will  be  alkaline  and  form 
white  fumes  with  hydrochloric  acid. 

If  the  organic  material  to  be  examined  is  putrid,  allowance 
must  be  made  for  the  ammonia  produced  by  putrefaction.  This 
is  never  enough  to  develop  the  dense  white  fumes  of  ammonium 
chlorid  from  a  rod  wet  with  hydrochloric  acid.  The  amount 
may  be  estimated  by  distillation,  neutralizing  the  distillate  with 
hydrochloric  acid,  evaporating  nearly  to  dryness,  and  precipitating 
the  double  chlorid  of  ammonium  and  platinum  by  adding  excess 
of  alcoholic  solution  of  platinum  chlorid.  After  filtration  the 
precipitate  is  washed  with  alcohol,  dried,  and  weighed;  100  parts 
represent  8.6  parts  of  ammonia,  NH3. 

The  Energy  of  Alkali  Metals.— The  chemical  energy  of  all 
the  members  of  this  group  is  partly  expressed  in  the  statement 
that  their  ions  are  electropositive  and  univalent.  Univalent 
metals  carry  but  one  electric  charge,  and,  according  to  Faraday's 
law,  the  amounts  of  electricity  set  in  motion  are  the  same  for  each 
atom  of  an  alkali  metal.  In  the  passage  of  free  alkali  metals  to  the 
ion  state  they  take  up  equal  quantities  of  electricity,  as  their  capaci- 
ties are  equal.  Their  differences  of  energy  find  an  explanation  in 
the  other  factor,  the  potential  or  intensity  with  which  they  work. 
The  ions  of  potassium  with  a  higher  potential  are  discharged  under 
certain  conditions  with  greater  readiness  or  velocity  than  those  of 
sodium  and  ammonium. 


IL- METALS  OF  THE  ALKALINE  EARTHS 

The  alkaline  earths — lime,  CaO,  baryta,  BaO,  strontia,  SrO, 
and  magnesia,  MgO,  are  oxids  with  a  reaction  like  the  caustic 
alkalis,  though  they  are  much  less  soluble.  The  metals  form 
divalent  ions  exclusively,  are  heavier  than  water,  decompose  water 
slowly,  form  normal  carbonates  and  phosphates  insoluble  in  water, 
but  soluble  when  carbon  dioxid  is  in  solution,  and  form  hydroxids 
that  are  sparingly  soluble. 


CALCIUM  237 

CALCIUM 

Symbol,  Ca.     Atomic  weight,  40.1. 

Occurrence. — In  the  form  of  silicates  and  carbonates  this 
metal  is  very  abundant  and  widely  distributed  in  nature.  Marble 
is  the  carbonate  crystallized;  limestone  and  chalk,  the  same  salt 
less  pure.  It  is  also  present  in  the  shells  of  eggs  and  molluscs. 
Gypsum  is  the  sulphate.  The  bones  of  animals  are  rich  in  the 
phosphate. 

Preparation. — Calcium  is  separated  from  the  iodid  by  metallic 
sodium: 

CaI2     +      2Na  2NaI     +      Ca. 

When  pure  it  is  grayish-white,  like  polished  iron,  and  fairly  hard. 
Water  attacks  it  slowly,  and  it  unites  with  oxygen  when  heated. 

Calcium  oxid  (CaO)  (Calx,  Quicklime). — This  is  obtained 
by  heating  the  carbonate,  as  limestone  or  marble,  in  limekilns: 

CaCO3       — »      CO2         +         CaO. 

Carbonic  acid  is  so  weak  that  it  cannot  only  be  expelled  by  other 
acids,  but  even  driven  away  as  anhydrid  by  strong  heat. 

Lime  is  a  white,  amorphous,  almost  infusible,  powder.  Exposed 
to  the  air  it  becomes  air-slaked — that  is,  it  absorbs  moisture,  forming 
hydroxid: 

CaO  +  H20  Ca(OH)2. 

At  the  same  time  the  calcium  hydroxid  takes  carbon  dioxid  to 
form  calcium  carbonate,  so  that  it  soon  becomes  chemically  inert. 

Ca(OH)2          +          CO2  CaCO3          +          H2O. 

The  absorption  of  CO2  from  the  air  to  form  CaCO3  is  practically 
a  reversal  of  the  reaction  by  which  the  CO2  was  driven  off  in 
lime  burning.  If  that  operation  is  carried  on  in  a  closed  flask 
the  pressure  and  the  temperature  determine  the  result  just  as  they 
determine  whether  water  shall  remain  liquid  or  boil  off  in  vapor. 
At  ordinary  temperature  in  the  open  there  is  more  pressure  of 
CO2  in  the  atmosphere  than  the  decomposition  pressure  of  CaCO3; 
hence  the  reaction  is  reversed  and  CO2  is  absorbed. 

The  question  of  the  degree  of  dampness  in  a  room  may  be  set- 
tled by  closing  it  hermetically,  weighing  a  dish,  and  putting  on  it 
i  kg.  (2  Ib.)  of  quicklime,  and  exposing  it  for  twenty-four  hours. 
If  the  kilogram  gain  in  weight  i  gm.,  or  the  2  Ib.  Troy  gain  12  gr., 
then  the  room  is  too  damp  to  be  wholesome. 


238  THE    METALS 

When  lumps  of  quicklime  are  mixed  with  water,  the  water  is 
absorbed,  heat  is  evolved,  the  lime  swells  and  breaks  down  into  a 
white  powder,  which  if  added  to  more  water  remains  for  a  time 
mechanically  suspended  as  whitewash  or  milk  oj  lime.  Eventually 
this  settles  and  a  very  small  percentage  (0.14  per  cent,  or  1.4  gm. 
per  L. — less  than  i  gr.  to  i  f.  oz.)  is  left  dissolved  to  make  lime- 
water  or  liquor  calcis  (U.  S.  P.)-  Its  electric  conductivity  shows 
that  dissociation  is  almost  complete.  The  following  equation 
exhibits  a  relatively  large  amount  of  hydroxidion: 

Ca(OH)2     =      Ca",  (OH)',  (OH)'. 

These  hydroxyl  ions  give  it  an  alkaline  reaction  to  litmus  and 
confer  upon  it  strong  basic  properties.  Owing  to  its  feeble  sol- 
ubility there  is  very  little  concentration  of  these  ions;  hence, 
lime-water  is  used  in  the  laboratory  and  medicine  when  very 
limited  basic  or  antacid  effects  are  desired.  It  is  a  clear,  colorless, 
odorless  liquid  of  feeble  taste  and  sedative  action.  The  milk  oj 
lime  or  lime  paste  is  quite  irritating  to  the  stomach,  acting  like 
the  caustic  alkalis  and  sometimes  causing  dangerous  inflammation. 
The  antidotes  are  dilute  vinegar,  lemon  juice,  and  the  oils.  Lime- 
water  is  kept  standing  over  the  excess  of  lime,  so  that  it  renews 
its  strength  as  fast  as  the  surface  layers  take  up  carbon  dioxid 
from  the  air  to  be  precipitated  as  calcium  carbonate.  When  the 
gas  is  passed  through  lime-water,  this  salt  separates  and  imparts 
a  milky  appearance.  Mortar  and  plaster  are  mixtures  of  sand, 
slaked  lime,  and  water,  which  slowly  change  by  exposure  to  air 
to  a  hard  mass  of  calcium  carbonate  and  calcium  silicate.  In 
doing  so  they  liberate  water,  making  the  wall  damp  for  months 
together,  unless  the  process  be  hastened  by  open  coal  fires. 

Fresh  milk  of  lime  is  used  in  chamber  vessels  to  disinfect  urine, 
vomit,  and  feces.  As  whitewash,  it  disinfects  the  walls  of  cellars. 

Syrupus  Calcis  (U.  S.  P.)  (Syrup  oj  Lime,  Saccharated  Solution 
oj  Lime). — The  solubility  of  lime  is  much  increased  by  adding 
sugar.  The  amount  dissolved  is  7  or  8  gr.  to  i  fl.  oz.  when  5 
per  cent,  of  lime  and  30  of  sugar  are  boiled  in  100  of  water.  The 
dose,  as  an  antidote  to  oxalic  and  carbolic  acids,  is  from  J  to  2  dr. 
(1.95-7.80  gm.).  Lime-water  and  the  syrup  are  incompatible 
with  acids  and  metallic  salts  generally. 

Linimentum  calcis  (U.  S.  P.)  (carron  -oil)  contains  equal  parts 
of  lime-water  and  linseed  oil.  It  is  a  calcium  soap. 

Soda  lime  is  a  mixture  of  quicklime  and  sodium  hydroxid,  dried. 
It  is  used  in  the  laboratory  for  absorbing  carbon  dioxid  from 
mixed  gases. 

Calcium  chlorid  is  used  as  a  desiccating  agent  in  the  lab- 
oratory, in  the  form  of  a  dried  spongy  mass.  It  is  less  perfect  in 


CALCIUM  239 

this  respect  than  sulphuric  acid.  In  the  anhydrous  condition  it  is 
a  colorless  salt  of  great  solubility.  With  water  it  forms  five  dif- 
ferent hydrates.  The  hexahydrate,  CaCl2,  6H2O,  occurs  in  large 
deliquescent  crystals,  which  on  heating  lose  water,  becoming 
anhydrous.  Dose  as  an  antistrumous  alterative:  5  to  20  gr. 
(0.32-1.2  gm.). 

Calcium  Hypochlorite  (CaOCl2)  (Calx  Chlorinata,  U.  S.  P., 
Bleaching  Powder).  —  This  substance  has  been  fully  considered 
under  the  head  of  hypochlorous  acid  (see  p.  140).  It  does  not 
contain  calcium  chlorid  in  the  form  of  a  mechanical  mixture,  as  it 
does  not  deliquesce.  When  dissolved  in  water  it  dissociates  in  the 
same  way  as  it  would  if  there  were  calcium  chlorid  in  it,  though 

Cl 

its  composition  is  best  expressed  by  the  formula 


Ca",  Cl/     +      Ca",  (OC1)'2. 

Calx  Sulphurata  (U.  S.  P.)  Sulphurated  Lime.—Ry  heating 
together  a  mixture  of  calcium  sulphate,  starch,  and  charcoal,  a 
compound  is  obtained  which  is  misnamed  calcium  sulphid.  It 
contains  the  sulphid  CaS  and  also  the  sulphate  CaSO4  in  varying 
proportions,  not  less  than  55  per  cent,  of  CaS.  It  is  a  grayish- 
white  offensive  powder  with  an  alkaline  reaction,  slightly  soluble 
in  water,  and  used  internally  to  combat  suppuration.  Dose:  yV 
to  J  gr.  (0.006-0.032  gm.). 

Calcium  Carbid  (CaC2).  —  When  carbon  and  lime  are  heated 
to  the  high  temperature  of  an  electric  furnace  they  unite,  carbon 
monoxid  being  set  free: 

3C     +      CaO     =      CaC2     +      CO. 

While  calcium  carbid  can  be  obtained  pure  as  transparent  crys- 
tals, the  commercial  product  comes  in  grayish-brown  hard  lumps, 
with  the  odor  of  garlic  or  phosphureted  hydrogen.  Its  value  is 
due  to  the  fact  that  it  is  decomposed  by  water  with  the  formation 
of  acetylene  gas  and  calcium  hydroxid  : 

CaC2     +     2H20  C2H2     +      Ca(HO)2. 

The  gas  burns  in  air  with  a  sooty  flame  which,  when  special 
burners  are  used  to  insure  a  larger  proportion  of  oxygen,  changes 
to  an  intensely  white  light.  As  acetylene  is  an  explosive  sub- 
stance, when  mixed  with  air  or  oxygen,  great  care  should  be  used 
with  the  apparatus  for  generating  it  on  a  large  scale  (p.  383). 
The  brightness  of  the  flame  is  due  to  the  enormous  energy 
absorbed  from  the  electric  furnace  in  the  manufacture  of  CaC2 


240  THE    METALS 

and  set  free  in  the  combustion  of  acetylene.  It  is  223  kilojoules 
more  than  that  produced  by  burning  the  same  amount  of  free 
C  and  H.  The  greater  the  heat,  the  brighter  the  light. 

Calcium  Carbonate  (CaCO3). — The  purest  natural  forms  of 
this  salt  are  Iceland  spar,  calc  spar,  or  calcite,  in  rhombohedra; 
and  arragonite,  in  rhombic  prisms.  Less  pure,  but  still  crystalline 
forms,  are  marble  and  limestone.  Chalk  is  composed  of  minute 
grains  of  calcium  carbonate. 

Creta  Praeparata  (U.  S.  P.)  (Prepared  Chalk).— The  native 
chalk  is  freed  from  coarse  mineral  impurities  by  grinding  it  finely 
and  suspending  the  finer  particles  in  water,  the  coarser  ones 
settling  first.  Prepared  chalk  is  a  white  amorphous  powder, 
without  odor  or  taste,  and  insoluble  in  water.  It  is  used  as  an 
astringent  and  antacid.  Dose:  5  to  30  gr.  (0.32-1.94  gm.). 

Mistura  cretae  (chalk  mixture)  is  made  by  rubbing  together 
chalk,  sugar,  gum,  and  cinnamon  water.    Dose:  2  f.  dr.  (7.39  c.c.). 
Calcii  carbonas  praecipitatus,   CaCO3,  is  made  by  mixing 
solutions  of  calcium  chlorid  and  sodium  carbonate: 

Na-,  Na-  (CO3)"  +  Ca",  Cl',  Cl',=  Na',  Cl'  +  Na',Cl'+CaCO3. 

It  is  formed  whenever  calcion,  Ca",  meets  carbanion,  (CO3)",  and 
is  a  fine,  impalpable  white  powder,  odorless  and  tasteless,  insoluble 
in  water,  but  soluble  in  water  charged  with  carbon  dioxid. 

Liquor  Calcii  Bicarbonatis  (Calcium  Bicarbonate). — The 
increased  solubility  of  calcium  carbonate  in  carbonic  acid  water  is 
due  to  the  formation  of  calcium  bicarbonate,  Ca(HCO3)2.  This 
salt  has  not  been  isolated,  as  evaporation  leaves  the  original  car- 
bonate, by  loss  of  an  equivalent  of  H2CO3. 

Ca(HC03)2  CaC03     +      H2O      +      CO2. 

This  is  a  property  that  provides  for  an  important  movement 
of  calcium  in  nature.  Ground-waters  charged  with  carbon  dioxid 
are  able  to  dissolve  calcium  carbonate  from  minerals  and  carry  it 
to  distant  points  to  deposit  it  again  when  the  gas  evaporates.  In 
this  way  are  the  stalactites  of  caves  built  up,  layer  on  layer.  In 
the  ocean  fishes  and  other  marine  animals  get  their  calcareous 
skeletons  from  the  calcium  thus  washed  down  by  the  rivers;  in 
time  their  bones  and  shells  make  the  chalk,  limestone,  and  marble 
deposits. 

Waters  charged  with  minerals  are  unsuitable  for  washing  pur- 
poses because  of  their  hardness.  They  form  hard  or  insoluble 
salts  with  soap.  By  boiling,  the  water  loses  a  portion  of  its  hard- 
ness, owing  to  the  escape  of  the  carbon  dioxid  and  the  precipitation 


CALCIUM  241 

of  the  calcium  carbonate.  This  lost  part  is  said  to  be  temporary, 
the  remainder,  due  to  other  salts,  is  called  permanent  hardness. 
The  crust  in  steam  boilers  is  due  to  the  solid  residue  of  minerals 
left  when  the  water  has  boiled  off. 

Calcium  sulphate,  CaSO4.2H2O,  occurs  native  in  great  abun- 
dance as  gypsum  and  selenite.  It  is  also  found  in  natural  waters 
in  small  quantities,  as  it  takes  500  parts  of  water  to  dissolve  it. 
When  heated  to  107°  C.  (225°  F.)  it  loses  three-fourths  of  the 
2H2O  it  contains  and  is  then  known  as  plaster-oj-Paris,  calcii 
sulphas  exsiccatus  (U.  S.  P.).  The  expulsion  of  part  of  its  water 
has  left  the  crystals  as  a  white  powder  which,  if  supplied,  takes  up 
water  again  and  solidifies  in  a  few  minutes  as  crystalline  gypsum. 
It  expands  as  it  hardens  and,  therefore,  makes  a  sharp  cast  of 
statuary  and  masonry  decorations  in  relief.  With  it  dentists 
make  molds  of  the  gums  for  shaping  artificial  teeth,  surgeons 
apply  it  as  a  paste  to  bandages,  which  harden  to  immovable 
dressings.  The  finest  plaster  is  used  by  dentists.  This  sets  too 
quickly  for  the  surgeon,  who  generally  wants  more  time  and  who, 
therefore,  chooses  the  medium  grade.  If  common  salt  or  alum  be 
put  in  the  water,  the  bandage  dries  more  quickly.  A  mixture  of 
dry  calcium  sulphate  and  common  meal  is  used  as  a  rat  poison; 
after  eating  it  and  drinking  water  the  plaster  formed  solidifies  in 
the  stomach. 

The  calcium  phosphates  are  three  in  number:  the  tertiary  or 
normal,  Ca3(PO4)2;  the  secondary,  Ca2H2(PO4)2;  and  the  primary 
or  acid,  CaH4(PO4)2,  called  superphosphate.  In  these  formulas, 
owing  to  the  divalence  of  calcium,  the  formula  of  phosphoric  acid 
is  doubled  thus:  H6(PO4)2,  which  permits  of  substitution  of  Ca" 
for  two  atoms  of  H. 

Tricalcium  phosphate,  Ca3(PO4)2,  is  the  normal  or  bone  phos- 
phate. This  is  the  most  abundant  mineral  in  the  bodies  of  animals, 
giving  solidity  to  the  bones  and  supplying  an  essential  principle 
to  cell  formation  generally.  In  the  soil  it  occurs  in  beds  of  phos- 
phate rock,  consisting  of  the  skeletons  of  minute  organisms. 

Calcii  phosphas  prcecipitatus  (U.  S.  P.)  is  prepared  by  calcining 
bones,  dissolving  the  ash  in  hydrochloric  acid,  and  precipitating 
with  ammonium  hydroxid.  It  is  a  white,  tasteless,  odorless  pow- 
der, insoluble  in  water  and  in  alcohol.  Dose:  5  to  30  gr.  (0.32— 
1.94  gm.).  It  is  inert  unless  dissolved  by  the  aid  of  some  weak 
acid. 

Syrupus  calcii  lactophosphatis  is  a  preparation  of  the  phosphate 
made  soluble  by  a  little  lactic  and  phosphoric  acids,  and  pala- 
table by  sugar  and  orange-flower  water.  Dose:  i  to  2  f.  dr.  (3.70- 
7.39  c.c.).  The  solubility  is  due  to  a  change  of  constitution:  if  a 
weak  acid  has  been  used,  the  secondary  phosphate  results;  if  a 
16 


242  THE    METALS 

strong  acid  then  the  primary  phosphate  forms.     Both  are  quite 
soluble  in  water.     Thus,  with  a  little  hydrochloric  acid,  diluted: 

Ca3(P04)2     +      2HC1     =      CaCl2     +      2(CaHPO4) 

Tertiary  phosphate.  Secondary  phosphate. 

By  adding  concentrated  sulphuric  acid  to  the  bone  phosphate, 
the  primary  or  acid  salt  is  formed: 

Ca3(PO4)2      +      2H2SO4      =      2CaSO4     +      CaH4(PO4)2 

Tricalcium  phosphate.  Monocalcium  phosphate. 

Some  calcium  phosphate  is  indispensable  to  the  growth  of 
plants.  Removal  of  crops  impoverishes  the  soils  to  such  an  extent 
that  phosphatic  fertilizers  and  animal  manures  must  be  used 
to  restore  their  fundamental  plant  food.  It  is  not  easy  for  plants 
to  absorb  bone  meal,  though  it  is  slowly  dissolved  in  the  soil.  But 
the  soluble  acid  phosphate  under  the  name  of  superphosphate, 
restores  to  the  soil  in  a  highly  assimilable  form  that  which  it  had 
lost. 

Test  for  Calcium. — (i)  In  solution  a  calcium  salt  is  pre- 
cipitated by  a  soluble  carbonate,  such  as  sodium  or  potassium 
carbonate,  in  the  form  of  calcium  carbonate. 

(2)  Potassium  oxalate  or  ammonium  oxalate  makes  a   white 
precipitate  of  calcium  oxalate  insoluble  in  acetic  acid,  but  soluble 
in  hydrochloric  or  nitric  acids. 

(3)  A  concentrated  solution  of  a  calcium  salt  yields  a  white 
precipitate  to  sulphuric  acid. 

(4)  From    concentrated    calcium    solutions    the    hydroxids    of 
sodium  or  potassium  precipitate  white  calcium  hydroxid.     Am- 
monium hydroxid  does  not  precipitate  calcium. 

(5)  Its  flame  reaction  is  orange-red  in  color.     The  spectrum 
shows  lines  in  the  orange-red,  green,  and  blue. 


MAGNESIUM 

Symbol,  Mg.     Atomic  weight,  24. 

Occurrence. — This  metal  is  found  in  considerable  quantities, 
widely  distributed,  in  nature  in  the  minerals:  magnesite,  a  carbo- 
nate; dolomite,  a  mixed  carbonate  of  calcium  and  magnesium; 
kainite,  a  double  sulphate  of  magnesium  and  potassium  and 
various  silicates,  such  as  soapstone,  asbestos,  mica,  serpentin,  meer- 
schaum, and  hornblende,  capable  of  standing  high  temperatures. 

Preparation. — Large  amounts  are  now  separated  by  electro- 
lysis of  fused  carnallite,  which  contains  magnesium  chlorid. 

Properties. — Magnesium  is  a  white,  tough  metal,  which 
remains  untarnished  in  dry  air  for  a  long  time,  but  in  boiling 


MAGNESIUM  243 

water  it  slowly  evolves  hydrogen.  It  dissolves  readily  in  dilute 
acids,  evolving  hydrogen.  It  burns  in  air  with  an  intense  white 
flame,  useful  in  photographing.  To  make  a  flash-light  the  pow- 
der may  be  blown  through  a  flame  or  ignited  in  a  mixture  with 
potassium  chlorate.  The  strong  light  is  due  to  the  fact  that  in 
spite  of  the  great  heat  of  its  combustion  the  oxid  produced  is 
neither  melted  nor  vaporized,  but  glows  as  incandescent  solid  par- 
ticles. 

The  position  assigned  to  sodium  in  the  potassium  family 
belongs  to  magnesium  in  the  calcium  group.  It  is  found  in  more 
natural  compounds  than  calcium,  and  differs  from  it  more  than 
calcium  does  from  strontium  and  barium.  The  taste  of  all  its 
soluble  salts  shows  that  its  ion  is  bitter. 

Magnesium  Hydroxid,  Mg(HO)2.— When  a  solution  of  magne- 
sium sulphate  or  chlorid  is  treated  with  excess  of  sodium  or  potas- 
sium hydroxid,  a  white  gelatinous  precipitate  separates.  A  trace  of 
it  dissolves  and  turns  red  litmus  blue.  In  solution  of  ammonium 
chlorid  or  other  ammonium  salt  the  magnesia  dissolves.  The 
dry  Mg(HO)2  is  a  white  powder  which,  on  being  heated,  loses 
water,  changing  to  magnesium  oxid. 

Magnesium  Oxid,  MgO  (Magnesia).— This  is  best  prepared 
by  heating  the  light  carbonate.  A  white,  fine,  bulky,  and  light 
powder  is  produced,  called  calcined  magnesia.  It  is  tasteless, 
odorless,  and,  though  almost  insoluble  in  water,  it  still  turns 
moist  litmus-paper  blue.  On  standing  with  15  parts  of  water  for 
half  an  hour  it  becomes  hydrated  to  a  gelatinous  magma.  It  is 
used  as  an  antacid  and  antidote.  Dose:  5  to  60  gr.  (0.32—3.88 
gm.).  It  is  a  component  of  jerri  hydroxidum  cum  magnesii  oxido, 
the  antidote  for  arsenic  (p.  270). 

Magnesii  Oxidum  Ponderosum. — Heavy  magnesia  is  made 
by  calcining  the  heavier  variety  of  carbonate.  It  is  a  white,  fine, 
dense  powder  which  does  not  gelatinize  in  water  and  is  slower 
in  action  than  light  magnesia,  though  it  corresponds  to  it  in  other 
respects.  The  dose  is  the  same. 

Magnesium  chlorid,  MgCl2,  is  a  deliquescent  salt  formed 
by  the  action  of  hydrochloric  acid  on  the  oxid  or  carbonate.  It 
is  present  in  various  bitter,  saline  mineral  waters,  to  which  it 
imparts  a  laxative  property. 

Magnesium  carbonate,  MgCO3  (normal  or  neutral  carbonate), 
is  formed  by  passing  carbon  dioxid  through  a  mixture  of  water 
and  the  basic  carbonate. 

Magnesii  Carbonas  (U.  S.  P.  )  (MgCO3)4,  Mg(HO)2 .  5H2O.— 
When  a  solution  of  magnesium  sulphate  or  chlorid  is  boiled 
with  one  of  sodium  carbonate,  CO2  is  evolved  and  a  white  gelat- 
inous precipitate  forms,  which  is  a  varying  mixture  of  carbonate 


244  THE    METALS 

and  hydroxid.1  If  the  solution  be  dilute  and  cold,  very  little 
CO2  is  evolved.  The  deposit  is  white,  light,  and  bulky,  and  is 
called  magnesii  carbonas  levis,  or  magnesia  alba.  It  is  mostly 
MgCO3,  neutral  carbonate.  If  the  solution  used  be  concen- 
trated and  hot,  and  the  water  be  boiled  off,  a  denser  product  is 
obtained,  containing  some  hydroxid,  and  called  magnesii  car- 
bonas ponderosus.  This  is  sometimes  dispensed  in  large  cubes. 
Both  forms  are  white,  light,  faintly  earthy  in  taste,  and  insoluble 
in  water.  They  neutralize  the  acids  of  indigestion  and  the  cor- 
rosive acid  poisons. 

Magnesii  bicarbonas  (fluid  magnesia)  is  a  solution  of  the 
carbonate  in  water  charged  with  carbon  dioxid.  It  is  alkaline 
and  bitter  in  taste. 

Mistura  magnesias  et  asafoetidse  (Dewees'  carminative)  con- 
tains the  carbonate,  tincture  asafetida,  tincture  opium,  sugar,  and 
water.  It  is  given  for  flatulent  diarrhea.  Dose:  i  to  4  fl.  dr.  (3.75— 
15.00  c.c.). 

Magnesium  sulphate,  MgSO4.7H2O  (Epsom  salt),  occurs  in 
sea-waters  and  in  waters  of  bitter  saline  mineral  springs.  The 
salt  is  prepared  by  the  action  of  sulphuric  acid  on  magnesium 
carbonate,  prismatic  or  acicular  crystals  forming,  which  are 
freely  soluble  and  neutral,  with  a  cool  bitter  taste.  It  is  a  favor- 
ite cathartic  when  free  watery  discharges  are  desired.  The  purged 
fluid  flows  from  the  vessels  into  the  intestines  by  osmotic  pressure. 
To  mask  the  bitter  taste  possessed  by  the  soluble  magnesium  salts, 
effervescing  solutions  are  used,  in  which  carbon  dioxid  is  liberated 
from  a  carbonate  by  the  action  of  citric  acid. 

Magnesii  sulphas  effervescens  is  a  granular  mixture  of  magnesium 
sulphate  and  sodium  bicarbonate  with  tartaric  and  citric  acids. 
Dissolved  in  sweetened  water  the  CO2  set  free  masks  the  bitter 
taste  of  the  sulphate. 

Liquor  Magnesii  Citratis  (Effervescing  Citrate  of  Magnesia).— 
This  is  a  palatable  solution,  quickly  mixed  and  tightly  stoppered 
so  as  to  retain  the  carbon  dioxid.  It  contains  magnesium  car- 
bonate, citric  acid,  syrup,  potassium  bicarbonate,  and  water. 
Dose  as  a  cathartic:  2  to  8  fl.  oz.  (60-236  c.c.). 

Detection  of  Magnesia.— The  ion  magnesium  is  divalent 
and  colorless,  like  that  of  calcium.  Its  carbonate,  like  that  of 
other  alkaline  earths,  is  insoluble  in  water,  but  unlike  the  others, 
soluble  in  ammonium  salts  like  the  chlorid.  Hence,  to  separate 
it  from  them,  ammonium  chlorid  is  added  to  the  suspected  solu- 
tion until  it  ceases  to  precipitate  with  ammonium  hydroxid. 

1  In  another  place  (p.  228)  it  has  been  stated  that  the  alkaline  carbonates  are 
split  by  solution  in  water  forming  some  hydroxid  which  turns  red  litmus  blue. 
Magnesion,  Mg',  is  thrown  down  by  both  the  anions  (CO3)'  and  (HO)'  thus  formed 
by  hydrolysis. 


BARIUM 


245 


If  now  ammonium  carbonate  be  added,  carbonates  of  calcium, 
strontium,  and  barium  are  precipitated,  leaving  magnesium  in 
solution.  After  filtration  a  solution  of  disodium  phosphate  'is 
added  to  the  filtrate.  There  being  ammonia  present  already, 
there  is  deposited  a  crystalline  precipitate  of  ammonium  mag- 
nesium phosphate,  MgNH4PO4.  All  the  heavy  metals  must 
have  been  separated  first  by  hydrogen  sulphid  or  ammonium 
sulphid.  There  is  no  characteristic  color  to  the  magnesium 
flame. 

STRONTIUM 
Symbol,  Sr.     Atomic  weight,  87.68. 

This  metal  and  barium  are  more  closely  allied  to  calcium  than 
is  magnesium,  just  as  cesium  and  rubidium  resemble  potassium 
more  than  does  sodium.  They  are  much  rarer  than  calcium  and 
magnesium  and  have  little  medical  interest,  though  barium  figures 
as  a  poison  because  of  its  employment  in  pyrotechnics.  Strontium 
is  found  in  nature  combined  in  its  sulphate,  celestite,  and  in  its 
carbonate,  strontianite.  The  metal  is  obtained  readily  by  electro- 
lysis of  its  fused  chlorid.  It  is  yellowish,  rather  tough,  like  cal- 
cium, unites  with  oxygen  in  the  air,  and  reacts  energetically  with 
water,  evolving  hydrogen.  Its  ion,  Sr",  is  divalent  and  behaves 
so  much  like  calcion  that  it  is  not  worth  while  to  consider  its 
salts  in  detail.  The  bromid,  iodid,  and  salicylate  are  official  and 
are  used  in  medicine  with  essentially  the  same  indications  as  the 
corresponding  salts  of  potassium.  The  chief  use  is  in  the  making 
of  fireworks,  growing  out  of  the  beautiful  dark-red  color  of  its 
flame.  Its  detection  depends  on  the  fact  that  it  is  the  only 
substance  that  gives  this  flame  reaction.  The  spectrum  shows 
lines  in  the  red,  orange-red,  and  blue. 

BARIUM 

Symbol,  Ba.     Atomic  weight,  137. 

Occurrence. — This  metal  occurs  in  nature  as  the  sulphate, 
barite,  and  as  the  carbonate,  witherite.  It  is  obtained  by  passing 
the  electric  current  through  the  fused  chlorid. 

Properties. — It  is  a  white  metal  resembling  calcium  and 
strontium  in  that  it  oxidizes  in  the  air  and  reacts  energetically 
with  water.  Its  ion  Ba",  is  divalent,  colorless,  and  poisonous. 
It  is  recognized  by  the  heavy  white  precipitate  with  sulphuric  acid 
and  the  sulphates,  and  by  the  yellowish-green  color  of  its  flame. 

The  hydroxid,  Ba(HO)2,  or  baryta  water,  is  more  soluble  and 
more  basic  than  lime-water,  and  is  used  to  neutralize  acids  and 
test  for  carbon  dioxid. 

Ba(OH)2     +      C02     =      BaC03     +      H2O. 

Barium  hydroxid.  Barium  carbonate. 


246  THE    METALS 

The  soluble  salts,  barium  nitrate,  Ba(NO3)2,  and  barium  chlorid, 
BaCl2,  are  used  as  reagents  for  precipitating  sulphanion,  SO/',  in 
barium  sulphate,  the  most  insoluble  of  sulphates  and  of  barium 
salts: 

Ba",  (N03)',  (N03)'  +  K-,  K%  (SO4)"  =  2K%  (NO3)'  +  BaSO4. 

As  fast  as  barion  is  neutralized  by  the  union  with  the  sulphan- 
ion, BaSO4  is  precipitated,  insoluble,  and  therefore  undissociated. 
Because  of  its  resistance  to  acids  and  solvents  it  wears  well  as  a 
pigment  under  the  name  "  permanent  white." 

Certain  salts  of  barium  used  in  pyrotechny,  in  wood-staining, 
and  in  glass-making  sometimes  figure  in  toxicology  as  irritant 
poisons  which,  when  absorbed,  cause  cardiac  depression  and  con- 
vulsions. The  chlorid  and  the  nitrate  occur  in  white,  soluble 
crystals  resembling  the  ordinary  purgative  "salts,"  for  which 
they  have  been  taken  by  mistake. 

Symptoms. — Gastro-intestinal  irritation  is  shown  by  vomiting 
and  diarrhea,  with  straining  and  abdominal  pain.  After  absorp- 
tion dilation  of  the  pupils  with  convulsions,  paralysis,  and  heart 
failure  may  supervene. 

Fatal  Dose. — About  100  gr.  (6.5  gm.)  of  the  chlorid  proved 
fatal  to  a  woman,  although  by  gradually  increasing  the  daily 
quantity,  Pivondi  was  enabled  to  take  in  divided  doses  119  gr. 
(7.7  gm.)  in  a  day. 

Fatal  Period. — Death  occurred  in  one  case  in  one  hour,  in 
another  case  in  fifteen  hours,  in  another  case  in  thirty-four  hours, 
and  again  as  late  as  a  week  after  taking  the  poison. 

Treatment. — The  best  chemical  antidote  is  magnesium  sul- 
phate (Epsom  salts)  or  sodium  sulphate  (Glauber's  salts).  Both 
have  the  power  to  precipitate  the  barium  as  insoluble  sulphate. 
The  stomach  should  then  be  washed  out  with  milk  and  water. 
Anodynes  are  indicated  for  pain;  heat  and  stimulants  for  the 
cardiac  depression. 

Post=mortem  Appearances.— Any  or  all  of  the  signs  of  gastro- 
intestinal inflammation  may  be  present — i.  e.,  patches  of  redness, 
swelling,  softening,  effusions,  ulcerations,  and  even  perforation. 

Experiments  on  rabbits  show  that  after  chronic  poisoning  for 
thirty  days  all  the  organs  contain  barium — the  bones  most  of  all, 
the  kidneys,  brain,  and  spinal  cord  show  a  less  amount,  the  liver 
still  less,  and  traces  only  are  in  the  lungs,  heart,  and  muscles. 

Tests. — i.  Dilute  sulphuric  acid  precipitates  barium  sulphate, 
which  is  insoluble  in  hydrochloric  or  nitric  acid. 

2.  Neutral  potassium  chr  ornate  gives  a  yellow  precipitate, 
insoluble  in  water,  but  soluble  in  hydrochloric  or  nitric  acid. 


RADIUM  247 

3.  A  green  hue  is  given  to  a  colorless  flame  when  a  barium 
salt  is  held  in  it  by  a  loop  of  platinum  wire  moistened  with  hydro- 
chloric acid. 

Detection, — Having  dissolved  the  organic  matter  by  hydro- 
chloric acid  and  potassium  chlorate  and  precipitated  most  of  the 
common  metals  by  hydrogen  sulphid  and  ammonium  sulphid, 
the  nitrate  is  treated  with  ammonium  carbonate,  which  precipitates 
barium,  strontium,  and  calcium  carbonates.  This  precipitate  is 
dissolved  in  nitric  acid  and  dried  until  the  free  acid  is  driven  off. 
The  residue  is  treated  with  equal  parts  of  absolute  alcohol  and 
ether,  which  dissolve  calcium  nitrate,  but  leave  the  others  undis- 
solved.  The  calcium  solution  gives  a  white  precipitate  to  sul- 
phuric acid.  The  residue,  dissolved  in  water  and  treated  with  a 
little  acetic  acid  and  potassium  chromate,  gives  a  yellow  precipitate 
of  barium  chromate.  The  nitrate,  treated  with  ammonium  car- 
bonate and  ammonia,  gives  a  white  precipitate  of  strontium  carbo- 
nate. 

By  another  method  the  organic  matter  may  be  burnt,  the  ash 
fused  with  sodium  carbonate,  dissolved  in  hydrochloric  acid,  and 
tested  as  stated  above. 

RADIUM 

Symbol,  Rd.     Atomic  weight,  226. 

A  white  and  brilliant  metal  of  the  alkaline  earths,  closely  related 
to  barium. 

Occurrence. — Radium  is  found  in  excessively  minute  quan- 
tities in  pitchblende,  a  black  mineral  found  in  Colorado,  Texas,  and 
Bohemia;  the  mineral  is  rich  in  uranium  oxid. 

Preparation. — By  tedious  and  difficult  processes  of  fractional 
crystallization  a  ton  of  pitchblende  will  yield  ij  gr.  (o.i  gm.)  of 
radium  chlorid.  By  electrolysis  with  a  mercury  anode,  this  yields 
radium  amalgam,  which  on  distillation  in  hydrogen  separates  the 
pure  silvery  white  metal,  radium.  It  decomposes  and  dissolves 
in  water,  and  oxidizes  in  air,  but  as  chlorid  or  bromid  forms  a  per- 
manent salt. 

Physical  Properties.— Radium  chlorid  is  obtained  as  small, 
colorless,  self-luminous  crystals.  It  burns  with  a  brilliant  red 
light,  which  gives  a  characteristic  spectrum  of  vivid  lines.  From 
its  properties  an  atomic  weight  has  been  deduced  of  226.  This 
is  the  third  highest  known;  the  two  elements  above  it  in  weight, 
uranium  and  thorium,  have  the  same  remarkable  property  of 
radio-activity. 

Radio-activity  is  a  property  first  discovered  by  Becquerel  in 
the  uranium  salts  obtained  from  pitchblende.  They  emit  spon- 
taneously invisible  radiations,  which  penetrate  opaque  substances 
and  show  their  presence  by  blackening  sensitive  photograph 


248  THE    METALS 

films  and  by  conducting  away,  through  the  air,  the  charge  of  elec- 
trified bodies.  The  rays  from  the  electrified  current  streaming 
from  the  cathode  of  a  Crookes  vacuum  tube,  and  the  Rontgen 
rays  given  off  from  the  glass  of  that  tube  when  bombarded  by 
radiant  matter,  have  these  properties;  but  the  rays  of  polonium, 
uranium,  thorium,  and  radium  are  produced  incessantly  and  irre- 
sistibly without  the  outside  stimulus  of  electric  excitement.  Radium 
has  radio-activity  intensified  2,000,000  times  beyond  the  standard 
fixed  by  uranium.  The  radium  emission,  like  that  of  the  Crookes 
tube,  is  sufficiently  intense  to  produce  fluorescence  in  barium 
platinocyanid,  which  is  not  the  case  with  the  rays  from  uranium 
and  thorium. 

The  intensity  of  this  radiating  action  is  measured  definitely  by 
the  rate  of  leakage  of  electricity  in  a  certain  period,  from  a  charged 
electrometer,  due  to  the  increased  conductivity  of  a  given  quantity 
of  air  caused  by  the  " ionizing"  influence  of  the  emitted  rays. 
The  unit  of  intensity  is  the  radio-activity  of  uranium.  Thus, 
when  it  is  said  that  a  sample  of  radium  salt  has  a  radio-activity 
of  5000,  it  is  meant  that  the  rays  emitted  by  the  sample  raise  the 
conductivity  of  the  air  5000  times  as  much  as  would  an  equal 
weight  of  uranium. 

Radium  emits  three  kinds  of  rays  and  a  radio-active  gaseous 
emanation.  The  three  rays  are  named  a  (alpha)  or  ionic,  /5  (beta) 
or  cathodic,  and  y  (gamma)  or  (Ethereal,  like  the  Rontgen  rays. 

The  alpha  species  consist  of  atoms  of  helium  of  twice  the  mass 
of  hydrogen  atoms;  they  are  charged  positively,  are  projected 
with  a  velocity  of  about  20,000  miles  per  second,  can  be  deflected 
by  a  magnet,  are  readily  absorbed  by  surrounding  objects,  have 
little  penetrative  power,  and  ionize  gases  so  that  electrified  bodies 
near  by  are  rapidly  discharged.  They  emit  heat  and  burn  the  skin. 

The  beta  species  are  flying  electrons,  one  eighteen  hundredth 
the  weight  of  a  hydrogen  atom;  they  are  negatively  charged, 
strongly  affect  the  silver  salts  of  a  photographic  plate,  traverse  glass 
and  many  opaque  solid  partitions,  and  are  influenced  by  a  magnet; 
all  100  times  more  strongly  than  the  alpha  rays. 

The  gamma  species,  like  waves  in  the  aether,  move  in  straight 
paths,  are  neutral  electrically,  are  not  deflected  by  a  magnet,  and 
penetrate  most  substances,  even  thin  plates  of  lead,  powerfully. 

The  gamma  rays  are  considered  to  be  identical  with  the  irregular 
and  intense  pulses  of  the  Rontgen  rays  emitted  from  the  high  vacuum 
Crookes'  tube  when  excited  by  electricity. 

The  emanation  is  not  projected  at  a  high  speed,  but  wells 
forth  as  a  luminous  gas,  slowly,  without  ceasing,  imparting  feeble 
luminosity  to  any  body  it  may  touch.  In  a  dark  room  it  can  be 
seen,  by  its  luminosity,  to  be  subject  to  draughts,  to  flow  inside 


RADIUM  249 

glass  tubes,  to  penetrate  cotton-wool,  sulphuric  acid,  and  thin 
metallic  foil,  but  to  be  stopped  by  mica.  It  is  unaffected  by  all 
chemical  reagents,  but  is  condensed  by  low  temperatures.  Its 
boiling-point  is  —150°  C.  (  —  238°  F.).  It  imparts  temporary 
radio-activity  to  surrounding  objects,  apparently  by  a  deposit  of 
invisible  powder  so  minute  that  in  years  the  accumulation  would 
not  be  weighable.  Neutral  electrically,  it  can  ionize  other  gases 
so  as  to  disperse  electric  charges.  Even  when  confined  with  the 
utmost  care,  in  a  month  it  disappears  entirely,  no  matter  if  it  be 
hermetically  sealed.  The  colored  bands  characteristic  of  the 
emanation  spectrum  are  seen  in  a  few  days  to  show  the  yellow- 
green  line  typical  of  helium,  and  eventually  the  lines  are  those 
of  helium  throughout.  If  the  emanation  be  dissolved  in  water 
it  generates  the  gas  neon,  if  dissolved  in  a  solution  of  copper 
sulphate  it  generates  argon,  but  in  neither  liquid  is  helium  a  product 
of  the  disintegration. 

Heat  Radiation. — Pure  radium  chlorid,  without  cessation  and 
for  an  indefinite  period,  evolves  heat  enough  to  maintain  itself  at 
a  constant  temperature  of  1.5°  C.  (2.7°  F.)  above  other  objects  in 
the  room.  A  gram  weight  gives  off  100  calories  every  hour,  an 
amount  sufficient  to  raise  i  gm.  of  ice-water  to  the  boiling-point. 
In  a  year  the  amount  of  energy  put  forth  is  enormous,  and  yet 
the  loss  of  weight  is  so  infinitesimal  that  the  most  delicate  balance 
will  not  indicate  it.  The  heat  results  from  the  atomic  collisions. 

Transmutation. — The  rate  of  emission  is  unlike  that  of  a 
chemical  process  in  that  it  is  unaltered  by  change  of  temperature. 
Even  the  cooling  by  immersion  in  frozen  hydrogen  has  no  effect. 
The  heat  given  off  in  the  disintegration  of  radium  is  a  million 
times  as  much  as  that  of  its  combustion  or  of  any  chemical  proc- 
ess. There  are  two  main  groups  of  true  radio-elements:  (i)  the 
series  formed  by  the  disintegration  of  uranium,  and  (2)  the  series 
of  similar  products  from  thorium.  Together  they  include  28  well- 
defined  radio-elements,  of  which  only  the  parents  uranium  and  thor- 
ium were  known  before  the  use  of  radio-active  methods.  Lineally 
descended  by  the  spontaneous  breaking  up  of  uranium  are  ten  ele- 
ments: uranium  X,  ionium,  radium,  radium-emanation,  radiums  A, 
B,  C,  D,  E,  and  F.  Uranium  is  the  progenitor  of  another  group  of 
six  radio-elements — actinium,  radio-actinium,  actinium-emanation, 
and  actiniums  A,  B,  and  C.  The  thorium  series  (2)  includes  a  sim- 
ilar progeny  of  ten  successive  elements,  among  which  are  to  be  noted 
mesothorium  and  thorium-emanation. 

Induced  Radio-activity. — If  a  sealed  tube  containing  radium 
be  immersed  for  a  day  in  normal  salt  solution  and  then  removed, 
the  solution  for  a  few  days  shows  all  the  radio-active  powers, 
though  in  a  lower  degree,  which  diminishes  rapidly. 

Chemical  Properties. — The  emitted  rays  convert  oxygen  into 


250  THE    METALS 

ozone  and  change  yellow  phosphorus  to  red.  The  alpha  rays  imme- 
diately coagulate  a  sensitive  solution  of  globulin.  The  beta  and 
gamma  rays  liberate  iodin  from  iodoform  in  the  presence  of  oxygen. 

Physiologic  Effects. — Under  the  influence  of  the  rays, 
nutrition  is  profoundly  modified,  the  development  of  growing 
animals  arrested,  and  after  prolonged  exposure  some  are  killed. 
Radium  chlorid,  when  uncovered  at  a  short  distance,  soon  in- 
flames the  skin,  producing  painless  ulcers;  the  partially  blind 
are  enabled  to  see  luminous  appearances,  and  by  its  injurious 
effects  upon  the  nervous  system  it  induces  paralysis  and  death. 
Cautiously  applied  directly  to  the  part,  it  is  used  to  break  up 
superficial  cancers  and  growths,  like  lupus,  rodent  ulcer,  and 
the  hypertrophied  thyroid  of  goiter.  For  this  purpose  at  least 
i  mg.  of  1,000,000  activity  is  required.  As  it  destroys  bacteria, 
it  has  been  hoped  that  inhalation  of  the  emanation  or  some  radio- 
active vapor  will  prove  helpful  in  tuberculosis  of  the  lung.  As 
yet  no  such  specific  curative  power  has  been  proven. 

Intra=atomic  Matter.— Viewed  in  the  light  of  recent  discov- 
eries, the  picture  of  the  constitution  of  substance — the  atomic 
theory — has  its  details  ^better  defined  than  ever  and  made 
more  true  to  nature.  The  notion  that  matter  is  granular  or 
atomic  still  subsists,  as  it  rests  upon  the  necessity  of  chemistry 
for  separate  combining  units  which  are  centers  of  force.  But 
the  physical  integrity  of  the  chemical  atom  can  no  longer  be  main- 
tained. Through  the  highly  exhausted  vacuum  of  a  Crookes 
tube  negative  electricity  streams  in  electrons  of  radiant  matter, 
which  are  neither  molecules  nor  atoms.  These  cathode  rays  are 
convection  currents  of  electricity,  like  the  stream  of  ions  in  liquid 
electrolytes,  but  differ  from  them  in  having  carriers  1800  times 
less  massive  than  the  hydrogen  atom.  "The  negatively  electrified 
particles  have  the  same  charge  and  the  same  mass,  whatever  be 
the  nature  of  the  gas  in  the  tube  or  the  nature  of  the  electrode. 
They  therefore  form  an  invariable  constituent  of  the  atoms  and 
molecules  of  all  gases,  and  presumably  of  all  liquids  and  solids" 
(Thomson). 

The  electron  theory  assumes  that  electric  conduction  is  the 
property  of  intra-atomic  units  of  negative  electricity  which  are  de- 
tached from  the  atoms.  The  atom  may  be  considered  as  an  open 
structure  with  vacant  spaces  relatively  large  and  a  cluster  of  these 
much  smaller  electrons  in  swift  gyration  within  the  relatively 
enormous  atomic  space,  controlled  by  electric  forces  which  nor- 
mally in  the  aggregate  are  neutral.  The  chemical  characteristics 
of  the  atom  are  due  to  its  mass,  which  is  proportional  to  the  number 
of  its  electrons.  The  ions  of  solutions  are  atoms  carrying  more  or 
less  of  these  electrons  than  belong  to  them  in  their  normal  or 


ALUMINIUM  251 

neutral  state.  If  more,  they  are  positive,  if  less,  negative.  When 
a  molecule  of  NaCl  dissociates,  the  Na*  atom  surrenders  an  elec- 
tron to  the  Cl'  and  their  neutrality  is  lost.  Valency  is  electric 
in  character.  The  electropositive  univalent  atom,  such  as  hydro- 
gen, engaged  in  a  chemical  action  becomes  ionized  on  losing  one 
electron.  The  electronegative  univalent  ion,  such  as  chlorin, 
becomes  stable  when  it  loses  one  electron.  The  divalent  positive 
oxygen  atom  becomes  an  ion  in  gaining  two  electrons,  and  so  on. 
Valency  on  this  hypothesis  is  an  effect  of  the  number  of  electrons 
that  can  get  free  from  or  are  caught  up  by  the  aggregation  of 
electrons  which  constitute  the  particular  kind  of  atom.  Radio- 
activity is  an  effect  of  perturbations  of  the  intra-atomic  forces 
and  a  subversion  of  the  normal  system,  which  is  attended  by  the 
loss  of  energy  emitted  in  rays,  the  disintegration  of  the  atom,  and 
such  transmutations  of  substances  as  are  seen  in  the  radium  emana- 
tions (p.  249). 

Radio=activity  Common. — Many  ordinary  things  are  found  to 
be  radio-active  in  an  exceedingly  minute  degree,  such  as  ground 
air  from  cellars  and  caves  and  newly  fallen  snow  and  rain,  surface 
waters  and  that  of  mineral  springs,  tinfoil,  glass,  silver,  lead, 
copper,  zinc,  aluminium,  platinum.  But  marked  radio-activity 
is  a  property  of  the  elements  of  heavy  atomic  weight  only. 


IE.— THE  EARTH  METALS 

ALUMINIUM 

Symbol,  Al.     Atomic  weight,  27. 

Occurrence. — This  is  the  only  element  belonging  to  the 
group  of  metals  of  the  earths  which  is  at  all  common  or  which 
has  any  practical  value.  It  ranks  next  to  oxygen  and  silicon  in 
abundance  and  is  of  great  importance,  whereas  the  others  are 
exceedingly  rare  and  of  little  interest.  The  members  of  this 
group,  aluminium,  scandium,  yttrium,  lanthanum,  gallium,  ytter- 
bium, etc.,  all  form  trivalent  ions.  Aluminium  silicate  is  not  only 
a  constituent  of  many  crystalline  rocks,  but  is  also  the  chief  com- 
ponent of  clays  and  slates.  Nearly  all  minerals,  except  sandstone 
and  limestone,  are  ore  beds  of  it.  Every  brick  has  nearly  a 
pound  of  this  metal  in  it.  A  native  aluminium  silicate  is  official 
under  the  name  of  kaolinum.  It  is  a  soft,  white  powder,  clay-like 
in  taste,  insoluble  in  water.  It  is  used  in  making  pill  masses 
and  also  in  the  cataplasma  kaolini,  U.  S.  P.,  which  contains 
kaolin,  boric  acid,  thymol,  methyl  salicylate,  oil  of  peppermint,  and 
glycerin.  It  is  used  as  an  antiseptic,  hygroscopic,  plastic  dressing. 


252  THE    METALS 

Preparation. — Aluminium  oxid  is  fused  in  iron  crucibles  by 
the  heat  of  the  electric  current,  which  then  decomposes  it,  the 
metal  seeking  the  cathode  container,  and  the  oxygen  uniting  with 
the  carbon  anode  to  form  carbon  monoxid.  To  obtain  fusion  at  a 
lower  temperature  cryolite,  a  double  fluorid  of  aluminium  and 
sodium,  is  first  melted  as  a  bath  in  which  the  oxid  fuses  and  breaks 
up  and  the  used-up  oxid  of  aluminium  is  replaced  as  the  process 
requires. 

Properties. — Aluminium  is  a  bluish-white,  silvery  metal, 
changing  very  little  on  exposure  to  the  air.  It  is  protected  from 
deep  rust  by  an  imperceptibly  thin  film  of  oxid,  which  quickly 
forms  and  firmly  adheres.  It  can  be  drawn  into  hair-like  wire 
and  beaten  into  very  thin  lea}  for  "  silvering."  As  it  does  not 
blacken,  like  silver,  and  is  extremely  light  (specific  gravity  2.7), 
it  is  often  used  for  household  ware.  Melting  at  700°  C.  (1292° 
F.),  it  is  easily  molded.  It  is  a  good  conductor  of  heat  and  elec- 
tricity. Its  drawbacks  are  its  softness,  its  inability  to  resist  the 
action  of  salt  solutions,  and  its  solubility  in  alkalis.  At  high 
temperatures  it  combines  with  oxygen,  giving  a  brilliant  light 
and  great  heat.  Two  alloys  of  great  stability  are  in  use:  alu- 
minium bronze,  which  is  golden  yellow,  and  magnalium,  white; 
the  latter  contains  about  10  per  cent,  of  magnesium. 

It  is  attacked  and  dissolved  by  acids: 

Al       +       3HC1       =       A1C13       +       aH. 

The  ion  of  aluminium  is  trivalent,  Al*",  and  colorless,  forming 
salts  which  are  astringent  and  soluble.  These  salts  when  dissolved 
resemble  the  alkaline  carbonates  in  that  they  are  split  up  by 
water  into  the  hydroxid  and  acid.  The  hydroxid  being  a  weak 
base,  the  hydrion  of  the  strong  acid  makes  the  reaction  acid,  thus: 

A1C13       +       3H20  A1(OH)3       +       3HC1. 

The  proof  of  this  dissociation  of  A1C13  is  found  in  the  fact  that 
the  original  salt  is  not  obtained  when  the  water  is  evaporated. 

Aluminium  hydroxid,  A1(OH)3,  hydrated  alumina,  is  formed 
as  a  gelatinous  precipitate  from  solution  of  aluminium  salts  on 
the  addition  of  a  small  quantity  of  an'  alkali  or  alkaline  carbonate. 

A12(S04)3     +     6NH4OH  3(NH4)2S04     +     2A1(OH)3. 

If  the  liquid  contain  suspended  particles  or  coloring-matter, 
these  are  carried  down,  and  give  a  color  to  the  dried  precipitate, 
which,  under  the  term  lake,  is  used  as  a  pigment.  Aluminii  hydrox- 
idum  (U.  S.  P.)  is  a  light,  white,  amorphous  powder,  without 


ALUMINIUM  253 

taste,  wholly  insoluble  in  water  or  alcohol,  but  soluble  in  strong 
acids  or  alkaline  solutions.     Dose:  3  to  15  gr.  (0.2-1.0  gm.). 
When  heated  to  redness  the  hydroxid  changes  to  oxid: 

2A1(OH)3     =      A12O3     +     3H2O. 

The  hydroxid  is  weakly  basic,  forming  with  acids  three  kinds 
of  salts,  according  as  one,  two,  or  three  hydroxyl  groups  are 
replaced  by  the  acid  ions.  Although  precipitated  by  caustic 
potash  or  soda  in  small  amounts,  the  precipitate  dissolves  in 
excess  of  these  alkalis,  forming  soluble  aluminates.  Metallic 
aluminium  dissolves  in  the  caustic  potash  or  soda,  with  the  for- 
mation of  aluminate  and  the  evolution  of  hydrogen: 

3KHO     +     Al  K3A1O3     +     3H. 

This  reaction  shows  that  its  hydroxid,  A1O3H3,  acts  in  this  case 
as  an  acid,  splitting  off  acid  hydrogen  from  its  hydroxyl  groups. 
Like  a  tribasic  acid,  it  yields  three  anions,  (H2A1O3)',  (HA1O3)", 
and  (A1O3)'".  Neither  the  acid  nor  basic  quality  can  be  strong 
in  a  substance  which  plays  either  part  according  to  circumstances. 
Much  concentration  of  the  acid-hydrogen  ion  and  the  basic- 
hydroxyl  ion  would  cause  the  formation  of  undissociated  water, 
as  when  a  strong  base  and  acid  meet.  Unlike  the  magnesium 
salts,  aluminium  hydroxid  is  not  soluble  in  excess  of  ammonia. 
The  absence  of  solvent  power  is  due  to  the  weak  basicity  of 
ammonia. 

Aluminium  hydroxid  is  so  weakly  basic  that  it  does  not  take 
carbonic  acid  from  the  air  or  water.  No  carbonate  is  ever  formed, 
but  the  silicate  is  carried  suspended  as  a  fine  powder  by  rivers 
and  deposited  in  quiet  waters  as  clay. 

Aluminium  oxid,  A12O3,  alumina,  occurs  nearly  pure  in  nature 
as  a  hard  mineral  corundum.  Sapphire  is  a  blue  and  ruby  is  a 
red  variety,  colored  by  admixture  of  cobalt  or  chromium.  When 
obtained  by  calcining  the  hydroxid  it  is  a  light,  white,  odorless 
powder,  which  fuses  at  a  high  heat  and  forms  hard  crystals  on 
cooling.  A  hard  granular  variety,  colored  dark  by  iron  oxid,  is 
known  as  emery. 

Aluminium  chlorid,  A1C13,  is  prepared  by  the  action  of 
hydrochloric  acid  on  aluminium  hydroxid.  It  is  a  very  hygro- 
scopic, white  crystal,  used  in  organic  chemistry  with  mixtures  of 
a  hydrogen  compound  and  a  chlorin  compound,  to  promote  the 
union  of  the  hydrogen  of  one  with  the  chlorin  of  the  other,  and 
causing  the  residues  to  combine  in  a  synthetic  compound. 

Aluminium  sulphate,  A12(SO4)3  +  i8H2O,  is  prepared  by 
heating  aluminium  silicate  or  aluminium  hydroxid  with  sulphuric 


254  THE    METALS 

acid.  It  is  a  white  crystalline  powder,  freely  soluble  in  water 
and  insoluble  in  alcohol.  It  is  used  in  medicine  as  a  local  as- 
tringent. Owing  to  the  weakness  of  aluminium  hydroxid  as  a 
base,  this,  like  the  other  salts,  is  hydrolyzed  by  water,  so  that  an 
appreciable  per  cent,  of  hydrion  causes  it  to  react  acid.  This 
salt  is  used  as  the  acid  factor  in  some  baking  powders  (see  p. 
229).  It  does  not  crystallize  so  well  as  alum,  but  by  using  pure 
materials  in  its  manufacture  better  results  are  obtained  than  for- 
merly. 

Alum  (Alumen,  U.  S.  P.). — This  name  was  first  applied  to  the 
double  sulphate  of  aluminium  and  potassium,  A1K(SO4)2,  i2H2O. 
Mixed  in  the  right  proportions,  solutions  of  potassium  sulphate 
and  aluminium  sulphate  will  form  beautiful  regular  octahedra 
with  a  sweetish  astringent  taste  and  acid  reaction.  It  is  soluble 
in  water,  but  insoluble  in  alcohol.  Dose:  10  to  15  gr.  (0.66-1.00 
gm.). 

Common  alum  is  a  type  of  a  large  series  of  isomorphous  salts, 
which  are  double  sulphates  of  alkaline  metals  and  aluminium  or 
some  member  of  the  iron  group.  A  univalent  and  a  trivalent 
metal  replace  the  four  atoms  of  hydrogen  in  2(H2SO4). 

Ammonium  ferric  alum  is  NH4Fe(SO4)2.i2H2O. 

Potassium  chromium  alum  is  KCr(SO4)2.i2H2O. 

Alumen  Exsiccatum  (Dried  or  Burnt  Alum). — The  effect  of 
heat  on  alum  is  first  to  melt  the  crystals  and  next  to  drive  off  the 
water,  leaving  a  spongy  white  mass,  which  is  slowly  soluble  in 
water,  with  a  local  astringent  and  mild  caustic  effect  on  animal 
tissues. 

Toxicology. — Alum  coagulates  albumin  and  pepsin  and 
retards  the  peristaltic  movements  of  the  bowels,  thus  arresting 
digestion.  When  absorbed,  it  constricts  the  capillaries,  lessening 
mucous  secretions,  and  stopping  hemorrhages  from  capillary' 
vessels.  It  is  a  prompt  irritant  emetic,  and  has  so  many  incom- 
patibles  that  it  is  best  given  alone. 

Excessive  doses  of  this  salt  have  produced  irritant  symptoms, 
sometimes  ending  in  death.  Medicolegal  interest  in  alum  is 
practically  limited  to  the  question  of  its  action  when  used  as  a 
constituent  of  certain  baking-powders  which  are  consumed  by 
the  ton  in  domestic  bread-making.  In  these  powders  sodium 
bicarbonate  furnishes  gaseous  carbon  dioxid,  which  is  liberated 
by  the  action  of  the  alum  present,  leaving  in  the  bread  sodium 
sulphate  and  aluminium  hydroxid.  The  fact  that  many  thou- 
sands of  persons  use  these  powders  without  any  perceptible  injury, 
local  or  systemic,  apparently  indicates  either  that  the  aluminium 
hydroxid  escapes  solution  and  absorption  or  that,  if  changed  to  a 
soluble  chlorid  by  the  gastic  juice,  the  amount  absorbed  must 


ALUMINIUM  255 

be  harmless.  At  the  same  time  it  is  proper  to  note  that  large 
doses  given  to  dogs  and  cats  subcutaneously  cause  paralysis  of 
sensation  and  motion,  with  fatty  degeneration  of  the  liver  and 
kidneys.  The  safest  view  is  to  hold  alum  as  an  unnecessary 
addition  to  bread,  and  certainly  of  no  value  as  food.  Its  presence 
in  any  but  the  smallest  amount  should  be  considered  proof  of 
adulteration. 

Domestic  niters  are  often  fitted  with  attachments  for  adding 
alum  to  the  raw  and  more  or  less  muddy  water,  with  a  view  to 
causing  the  formation  of  gelatinous  aluminium  hydroxid,  which 
entangles  the  mud  and  some  bacteria  in  a  precipitate  that  will 
not  pass  the  sand  or  other  porous  media.  The  amount  of  alum 
required  varies  from  i  to  10  gr.  in  the  gallon,  according  to  the 
turbidity  of  the  water  and  the  amount  of  dissolved  carbonates 
with  which  to  react.  Using  judgment,  the  proportion  of  alum 
may  be  kept  within  the  limits  of  the  precipitation,  and  thus  no 
dissolved  alum  pass  into  the  filtered  water. 

Detection. — Having  incinerated  the  organic  matter  in  a  plati- 
num dish,  the  ash  should  be  treated  with  hydrochloric  acid, 
excess  of  acid  removed  by  heat,  a  few  drops  of  nitric  acid  added, 
and  a  final  solution  in  hydrochloric  acid  boiled  and  filtered. 
This  acid  solution  is  not  changed  by  potassium  ferrocyanid  or 
hydrogen  sulphid,  as  are  solutions  containing  the  heavy  metals. 
Its  hydroxid  is  precipitated  from  an  alkaline  solution  by  hydrogen 
sulphid,  or  from  a  neutral  solution  by  ammonium  sulphid.  With 
potassium  hydroxid  a  white  precipitate  falls,  redissolved  by 
excess,  whereas  an  excess  of  the  reagent  does  not  affect  the  pre- 
cipitate from  a  solution  of  the  alkaline  earths.  With  ammonium 
hydroxid  a  white  precipitate  is  formed  insoluble  in  excess. 

Logwood  Test. — The  most  convenient  test  for  alum  in  bread  is 
made  with  a  freshly  prepared  tincture  of  logwood.  This  tincture 
is  made  by  digesting  5  gm.  of  freshly  cut  logwood  chips  with 
100  c.c.  of  alcohol.  Having  diluted  5  c.c.  of  the  logwood  tincture 
with  90  c.c.  of  water  and  added  5  c.c.  of  saturated  solution  of 
ammonium  carbonate,  the  mixture  is  immediately  poured  over 
10  gm.  of  bread  in  a  glass  dish.  After  five  minutes  the  liquid  is 
poured  off,  the  bread  slightly  washed,  and  dried  at  ioo°C.  A 
lavender  or  dark-blue  color  denotes  that  alum  is  present.  Pure 
bread  is  at  first  reddish,  fading  to  a  yellow  or  light  brown. 

Delicacy. — This  test  yields  a  distinct  blue  with  0.02  per  cent, 
of  alum,  or  7  gr.  in  a  4-lb.  loaf. 

Fallacy. — Several  other  mineral  adulterants  produce  a  some- 
what similar  reaction. 

Alum  in  Drinking  Water. — When  excess  of  alum  is  used  in 
filtering  water  its  presence  may  be  detected  by  the  logwood  test 


256  THE    METALS 

as  follows:  To  the  suspected  water  add  fresh  tincture  of  log- 
wood, enough  to  give  a  decided  color;  now  add  a  solution  of 
ammonium  carbonate.  If  a  blue  precipitate  fall,  then  alum  is 
present  at  least  i  :  1000;  if  no  precipitate,  but  a  blue  color  per- 
sist for  an  hour,  then  alum  is  present  at  least  i  :  50,000.  If  before 
the  hour  be  out  the  color  be  brown  or  pink,  then  there  is  no 
alum. 

Alum  in  Baking  Powder. — A  small  quantity  of  the  suspected 
powder  is  burnt  to  an  ash,  which  is  then  treated  with  boiling 
water  and  filtered.  If  the  filtrate  yields  a  flocculent  precipitate 
when  treated  with  ammonium  chlorid,  then  alum  is  present  in  the 
sample. 


WATER  SUPPLY 

MINERAL  WATERS 

WHILE  natural  waters  usually  contain  mineral  constituents  in 
varying  proportions,  some  are  so  rich  in  dissolved  salts  and  gases 
as  to  have  a  marked  taste  and  a  medicinal  effect.  These  spring 
saline  waters  are  grouped  according  to  some  important  compo- 
nent, as  saline,  carbonated,  chalybeate,  alkaline,  sulphurous. 

Saline. — Among  these  may  be  named  Kissingen,  Saratoga, 
Seidlitz,  Hot  Springs  of  Arkansas.  They  contain  chlorids,  sul- 
phates, and  carbonates  of  sodium,  potassium,  lithium,  magnesium, 
and  calcium. 

Carbonated. — The  best  known  of  these  are  Apollinaris,  Sel- 
ters,  and  Old  Sweet  West  Virginia.  They  effervesce  with  the 
carbon  dioxid,  which  while  dissolved  enables  them  to  hold  in 
solution  carbonates  of  sodium,  magnesium,  and  calcium. 

Sulphurous. — Prominent  among  these  are  White  Sulphur, 
W.  Va.;  Sharon,  N.  Y.;  Blue  Lick,  Ky.  They  sparkle  with  the 
dissolved  gases,  carbon  dioxid  and  hydrogen  sulphid,  and  hold 
in  solution  chlorids,  sulphates,  and  carbonates  of  sodium,  potas- 
sium, magnesium,  calcium,  and  sometimes  iron. 

Alkaline. — Familiar  examples  are  seen  in  Gettysburg,  Pa.; 
Hot  Springs,  Va.;  Buffalo  Lithia,  Va.;  and  Vichy,  France.  They 
contain  a  large  amount  of  sodium  carbonate  and  lesser  amounts 
of  chlorids,  sulphates,  and  carbonates  of  sodium  and  other  metals. 

Chalybeate. — Among  well-known  iron  springs  may  be  men- 
tioned Cresson,  Pa.;  Rockbridge,  Va.;  Bath  Alum,  Va.  They 
owe  their  tonic  virtues  to  the  iron  sulphate,  carbonate,  and  oxid 
held  in  solution  by  the  dissolved  carbon  dioxid.  They  also  con- 
tain sodium,  magnesium,  and  aluminium  compounds. 


WATER    FOR    DOMESTIC    USE  257 

WATER  FOR  DOMESTIC  USE 

Water  of  absolute  chemical  purity  is  not  found  in  nature,  and 
probably  would  not  be  desirable  for  drinking  purposes.  Distilled 
water  is  not  palatable;  it  lacks  the  ions  to  which  we  have  grown 
accustomed  and  which  are  necessary  to  health.  The  natural 
supplies  that  are  preferred  instinctively  contain  a  moderate 
amount  of  mineral  matter  and  some  carbon  dioxid  in  solution. 
Water  that  is  hygienically  pure  is  of  the  first  importance  to  com- 
munities and  individuals.  It  must  be  palatable,  clear,  contain 
not  more  than  15  parts  of  harmless  minerals  in  100,000  of  water, 
with  no  lead  or  other  poisons,  and  be  wholly  free  from  the  specific 
bacteria  of  disease. 

Rain  water  is  the  primary  form  of  nature,  and  if  it  be  collected 
in  the  country  and  stored  in  well-made  cisterns,  is  wholesome. 
It  may  have  dissolved  from  the  air  traces  of  ammonia  and  other 
gases  and  in  the  city  it  may  wash  down  dust  particles,  some  of 
which  are  organic  and  bacterial,  though  in  most  cases  the  micro- 
organisms are  not  disease-producing.  Rain  water  is  only  rel- 
atively pure. 

Surface  Water. — Rain  water  falling  upon  the  earth  becomes 
in  part  surface  water,  flowing  and  remaining  above  ground.  The 
lie  of  the  land  causes  it  to  collect  in  ponds  or  lakes  or  to  drain 
away  in  creeks  and  rivers.  In  agricultural  watersheds  the  erosion 
by  the  water  increases  materially  the  organic  matter,  the  increase 
being  dissolved  from  decaying  vegetation.  The  mineral  addition, 
however,  is  very  small,  and  the  water  remains  almost  as  soft  as 
rain  water.  If  the  watershed  be  thickly  inhabited,  as  along  the 
banks  of  some  rivers,  it  may  remain  wholesome  as  long  as  it  is 
free  from  the  specific  bacteria  of  disease.  Such  a  water  is  liable 
at  any  time  to  be  contaminated  by  the  entrance  of  bacteria  from 
sewage  containing  excrement  from  cases  of  typhoid  fever,  dysen- 
tery, cholera,  or  diphtheria.  The  evidence  is  incontrovertible  that 
drinking  water  can  cause  these  diseases,  and  that  it  does  so, 
because  of  the  presence  of  the  peculiar  germs.  In  the  cholera 
epidemic  of  Hamburg,  Germany,  in  1893,  the  typhoid-fever  out- 
break of  Plymouth,  Pa.,  in  1883,  and  of  Ithaca,  N.  Y.,  in  1903, 
the  dejecta  of  a  single  patient  passing  into  the  water  supply  were 
sufficient  to  cause  an  enormous  amount  of  mischief. 

Ground=water  is  that  part  of  the  rainfall  which  sinks  through 
the  porous  earth  until  it  is  stopped  by  a  bed  of  clay  or  rock. 
The  water  then  moves  laterally  upon  this  impervious  stratum 
through  the  permeable  soil  toward  the  nearest  surface  water  at 
a  lower  level.  This  addition  by  diluting  a  river  lessens  the  pro- 
portion of  sewage  material  that  the  river  may  have  received. 
17 


258  THE    METALS 

Sometimes  it  comes  forth  again  as  a  natural  spring;  sometimes 
it  is  tapped  by  a  well.  On  its  way  through  the  porous  soil  it 
dissolves  out  the  soluble  minerals,  but  by  a  natural  nitration  such 
water  is  free  from  organic  matter  and  wholesome,  provided  it 
has  not  taken  up  too  much  mineral  salts  to  be  palatable.  Its 
organic  purity  is  due  to  the  fact  that  it  has  traversed  the  home 
of  the  non-pathogenic  bacteria  which  abide  in  the  surface  zone 
of  the  earth  and  form  a  gelatinous  layer.  Decaying  organic  matter, 
surface  water,  and  the  air  furnish  the  bacteria  with  their  food.  By 
the  time  the  water  has  descended  eight  or  ten  feet  it  has  been  so 
exhausted  of  organic  matter  that  it  no  longer  supports  the  life  of 
micro-organisms.  Ordinary  house  wells  are  sometimes  contam- 
inated and  become  foci  of  infection.  The  mode  of  access  of  the 
germs  to  a  well  may  be  by  communication  from  a  near  cesspit 
through  a  gravelly  stratum,  or  by  the  loss  of  the  natural  filtra- 
tion powers  of  the  soil  through  saturation  with  filth  resulting 
from  old  and  crowded  communities. 

The  pollution  of  domestic  wells  is  not  only  by  underground 
channels,  but  also  by  overflow  of  foul  surface  water  from  barns 
or  drains.  Deep  wells  in  rural  districts  give  wholesome  water 
if  properly  curbed  and  covered,  and  not  sunk  too  near  cesspits, 
drains,  and  stables. 

Hard  and  Soft  Waters. — As  a  rule,  surface  waters  are  said 
to  be  soft  and  well  waters  of  a  limestone  region  hard.  Hard 
waters  are  so  named  because  in  rinsing  the  hands,  after  soaping 
them,  the  water  does  not  clean  away  from  the  pores  that  which 
gave  a  hard  feeling  left  after  washing.  This  disagreeable 
residue  is  made  up  of  the  insoluble  curds  of  calcium  and  mag- 
nesium oleate,  resulting  from  a  reaction  between  the  sodium 
oleate  of  soap  and  the  salts  of  magnesium  and  calcium  in  the 
water.  Until  these  salts  are  all  precipitated  as  oleate  the  water 
and  the  soap  are  useless  detergents,  for  only  then  do  they  form 
a  lather.  By  boiling  a  hard  water  carbon  dioxid  is  driven  off 
and  the  soluble  calcium  and  magnesium  bicarbonates  converted 
into  insoluble  carbonates,  which  are  precipitated.  This  process 
so/tens  the  water  by  removal  of  the  temporary  hardness.  The 
salts  remaining  in  solution,  such  as  the  sulphates  and  chlorids, 
after  boiling  give  to  the  water  its  permanent  hardness.  In  laun- 
dries it  is  customary  to  soften  water  and  add  to  its  cleansing  powers 
by  the  addition  of  concentrated  lye,  sodium  hydroxid;  or  pearlash, 
potassium  carbonate.  These  precipitate  the  calcium  and  mag- 
nesium salts  and  give  to  the  water  greater  penetrating  and  dis- 
solving power  over  grease,  epithelial  debris,  and  other  dirt. 


DRINKING    WATER 


259 


DRINKING  WATER 

Sand  Filters. — Artificial  improvement  of  the  house  sup- 
ply is  commonly  obtained  by  filtering  the  water  through  sand 
in  domestic  filters,  aided  by  the  precipitation  of  suspended  matter 
with  alum,  as  described  on  p.  255.  This  yields  a  specimen  much 
improved  in  appearance  and  in  taste,  but  not  with  certainty 
deprived  of  the  germs  of  communicable  disease  (p.  260). 

Artificial  improvement  of  a  town  supply  is  best  done  after 
the  methods  of  nature.  To  obtain  water  like  that  of  springs 
and  deep  wells  for  a  town  or  city  it  is  slowly  filtered  through 
sand.  In  this  way  it  is  purified  precisely  as  is  rainfall  on  passing 
through  porous  earth.  Beds  of  sand  are  constructed  and  thoroughly 
underdrained.  The  water  is  permitted  to  spread  over  the  sur- 
face and  percolate  through  the  sand.  In  a  short  while  a  bac- 
terial jelly  forms  on  the  surface  which  performs  the  same  work 
of  purification  as  is  done  for  spring  and  well  waters  by  the  nitri- 


FIG.  6 1.— Cross-section  of  filter  plant  (Jour.  A.  M.  A.). 

fying  bacteria  that  crowd  the  superficial  layers  of  the  earth.  The 
high  efficiency  of  slow-working  sand  filters  has  been  demonstrated 
beyond  question.  Of  many  examples,  that  of  the  neighboring 
cities,  Altona  and  Hamburg,  in  Germany,  is  most  celebrated. 

These  two  cities  are  both  dependent  upon  the  river  Elbe  for 
their  water  supply,  but  the  Hamburg  intake  is  above  the  city, 
while  that  for  Altona  is  below  Hamburg,  after  it  has  received  the 
sewage  of  800,000  persons.  In  1893,  in  Hamburg,  the  deaths 
from  cholera  amounted  to  1250  per  100,000,  and  in  Altona  to 
but  22  per  100,000  of  the  population.  The  epidemic  spread  from 
the  Hamburg  side  up  to  the  boundary  line  between  the  two  cities 
and  there  stopped.  In  one  street  which  separates  them  the  Ham- 
burg side  was  stricken  with  cholera,  whilst  that  belonging  to  Altona 
remained  free.  In  those  houses  supplied  with  the  Hamburg  water 
cholera  was  rife,  while  in  those  furnished  with  the  Altona  water 
not  one  case  occurred.  The  Hamburg  water,  to  start  with,  was 
comparitively  pure  when  contrasted  with  the  dilute  sewage  drawn 


260  THE    METALS 

from  the  Elbe  by  Altona,  but,  in  the  latter  case,  the  water  was 
submitted  to  filtration  through  sand,  while  in  Hamburg  the  water 
was  in  its  raw  condition  as  drawn  from  the  river. 

Construction  of  a  Town  Filter. — The  unit  filter  is  a  water-tight 
masonry  reservoir  with  an  area  of  one-half  to  two  acres.  On  the 
floor  of  the  reservoir  are  perforated  underdrains,  upon  which  are 
placed  layers  of  coke  or  crushed  stone  and  gravel  of  increasing 
fineness,  and  last  of  all  a  bed  of  sand  2  to  4  feet  deep,  which  is 
to  embody  the  bacterial  jelly.  It  is  highly  desirable  to  have  a 
settling  basin,  through  which  the  raw  water  must  pass  before  it  is 
permitted  to  flow  upon  the  filter,  after  leaving  its  mud  behind. 

Storage. — The  method  of  nature  in  purifying  surjace  waters 
which  do  not  penetrate  the  porous  soil  is  quiescence,  as  in  the 
case  of  lakes  and  ponds.  A  running  stream  has  very  little  power 
of  self-improvement.  A  public  supply  may  be  drawn  from  a 
creek  or  river  and  stored  in  reservoirs,  leaving  it  to  the  ripening 
effects  of  time.  The  longer  it  is  stored,  the  greater  the  opportunity 
afforded  the  nitrifying  bacteria  to  destroy  the  organic  matter 
necessary  for  the  sustenance  of  the  germs  of  disease.  The  total 
number  of  bacteria  in  a  surface  water  is  much  reduced  by  storage 
for  a  while  and  by  slow  filtration  through  sand  after.  The  best 
results  in  purifying  the  water  and  reducing  the  mortality  are 
obtained  by  using  both  storage  and  filtration. 

In  case  it  is  impossible  to  have  the  water  supply  treated  as 
indicated  above,  decided  improvement  can  be  had  by  installing 
small  filters  in  houses.  These  make  the  water  clear,  and  if  prop- 
erly constructed  and  cared  for,  lessen  the  number  of  bacteria.  If 
neglected  they  become  breeding  grounds  for  bacteria  and  fail  to 
be  of  benefit.  The  only  filters  that  are  recommended  are  those 
which  force  the  water  through  porcelain,  such  as  the  Pasteur  and 
the  Berkfeld.  The  porcelain  tubes  should  be  cleaned  every  week 
or  so,  and  boiled  in  water  for  half  an  hour.  It  is  well  to  bake 
them  in  a  pottery  furnace  fire  every  six  months. 

When  the  drinking  water  of  a  household  comes  under  sus- 
picion it  should  be  condemned  as  raw  water,  since  it  can  be  made 
wholesome  by  boiling  only.  Most  of  the  bacteria  are  killed  at 
the  boiling-point,  but  some  survive  unless  the  boiling  be  con- 
tinued for  twenty  minutes.  When  thus  sterilized  the  water  may 
be  recharged  with  air  by  a  bellows  or  it  may  be  poured  from 
pitcher  to  pitcher.  It  may  also  be  drunk  as  a  weak  infusion  of 
tea  or  lemonade  to  make  it  palatable. 

Examination  of  Drinking  Water.— While  chemical  anal- 
ysis is  not  without  some  importance,  especially  if  no  other  knowl- 
edge be  obtainable,  the  most  significant  facts  about  a  water  supply 
are  often  obtained  by  an  engineer's  inspection  of  the  watershed 


DRINKING    WATER  261 

and  the  surroundings  of  the  reservoir.  Every  shallow  well  in 
a  densely  populated  district  is  unsafe  and  should  be  condemned. 
No  chemical  or  bacterial  examination  is  required  to  determine  the 
fact  of  sewage  contamination  when  drains  are  seen  to  enter  the 
stream.  Any  water  supply  which  has  once  received  polluted 
material  may,  under  like  conditions,  be  again  contaminated.  If 
it  be  under  suspicion,  special  survey  of  the  territory  will  often 
point  out  the  particular  source  of  mischief. 

The  constitution  of  ground  and  surface  waters  is  different  even 
when  both  may  be  wholesome.  The  organic  matter  revealed  by 
chemical  and  bacterial  tests  applied  to  a  surface  water  does  not 
necessarily  condemn  it,  but  would  be  significant  of  pollution  if 
found  in  a  well  water.  Correct  interpretation  of  the  analysis 
depends  upon  a  knowledge  of  the  source  of  the  sample  as  well  as 
the  mode  of  collection  and  transportation. 

Biologic  Test. — Reliance  is  fairly  well  placed  upon  this  test 
properly  performed  by  experts  trained  in  the  procedures  of  the 
bacteriologic  laboratory  which  cannot  be  adequately  presented 
in  this  work.  An  approved  method  is  based  upon  the  fact  that, 
though  there  may  not  be  present  in  the  specimen  the  typhoid 
bacillus  or  other  pathogenic  bacteria,  there  is  reason  to  condemn 
the  water  when  the  intestinal  organism  Bacillus  coli  communis,  by 
its  presence,  witnesses  to  sewage  contamination.  Absence  of  this 
bacillus,  after  careful  search,  would  indicate  that  there  is  no  direct 
access  of  animal  or  human  feces  to  the  well  or  other  source  of 
water  supply. 

When  sewage  is  diluted  with  distilled  water,  and  the  mixture 
tested,  it  has  been  found  that  the  biologic  test  will  show  the  presence 
of  the  Bacillus  coli,  when  the  proportion  of  sewage  was  so  small 
that  chemical  analysis  revealed  nothing  suspicious.  It  must  be 
recognized  that  proper  bacteriologic  methods  surpass  the  chemical 
both  in  delicacy  and  in  indicating  sewage  pollution.  When  such 
evidence  is  not  at  hand  resort  may  be  had  to  the  following  chemical 
tests. 

The  value  of  these  quantitative  results  depends  mainly  upon 
a  comparison  with  previous  analyses  made  of  the  same  water  under 
normal  conditions. 

The  total  solids  are  determined  by  weighing  a  platinum  or 
nickel  evaporating  dish,  filling  it  with  i  L.  of  the  water,  and 
evaporating  over  a  water-bath,  drying  at  110°  C.  (230°  F.)  or 
over  H2SO4,  and  weighing  dish  and  residue.  On  heating  to 
redness,  charring  of  the  residue  would  indicate  organic  matter. 
The  total  solids  should  not  exceed  500  mg.  per  liter. 

Chlorids  in  themselves  are  not  dangerous,  but  are  significant 
because  the  sodium  chlorid  of  wells  and  rivers  is  mainly  derived 


262  THE    METALS 

from  urine  and  other  domestic  waste.  A  sudden  increase  in  the 
proportion  of  chlorids  points  to  an  access  of  sewage.  In  titrating 
for  chlorids  100  c.c.  of  the  suspected  water  is  put  in  a  beaker,  made 
neutral  or  alkaline  with  a  drop  of  sodium  hydrate,  and  colored  with 
neutral  potassium  chromate.  Silver  nitrate  solution  is  run  in  from 
a  buret  until  a  red  color  persists.  The  test  solution  contains  AgNO3, 
4.79  gm.  per  liter,  and  each  cubic  centi meter  =  0.01  gm.  of  chlorin 
per  liter  (0.7  gr.  per  gallon).  In  an  emergency  a  water  should  be 
condemned  which  shows  more  than  .03  gm.  per  liter  (3  gr.  per 
gallon),  or  which  reveals  marked  increase  from  its  normal  amount, 
as  determined  by  previous  examinations. 

Organic  Matter  by  Permanganate  Process.— The  presence 
of  organic  contamination  is  revealed  by  the  change  of  color  in 
a  pink  solution  of  potassium  permanganate.  It  loses  oxygen  and 
is  reduced  to  a  faintly  brownish  product. 

Experiment  i. — Put  in  a  beaker  100  c.c.  of  pure  distilled  water, 
add  5  c.c.  of  dilute  sulphuric  acid,  boil  on  wire  gauze  and  add  5 
drops  of  dilute  permanganate  solution  (30  mg.  in  100  c.c.)  and  boil 
5  minutes.  There  is  no  fading  of  color.  Now  add  urine  or  egg 
albumin  and  boil  again;  the  color  is  discharged.  The  number  of 
cubic  centimeters  of  a  standard  pink  solution  required  to  overcome 
this  fading  of  color  is  a  measure  of  organic  impurity. 

Ammonia  is  a  characteristic  product  of  the  decomposition  of 
nitrogenous  organic  matter,  such  as  urea,  and  its  presence  in 
amounts  in  excess  of  0.05  mg.  per  liter  is  a  danger  signal  indicative 
of  sewage  pollution.  The  jree  ammonia  is  obtained  by  distilling 
the  suspected  water  after  adding  to  it  some  sodium  carbonate, 
leaving  a  remainder  in  the  flask  for  the  next  process. 

Some  of  the  nitrogenous  matter  of  animal  origin  may  be  present 
unchanged,  and  to  obtain  proof  of  this  it  is  necessary  to  break  it 
up  and  separate  the  nitrogen  as  albuminoid  ammonia.  This  is 
done  by  distilling  the  remainder  after  subjecting  it  to  the  action  of 
an  alkaline  permanganate  solution.  Pure  drinking  water  does 
not  yield  more  than  o.i  mg.  per  liter. 

The  determination  of  ammonia  In  the  distillate  is  made  by  the 
comparison  of  the  yellow  color  produced  by  Nessler's  solution,1 
when  measured  amounts  are  added  to  the  water,  and  to  a  solution 
of  ammonium  chlorid  of  known  strength.  The  elaborate  part 
of  this  operation  is  the  distillation.  It  may  be  dispensed  with  if 
free  ammonia  only  is  to  be  determined,  the  Nesslerizing  being 
applied  to  the  original  sample  after  precipitating  the  calcium  salts 

1This  is  an  alkaline  mercuric  potassium  iodid  solution  made  by  dissolving 
5  gm.  of  potassium  iodid  in  hot  water  and  adding  a  solution  of  2.5  gm.  of  mercuric 
chlorid  in  10  c.c.  of  hot  water.  The  red  mixture  clears  when  there  is  added 
16  gm.  of  potassium  hydroxid  in  40  c.c.  of  water  and  the  whole  diluted  to  make 


ANTIMONY  291 

Arsenic  in  the  Soil. — Some  soils  naturally  contain  arsenic  in  an 
insoluble  iron  compound.  Headden  has  found  that  other  virgin 
soils  yield  traces  to  water  as  a  solvent. 

After  the  use  of  superphosphate  as  manure,  arsenic  may  be 
imparted  by  the  impure  sulphuric  acid  used  in  its  manufacture. 
Paris  green,  sprinkled  to  kill  bugs  on  the  plants  of  potato,  cabbage, 
or  beets,  adds  some  to  the  soil.  Lead  arsenate  and  calcium  arsenite 
as  insecticides  sprayed  on  orchard  trees  furnish  a  soluble  fraction 
to  the  ground  and  the  rootlets  absorb  it.  In  a  number  of  years 
the  soil  of  sprayed  orchards  is  10  to  28  times  stronger  in  arsenic 
than  was  the  virgin  soil.  Potatoes,  turnips,  beets,  oats,  alfalfa, 
apples,  pears,  and  the  flesh  of  cattle  grown  on  such  a  soil  have  all 
given  signs  of  arsenic. 

Persons  eating  freely  of  apples  from  sprayed  trees  secrete  urine 
showing  arsenic.  From  such  food-plants  and  meats  the  human 
body  may  get  the  trace  often  found  postmortem,  even  if  the  ar- 
senic-enriched soil  does  not  supply  it  to  the  corpse  after  burial.  In 
cities  it  is  the  general  custom  for  undertakers  to  embalm  corpses 
by  pumping  a  solution  of  sodium  arsenate  through  the  nostrils 
into  the  stomach,  trusting  to  the  high  diffusibility  of  that  salt 
to  carry  it  throughout  the  body.  Experiments  show  that  in 
twelve  days  the  arsenic  may  permeate  the  entire  body,  reaching 
the  brain.  It  is  possible  that  this  same  compound  would  event- 
ually pervade  the  soil  of  the  cemetery  contiguous  to  a  buried  corpse. 

ANTIMONY   (Stibium) 

Symbol,  Sb.     Atomic  weight,  120. 

Antimony  is  a  brilliant  gray-white  solid  with  a  crystalline, 
metallic  fracture,  tasteless  and  odorless.  When  heated  it  volatil- 
izes; at  a  higher  temperature  it  burns  to  white  fumes  of  antimony 
trioxid,  Sb2O3.  It  is  used  as  an  alloy  in  type  metal,  Britannia 
metal,  brass,  and  bell  metal.  Though  the  metal  may  not  be 
poisonous,  its  salts  are. 

While  poisoning  from  antimony  was  quite  common  in  the  Middle 
Ages,  in  our  times  it  is  comparatively  rare.  Cases  have  been 
reported  from  inhalation,  probably  of  the  trioxid,  in  certain  indus- 
tries. Lozenges  containing  the  same  preparation  were  the  cause 
of  poisoning  in  another  case.  In  modern  toxicology  but  two 
forms  figure  to  any  extent,  the  trichlorid  and  tartar  emetic. 

Sulphurated  antimony  (Kermes  mineral),  a  mixture  of 
Sb2S3  and  Sb2O3,  is  employed  in  vulcanizing  rubber.  The  India 
rubber  connections  of  the  Marsh  apparatus  might  thus  contribute 
a  trace  of  antimony,  unless  care  be  taken  to  avoid  the  use  of 
fittings  made  with  this  preparation.  It  is  a  constituent  of  the 
medical  preparation,  Plummer's  pill. 


292  THE    METALS 

Antimony  trioxid,  Sb2O3,  occurs  as  a  white  powder  of  basic 
properties,  although,  because  it  corresponds  to  As2O3,  it  is  some- 
times erroneously  called  antimonious  acid.  It  dissolves  in  alkalies; 
hence,  undergoes  some  change  and  possibly  forms  an  anion,  as  in 
the  formula  H*,  (SbO2);  thus,  sodium  meta-antimoniate  is  NaSbO2. 
Dose:  i  to  3  gr.  (0.06-0.2  gm.).  It  is  a  component  of  James1 
powder,  which  contains  calcium  phosphate  with  antimony  trioxid. 

Antimony  terhydrid  (SbH3)  (antimoniureted  hydrogen)  is 
a  colorless,  odorless  gas,  corresponding  to  arsenic  terhydrid.  It 
is  given  off  when  zinc  and  sulphuric  acid  react  in  the  presence  of 
an  antimony  salt.  It  differs  from  arsenic  terhydrid  in  having  no 
garlicky  odor  and  in  being  less  poisonous. 

Antimony  trichlorid  (SbCl3)  (butter  of  antimony)  occurs  as 
a  soft  solid.  A  strong  solution  of  the  chlorid  in  hydrochloric  acid 
is  employed  in  the  arts  as  a  bronzing  liquid  and  in  farriery.  It 
crystallizes  white  and  transparent.  Added  to  water,  a  whitish 
precipitate  falls,  of  antimony}  chlorid,  SbOCl. 

The  records  of  8  cases  of  poisoning  show  that  in  the  4  fatal 
ones  the  dose  was  2  oz.,  while  2  that  recovered  took  i  oz.  each. 
A  woman  of  forty  years  died  in  less  than  two  hours;  in  her  stomach 
were  found  8  gr.  of  antimony  and  o.i  gr.  of  arsenic. 

Tartar  Emetic  (KSbOC4H4O6)  (Tartarated  Antimony,  Stib- 
iated  Tartar,  Antimonii  et  Potassii  Tartras). — This  is  a  white 
crystalline  powder  with  an  acrid,  disagreeable,  metallic  taste.  It 
is  made  by  the  action  of  a  boiling  solution  of  cream  of  tartar 
upon  antimony  trioxid.  Dose:  J  to  3  gr.  (0.008-0.2  gm.).  It 
may  be  regarded  as  acid  tartrate  of  potassium,  KHC4H4O6,  the 
hydrogen  of  which  is  replaced  by  the  radical  antimonyl  SbO.  It 
has  been  dispensed  by  mistake  for  cream  of  tartar  and  for  tartaric 
acid.  It  is  soluble  in  cold  water,  more  readily  in  hot  water,  but 
insoluble  in  alcohol.  Wine  is  used  as  a  vehicle  in  vinum  anti- 
monii  (0.4  per  cent,  tartar  emetic),  the  water  of  the  wine  acting 
as  a  solvent  and  the  alcohol  checking  the  formation  of  the  moulds, 
to  which  a  simple  aqueous  solution  is  liable.  It  is  present  in 
syrupus  scillce  compositus  ("Hive  Syrup"),  dose:  15  to  60  tlft 
(1-3  c.c.),  and  in  unguentum  antimonii. 

Symptoms. — There  is  a  close  resemblance  between  the  symp- 
toms caused  by  antimony  and  those  produced  by  arsenic.  While 
it  occasionally  happens  that  large  doses  (200  gr.  of  tartar  emetic) 
do  not  cause  vomiting,  as  a  rule,  nausea,  retching,  and  vomiting 
come  on  within  half  an  hour  and  continue  as  conspicuous  features 
of  the  clinical  picture,  which  may  be  sketched  as  follows:  In  a 
few  seconds  there  is  an  acrid  and  metallic  taste,  followed  by  a  sense 
of  constriction  in  the  throat  and  pain  in  the  stomach;  frequent  and 
profuse  vomiting,  sometimes  of  bloody  material;  diarrhea  with 


ANTIMONY  293 

watery  discharges,  sometimes  involuntary,  sometimes  attended' 
with  tenesmus;  fainting  attacks  and  depression,  characterized  by 
a  feeble  and  frequent  pulse  and  profuse  sweating;  spasmodic  con- 
traction of  the  arms,  fingers,  and  legs.  In  very  grave  cases  the 
urine  may  be  wholly  suppressed,  the  temperature  subnormal,  the 
skin  cyanotic,  and  death  be  ushered  in  by  delirium,  convulsions, 
and  coma.  There  are  exceptional  cases  in  which  no  vomiting 
occurs  for  an  hour,  and  others  in  which  drowsiness  and  power- 
lessness  come  on  early,  are  succeeded  by  tetanic  spasms,  the  other 
symptoms  also  being  present,  and  later,  persistent  enteritis  with 
loss  of  the  hair  on  recovery.  In  i  case  coma  was  the  prominent 
symptom,  with  death  on  the  sixth  day. 

When  antimony  chlorid  has  been  taken,  to  the  symptoms  of 
antimony-poisoning  are  added  those  of  the  strongly  acid  liquid, 
which  causes  corrosion  of  the  stomach. 

Chronic  Poisoning. — In  most  cases  of  homicidal  poisoning 
from  antimony,  tartar  emetic  has  been  given  in  divided  doses  to 
invalids.  The  effects  of  the  poison  are  thus  mistaken  for  symp- 
toms of  some  low  fever  or  chronic  disease,  and  the  crime  may  go 
undetected.  The  patient  is  seen  to  suffer  from  "  sickness," 
loathing  for  food,  which,  if  taken,  is  not  retained,  diarrhea,  mus- 
cular cramps,  physical  and  nervous  prostration,  weak  pulse,  and 
cold  sweats. 

Fatal  Dose  of  Tartar  Emetic. — The  smallest  dose  that  has 
proved  fatal  to  a  child  is  }  gr.  (48.5  mg.).  A  healthy  woman,  aged 
twenty-five  years,  took  the  maximum  medicinal  dose,  ij  gr. 
(97.2  mg.),  without  effect,  but  a  similar  dose  twenty-four  hours 
later  excited  violent  purging  and  vomiting,  with  death  in  thirty- 
six  hours.  Such  cases  cannot  be  considered  as  fixing  the  danger 
limit.  Ten  grains  at  one  time  would  be  a  dangerous  dose,  but 
the  same  amount  in  broken  doses  would  be  still  more  so. 

Recovery  has  followed  a  dose  of  170  gr.  As  a  rule,  prompt 
emesis  follows  the  administration  of  a  large  dose,  and  the  effects 
are  mainly  local  and  not  serious.  If  the  poison  be  retained  and 
absorbed,  the  vomiting  center  is  indirectly  involved,  and  purging, 
with  extreme  depression,  becomes  the  prominent  symptom.  At 
one  time  it  was  considered  good  practice  in  acute  inflammatory 
diseases  to  give  doses  of  i  gr.  at  intervals,  to  establish  "  tolerance." 
By  the  second  day  some  patients  would  tolerate  the  drug  without 
vomiting  and  purging,  and  " heroic"  doses  of  5  gr.  each  could  be 
given  without  inducing  these  effects.  As  much  as  60  gr.  daily 
have  been  given  in  this  way  without  disturbance  of  the  stomach. 
The  effects  in  such  cases  are  mainly  those  of  depression  of  the 
heart  action  and  of  the  nervous  system. 

Fatal  Period. — A  fatal  result  has  occurred  in  an  adult  in  seven 


294  THE    METALS 

hours.  In  an  exceptional  case  death  occurred  in  a  child  in  three- 
quarters  of  an  hour.  The  fatal  event  may  be  delayed  for  several 
days,  the  average  duration  of  life  being  twenty-four  hours. 

Treatment. — As  a  rule,  the  free  vomiting  induced  by  the  tartar 
emetic  is  sufficient  to  evacuate  the  stomach.  In  the  rare  cases 
where  it  does  not  occur,  other  emetics  should  be  given,  such  as 
sulphate  of  zinc  or  mustard  and  water;  or  the  stomach  may  be 
washed  out  with  a  mixture  of  hot  water  with  the  antidote,  tannic 
acid;  or  a  decoction  of  green  tea  or  of  some  vegetable  astringent 
—all  these  forming  the  insoluble  tannate  of  antimony.  When 
the  stomach  has  been  emptied  morphin  should  be  given  hypo- 
dermically  to  relieve  pain,  and  the  irritable  stomach  and  bowels 
treated  with  suitable  remedies.  The  depression  of  the  heart  must 
be  counteracted  with  stimulants,  aided  by  dry  heat  or  mustard  to 
the  epigastrium  and  the  extremities. 

If  antimony  chlorid  has  been  taken,  the  corrosive  action  on  the 
stomach  would  cause  a  condition  which  would  be  aggravated  by 
the  mechanical  irritation  of  the  stomach-tube. 

Postmortem  Appearances. — In  i  case  of  acute  tartar-emetic 
poisoning  the  autopsy  revealed  nothing,  although  the  poison  was 
found  in  the  viscera,  urine,  blood,  and  intestinal  contents.  Such 
a  result  is  quite  exceptional,  most  cases  showing  redness,  swell- 
ing, ecchymotic  patches,  and  perhaps  ulceration  in  the  gastro- 
intestinal mucous  membrane.  Sometimes  the  changes  in  the  gullet 
and  pharynx  are  profound,  as  in  a  case  in  which  there  was  de- 
structive ulceration  of  the  membrane  of  the  epiglottis  and  of  the 
adjacent  parts,  exposing  the  muscular  fibers  of  the  pharynx.  In 
a  case  of  poisoning  from  the  corrosive  antimony  chlorid,  after 
vomiting  without  blood,  the  patient  went  into  collapse  and  died  in 
two  hours.  The  gastric  membrane  was  almost  black  from  con- 
gestion. 

In  cases  of  chronic  poisoning  it  is  usual  to  find  inflammation 
of  the  kidneys  and  liver. 

When  heated  in  a  test-tube  tartar  emetic  chars,  and  later  gives 
an  amorphous  sublimate  of  Sb2O3. 

Tests. — Hydrogen  Sulphid. — A  stream  of  this  gas  will  precipi- 
tate orange-red  antimony  trisulphid,  Sb2S3,  when  passed  through 
any  antimonial  aqueous  solution  acidified  with  hydrochloric  acid 
(Plate  2,  No.  5).  This  orange  precipitate  is  insoluble  in  ammo- 
nium hydroxid,  but  dissolves  in  the  fixed  alkalis,  in  ammonium 
sulphid,  and  in  strong  hydrochloric  acid,  especially  when  heated. 
A  very  characteristic  reaction  is  obtained  when  this  hydrochloric 
acid  solution  (after  boiling  to  expel  all  trace  of  hydrogen  sulphid) 
is  diluted  with  excess  of  water.  A  white  precipitate  of  antimony 
oxychlorid  falls,  which  is  soluble  in  tartaric  acid. 


ANTIMONY  295 

Fallacies. — While  this  test  is  quite  certain  in  simple  solution, 
it  may  give  a  doubtful  result  in  the  presence  of  colored  organic 
materials.  These  should  be  entirely  destroyed  to  give  a  satis- 
factory verdict. 

Delicacy. — A  definite  reaction  can  be  obtained  with  TFOTJT  of 
a  grain  of  antimony  trioxid  in  5  gr.  of  solution. 

Reinsch's  Test.— The  method  of  performing  this  test  has  been 
described  in  another  place  (p.  277).  If  any  precipitate  form, 
when  the  suspected  solution  is  acidified  with  hydrochloric  acid, 
more  acid  must  be  added  until  the  oxychlorid  is  redissolved.  On 
boiling  in  it  a  strip  of  bright,  pure  copper-foil  a  film  of  metallic 
antimony  will  appear.  If  the  amount  be  small,  the  film  is  violet. 
A  larger  quantity  will  give  a  surface  like  tarnished  zinc,  and,  if 
abundant,  a  black  amorphous  layer. 

Fallacies. — Arsenic,  mercury,  and  some  other  metals  make 
similar  deposits.  To  distinguish  the  nature  of  the  metallic  films 
the  copper  strip  must  be  washed  in  water,  alcohol,  and  ether, 
dried,  coiled,  and  heated  in  a  glass  tube  open  at  both  ends.  Under 
this  treatment  antimony  yields  a  white  sublimate  of  antimony  tri- 
oxid which  is  usually  amorphous,  although  sometimes  showing 
crystals;  arsenic  gives  a  sublimate  of  octahedral  crystals;  mer- 
cury a  sublimate  of  shining  metallic  globules;  and  other  metals, 
as  a  rule,  produce  no  sublimate.  The  antimony  trioxid  may  be 
dissolved  in  weak  tartaric  acid  and  an  orange-red  precipitate  be 
obtained  by  passing  hydrogen  sulphid  after  acidification  with 
hydrochloric  acid.  Again,  the  film  of  antimony  on  copper  may 
be  identified  by  boiling  it  in  a  weak  solution  of  potassium  hydroxid, 
removing  the  strip  at  intervals  to  expose  it  to  the  air.  If  the 
solution  of  antimony  thus  made  is  acidified  with  hydrochloric 
acid,  it  will  yield  an  orange-red  precipitate  with  hydrogen  sulphid. 

Delicacy. — A  distinct  violet-colored  deposit  on  the  copper  can 
be  obtained  from  i  gr.  of  a  solution  containing  -girrfrrr  gr-  °f  tartar 
emetic,  or  -^tinr  gr.  of  antimony  trioxid. 

Marsh's  Test.— In  the  section  on  Arsenic  (p.  279)  details  are 
given  for  performing  this  test.  If  antimony  be  present  the  gas- 
eous terhydrid  will  be  formed  which  has  not  the  onion-like  odor 
of  arsenic  terhydrid.  Its  flame  produces  a  black  spot  on  cold 
porcelain,  while  a  metallic  mirror  forms  in  the  delivery  tube  if 
that  be  heated  by  Berzelius'  method.  These  may  be  mistaken 
for  the  similar  deposits  made  by  arsenic.  When  treated  with 
solution  of  chlorinated  lime  or  chlorinated  soda  the  antimony 
deposit  is  insoluble,  while  arsenic  dissolves.  Yellow  ammonium 
sulphid  dissolves  both,  but  on  evaporation  the  solution  of  anti- 
mony sulphid  leaves  an  orange-red  spot  soluble  in  strong  hydro- 
chloric acid,  but  insoluble  in  ammonia.  The  corresponding 


296  THE    METALS 

arsenic  sulphid  is  yellow,  insoluble  in  hydrochloric  acid,  but 
soluble  in  ammonia. 

If  the  gas,  instead  of  being  burned  or  decomposed  by  heat  as 
above,  be  passed  into  solution  of  silver  nitrate,  there  is  a  black 
deposit  of  silver  antimonid,  Ag3Sb.  If  arsenic  be  also  present,  it 
remains  in  solution  and,  by  nitration,  we  can  separate  the  two. 
The  nitrate  can  be  tested  for  arsenic.  The  antimony  in  the  pre- 
cipitate may  be  separated  from  the  silver  by  dissolving  in  boiling, 
weak  hydrochloric  acid.  When  filtered  again  and  treated  with 
hydrogen  sulphid  the  filtrate  gives  orange-red  antimony  sulphid. 

Delicacy. — With  a  small  apparatus  spots  on  porcelain  are 
obtained  from  50  gr.  of  a  fluid  containing  -^  gr.  of  antimony 
trioxid,  while  a  good  deposit  in  the  heated  tube  is  yielded  by  the 
same  amount  of  fluid  containing  T^  gr-  of  antimony  trioxid. 

The  silver  nitrate  test  gives  a  still  more  delicate  reaction,  and 
can  be  obtained  with  only  a  few  drops  of  the  test  solution,  a  satis- 
factory deposit  of  silver  antimonid  forming  when  there  is  present 
only  g-oW gr-  of  tartar  emetic,  equal  to  20000  gr.  of  antimony  trioxid. 

Zinc  Test. — The  suspected  liquid  is  put  into  a  platinum  dish 
and  acidified  with  hydrochloric  acid.  On  immersing  a  slip  of 
pure  zinc  the  antimony,  but  not  arsenic,  is  at  once  deposited  on 
the  platinum  as  a  black  stain,  which  can  be  removed  later  by 
nitric  acid  or  by  simple  heat.  The  true  nature  of  this  stain  is 
revealed  by  wetting  it  with  nitric  acid,  drying  at  a  gentle  heat, 
and  touching  with  a  drop  of  dilute  ammonium  sulphid,  when  an 
orange-red  color  will  be  produced,  due  to  the  formation  of  anti- 
mony trisulphid. 

Delicacy. — This  test  is  very  delicate.  In  two  minutes  a  brown 
stain  will  appear  when  the  solution  holds  but  10000  gr-  of  anti- 
mony, a  definite  reaction  showing  in  a  quarter  of  an  hour  when 
the  amount  is  only  -^innro'- 

Tin  Test. — If  an  antimony  solution  be  acidulated  with  iV  part 
hydrochloric  acid  and  a  slip  of  pure  tinfoil  is  immersed  in  it,  the 
foil  turns  black  from  a  deposit  of  metallic  antimony. 

Detection. — In  Vomited  Matters  and  Urine. — Owing  to  the 
prompt  action  of  tartar  emetic,  the  stomach  and  bowels  are  usually 
quickly  evacuated  of  the  poison.  A  large  part  of  that  which 
is  absorbed  into  the  general  circulation  is  rapidly  eliminated 
by  the  kidneys,  and  hence  the  proportion  stored  in  the  viscera  is 
relatively  small.  In  cases  of  suspected  chronic  poisoning  the 
vomited  matters,  the  liquid  feces,  the  urine,  or  medicinal  mixtures 
should  be  subjected  to  analysis.  For  this  purpose  the  material 
is  acidified  with  hydrochloric  acid,  and  the  zinc  test  or  Reinsch's 
test  applied.  These  respond  even  in  the  presence  of  organic 
matter.  To  another  portion  of  the  material,  acidified  with  hydro- 


ANTIMONY  297 

chloric  acid,  tartaric  acid  is  added;  it  is  heated  on  a  water-bath 
for  half  an  hour,  strained,  filtered,  and  the  filtrate  treated  with 
a  stream  of  hydrogen  sulphid  for  several  hours.  The  precipitate, 
which  may  contain  the  sulphids  of  certain  other  metals  and  free 
sulphur,  should  be  treated  with  strong  hydrochloric  acid  and 
boiled  as  long  as  hydrogen  sulphid  fumes  escape.  The  filtered 
solution  may  be  tested  with  Reinsch's  test,  the  zinc  test,  or  Marsh's 
test,  collecting  the  antimony  in  silver  nitrate  solution.  In  testing 
the  urine  the  total  quantity  for  several  days  should  be  evaporated 
to  a  small  bulk  before  being  operated  on. 

Separation  from  the  Tissues. — From  the  solid  viscera  most  of 
the  antimony  can  be  extracted  by  mincing  a  portion  and  boiling 
it  for  an  hour  in  water,  5  parts,  acidified  with  hydrochloric  acid, 
i  part.  The  strained  and  filtered  solution  may  be  tested  by 
Reinsch's  or  the  zinc  test. 

Quantitative  Determination.— If  it  be  desired  to  calculate 
the  total  amount  of  antimony,  it  is  best  to  use  the  process  for 
destruction  of  organic  matter  by  hydrochloric  acid  and  potassium 
chlorate  given  in  another  place  (p.  283).  This  being  done, 
the  mixed  precipitate  obtained  by  passing  hydrogen  sulphid 
through  the  acidified  fluid  is  washed,  treated  with  strong  nitric 
acid,  and  evaporated  to  dryness.  A  small  quantity  of  a  strong 
solution  of  potassium  hydroxid  is  added  to  the  residue,  it  is  fil- 
tered, evaporated  to  dryness,  and  fused.  The  potassium  anti- 
monate  in  this  fluid  is  boiled  with  solution  of  tartaric  acid,  acidu- 
lated with  hydrochloric  acid,  filtered,  and  saturated  with  hydrogen 
sulphid  gas.  The  orange-red  antimonic  sulphid,  Sb2S5,  thus  ob- 
tained is  washed  on  a  Gooch  filter,1 
dried  in  a  water  oven,  and  the  free  sul- 
phur and  residual  moisture  which  are 
always  present  expelled  by  heating  in  an 
atmosphere  of  dry  carbon  dioxid.  Of 
this  residue,  which  has  been  converted 
to  black  sulphid,  Sb2S3,  100  parts  rep- 
resent 71.77  of  antimony. 

When  the  presence  of  other  poison- 
ous metals  is  suspected  the  precipitate 
made  with  hydrogen  sulphid  is  treated 
thoroughly     with     yellow     ammonium        Fro.  68.— Gooch  filter  or  funnd. 
sulphid  and  the  solution  filtered.     The 

arsenic  or  antimony  is  present  in  this  filtrate,  while  mercury, 
lead,  and  copper  remain  upon  the  filter  to  be  examined  by 

1 A  Gooch  filter  is  one  in  which  filtration  is  effected  through  an  inner  lining  of 
asbestos  felt,  which  has  been  introduced  into  the  perforated  bottom  of  a  platinum 
or  porcelain  crucible.  The  precipitate,  filtered  and  washed  in  the  usual  way,  may 
be  dried  and  ignited  without  being  removed  from  the  crucible. 


298  THE    METALS 

appropriate  methods.  The  filtrate  is  evaporated,  and  the  resi- 
due treated  with  nitric  acid  and  potassium  hydroxid  to  convert 
the  metals  into  potassium  arsenate  and  antimonate.  If  the 
presence  of  both  metals  be  suspected,  this  mixture  is  put  into 
the  sulphuric  acid  and  zinc  Marsh  apparatus,  and  the  gas  passed 
through  silver  nitrate  as  long  as  a  black  precipitate  falls.  The 
arsenic  will  be  in  the  solution,  and  is  separated  by  nitration.  The 
black  antimonid  of  silver  is  collected  on  a  filter,  washed,  boiled 
with  tartaric  acid,  acidulated  with  hydrochloric  acid,  filtered,  and 
the  filtrate  precipitated  with  hydrogen  sulphid.  Of  the  dried 
precipitate  of  orange  sulphid,  100  parts  represent  196.47  parts  of 
pure  crystallized  tartar  emetic. 


TIN  (Stannum) 

Symbol,  Sn.     Atomic  weight,  118.8. 

The  commercial  metal  is  obtained  from  tin  stone,  SnO2,  by 
reduction  with  coal.  It  is  a  silver-white  metal,  melting  at  228°  C. 
(440°  F.),  and  does  not  tarnish  in  the  air.  It  is  used  as  pure 
block  tin;  in  tin-plate,  sheets  of  iron  coated  with  thin  layers  of  tin; 
tin/oil,  thin  leaves  sometimes  containing  lead;  tin  amalgam,  silver 
coating  for  mirrors.  It  resists  the  action  of  air  and  water  so  well 
that  vessels  coated  with  it  are  universally  used  in  the  household. 
It  is  present  in  many  forms  of  bronze  as  alloys  with  copper,  in 
Britannia  metal,  alloyed  with  antimony,  and  in  soft  solder,  alloyed 
with  lead. 

Tin  forms  two  series  of  compounds  which  are  examples  of  its 
divalence  and  tetravalence.  The  first  series  are  compounds  of 
distannion,  Sn",  which  is  colorless  and  poisonous.  They  are 
called  stannous,  as  that  formed  by  the  action  of  hydrochloric  acid 
on  tin,  stannous  chlorid,  SnCl2.  This  is  a  strong  deoxidizing 
agent,  tending  to  pass  over  into  the  stannic  condition,  taking  two 
more  electric  charges,  and  reducing  arsenic,  mercury,  and  gold 
salts  to  the  metallic  state.  Dyers  use  it  in  calico  printing.  To 
check  the  tendency  to  become  turbid,  its  solutions  are  kept  stan- 
nous by  a  piece  of  metallic  tin  kept  in  the  bottle.  It  makes  a 
clear  solution  with  one-third  volume  of  water,  but  turns  to  white 
hydroxid,  Sn(OH)2,  with  more  water  unless  HC1  is  added.  On 
standing  it  absorbs  oxygen  and  deposits  the  white  oxychlorid. 
Stannic  chlorid,  SnCl4,  contains  tetrastannion,  Sn"",  which  is  the 
more  stable  ion.  It  is  a  fuming  yellow  liquid  which  tends  to 
gelatinize  by  forming  the  hydroxid,  Sn(OH)4.  It  is  formed  by 
the  action  of  nitromuriatic  acid  on  tin,  or  of  free  chlorin  on  stan- 
nous chlorid.  With  a  molecule  of  free  chlorin  the  cation  takes 


TIN  299 

up    more    positive    electricity,    the    atoms    of    chlorin    becoming 
ionized. 

Sn",  Cl',  Cl'   +    C12   =   Sn— ,  Cl',  Cl',  Cl',  Cl'. 

Toxicology. — Though  poisoning  from  tin  salts  is  rarely  re- 
ported, there  is  sufficient  evidence  to  prove  that  it  does  occur. 

Putty  powder,  a  higher  oxid  of  tin,  was  the  cause  of  death  in 
the  case  of  a  chemist  who,  by  mistake,  used  it  for  months  in  his 
pepper-box.  The  solder  used  for  fruit-cans  contains  tin  with  lead. 
This,  as  well  as  the  tin  surface,  may  be  dissolved  by  the  action  of 
acid  juices  of  fruits  or  the  fatty  acids  of  meat  and  cause  toxic 
symptoms.  In  the  case  of  canned  meats  the  danger  from  this 
source  is  slight,  as  the  compound  usually  formed  is  insoluble  in 
the  digestive  juices.  The  traces  found  in  canned  meat  and  fish 
exist  as  oxid,  though  in  rare  cases  it  is  a  basic  stannous  chlorid 
and  sometimes  a  sulphid.  The  corrosion  of  the  tin  may  increase 
slightly  after  the  second  year,  but  the  amount  is  never  anything 
but  slight,  even  after  four  years. 

Symptoms. — Tin  salts  act  as  gastro-intestinal  irritants,  causing 
sometimes  a  metallic  taste,  usually  nausea,  vomiting,  abdom- 
inal pain,  diarrhea,  cyanosis,  and  collapse.  Severe  symptoms  like 
these  were  seen  in  4  cases,  due  to  eating  tinned  cherries,  the 
strongly  acid  juice  in  the  can  showing  3.2  gr.  of  malate  of  tin 
to  the  fluidounce. 

In  an  investigation  upon  the  lower  animals  it  was  shown  that 
even  the  non-irritating  salts  given  subcutaneously,  caused  toxic 
symptoms  like  those  of  other  metals  which  undermine  the  health, 
sometimes  even  causing  death.  Tin  was  found  in  the  tissues  and 
the  urine.  Motor  and  sensory  disturbances  were  noted  in  the 
lower  extremities  of  a  young  woman  whose  skin  was  at  the  same 
period  stained  yellow  from  wearing  yello.w  silk  stockings.  More 
marked  nervous  symptoms,  like  ataxia,  were  noted  a  few  weeks 
later,  simultaneously  with  wearing  the  stockings.  The  urine  was 
albuminous,  and  gave  the  tin  reaction  for  two  months  after  the 
stockings  had  been  laid  aside.  The  stockings  were  heavily  im- 
pregnated with  tin  chlorid  to  give  them  ".body,"  and  the  absorbed 
tin  had  produced  marked  anemia.  With  the  exception  of  hysteric 
symptoms,  the  patient  recovered  in  a  few  months. 

Treatment. — Emetics  and  the  stomach-pump  should  be  used 
first,  followed  by  eggs,  bland  demulcent  drinks,  stimulants,  and 
anodynes. 

Tests. — Hydrogen  sulphid  yields  with  stannous  solutions 
brown  stannous  sulphid,  SnS,  with  stannic  solutions,  yellow  stannic 
sulphid,  SnS2  (Plate  2,  No.  6).  Both  precipitates  are  soluble  in 
ammonium  sulphid. 


300  THE    METALS 

Mercuric  chlorid  is  reduced  by  stannous  chlorid  to  a  gray 
deposit  of  metallic  mercury.  The  reduction  takes  place  in  two 
stages.  At  first  a  white  precipitate  falls  of  mercurous  chlorid 
and  later  this  is  reduced  to  the  metallic  state. 

HgCl2         +         SnCl2  Hg         +         SnCl4. 

Solutions  of  fixed  alkalis  give  with  stannous  salts  a  white 
precipitate  of  hydroxid,  Sn(OH)2,  which  is  dissolved  by  excess,  and 
on  boiling  is  reprecipitated  as  black  oxid.  With  stannic  salts  the 
white  precipitate  is  stannic  acid,  H2SnO3,  and  when  dissolved  is 
not  reprecipitated  by  boiling. 

Detection. — To  extract  the  metal  from  the  tissues  and  organic 
fluids  they  should  be  boiled  for  some  time  in  water  acidulated  with 
hydrochloric  acid,  filtered,  and  the  above  tests  applied  to  the  filtrate. 


V.— THE  COPPER  GROUP 

COPPER,  mercury,  lead,  bismuth,  silver,  and  cadmium  belong 
to  a  group  of  heavy  metals  whose  sulphids  are  insoluble  in  water, 
dilute  acids,  or  ammonium  sulphid. 

COPPER   (Cuprum) 

Symbol,  Cu.     Atomic  weight,  63.6. 

Occurrence. — Copper  is  found  in  the  free  condition;  as  cuprite 
or  oxid;  azurite  and  malachite,  the  blue  and  green  carbonates; 
and  as  copper  pyrites,  CuFeS2.  By  processes  of  roasting  and 
reduction  the  metal  is  obtained  from  these  ores  and  finally  puri- 
fied by  electrolysis  in  a  bath  of  its  sulphate,  using  impure  copper 
as  an  anode. 

Wide  Distribution  in  Nature.— Not  only  is  copper  to  be  found 
in  native  masses  and  in  its  ores,  but  in  minute  proportions  it  is  a 
constituent  of  many  common  minerals  and  soils.  Natural  water 
takes  up  a  trace,  and  vegetation  thus  derives  it  from  soil  and  from 
water.  Careful  analysis  has  detected  it  in  edible  roots,  such  as 
the  turnip,  in  fruits,  berries,  salads,  wheat,  barley,  and  other  cereals, 
coffee,  chocolate,  and  quinin.  From  plants  as  food  it  is  found  to 
be  derived  by  animals — domestic  and  wild.  Even  oysters  some- 
times show  a  trace.  Constantly  present  in  our  chief  foods,  it  is  not 
surprising  that  it  is  found  in  the  body  of  man.  Leaving  out 
of  the  count  foods  possibly  contaminated  artificially,  it  is  esti- 
mated that  each  of  us  takes  daily  about  i  mg.  (0.015  gr.)  of  cop- 


COPPER  301 

per.  At  the  same  time  it  is  not  a  physiologic  constituent  of  the 
body,  like  iron. 

Physical  Properties.— Copper  is  a  heavy,  bright-red  solid 
which  in  moist  air  becomes  coated  with  a  green  carbonate.  It 
soon  loses  its  red  luster,  taking  a  brown  coat  of  oxid  or  sulphid. 
When  heated  it  oxidizes  in  air  to  form  a  black  oxid.  Copper  is 
of  value  in  the  arts  because  it  is  strong,  malleable,  ductile,  a  good 
conductor  of  electricity,  and  a  resistant  to  most  reagents,  under 
ordinary  conditions. 

Brass  is  an  alloy  of  about  2  parts  copper  to  i  of  zinc. 

Bronzes  contain  copper,  tin,  and  sometimes  zinc. 

Bell  metal  is  an  alloy  of  copper  and  tin. 

Phosphorus  bronze  is  a  copper  bronze  containing  phosphorus. 

Aluminium  bronze,  which  is  yellow  and  resembles  gold  in 
appearance,  is  an  alloy  of  copper  and  8  per  cent,  aluminium. 

German  silver  is  an  alloy  of  copper,  nickel,  and  zinc. 

Coin  silver  contains  10  per  cent,  of  copper. 

Copper  dissolves  in  nitric  acid,  in  hot  sulphuric  acid,  and,  when 
exposed  to  the  air,  in  hydrochloric  acid  and  in  ammonia.  Even 
distilled  water  will  in  time  take  up  some.  One  hundred  cubic 
centimeters  may  dissolve  0.3  mg.  of  copper  or  0.2  gr.  in  i  gal. 
Water  kept  a  few  hours  in  a  brightly  polished  copper  vessel  takes 
up  the  metal  as  colloidal  solution  in  amounts  harmless  to  man,  but 
distinctly  bactericidal.  Natural  waters  containing  salts,  especially 
the  chlorids,  exert  still  more  solvent  powers.  The  syrups  and  fats 
dissolve  it,  and  the  fatty  acids  readily  combine  with  it.  Vinegar, 
acid  wines,  and  subacid  fruits  kept  for  a  few  hours  in  copper 
vessels  are  found  to  contain  the  metal. 

The  Ions  of  Copper. — Two  series  of  copper  salts  are  known, 
called  respectively  cuprous  and  cupric.  In  the  cuprous  salts  the 
ion  is  univalent,  monocuprion,  Cu*;  in  the  cupric  it  is  bivalent, 
dicuprion,  Cu".  The  latter  condition  is  the  more  stable,  and  is 
characterized  by  the  blue  color  of  its  salts.  It  is  not  poisonous, 
but  some  of  its  salts  are  irritants  in  large  doses. 

When  a  piece  of  zinc  is  immersed  in  a  copper  sulphate  solution 
the  copper  ion  Cu"  yields  its  two  charges  to  an  atom  of  zinc  and 
is  deposited  as  an  atom;  the  zinc  taking  the  charges  passes  from 
the  atomic  to  the  ion  state  as  zinc  sulphate  in  solution. 

Cu-,  (SO4)"     +      Zn     =     Zn",  (SO4)"     +      Cu. 

This  is  the  second  mode  of  ion  formation,  which  consists  in  a 
simple  transference  of  electricity  from  metal  to  metal. 

Electrolytic  Solution  Tension. — A  metal  immersed  in  an  aqueous 
solution  exerts  a  pressure  which  tends  to  send  off  ions  from  the 


302 


THE    METALS 


metal  into  the  solution.  This  solution  tension  is  high  with  zinc, 
which  has  a  great  tendency  to  ionize,  but  lower  with  copper,  which, 
therefore,  gives  place  to  the  zinc.  It  is  a  general  principle  that 
metals  with  great  solution-tension  precipitate  from  their  salts  those 
that  have  less  (p.  90). 

Oxids. — The  two  ions  are  represented  in  the  oxids:  cuprous, 
Cu2O,  and  cupric,  CuO. 

Cuprous  oxid  is  the  red  powder  precipitated  in  Trommer's  test 
for  glucose.  A  hot  alkaline  solution  of  a  cupric  salt  is  reduced 
red  by  the  sugar  in  simple  solutions,  but  in  urine  the  precipitate 
is  yellow  or  yellowish  red  (Plate  8,  Fig.  3). 

Cupric  oxid  is  the  black  coating  formed  on  metallic  copper  when 
heated  to  dull  redness  in  oxygen  or  air.  If  the  oxid  be  heated 
to  a  higher  degree  in  the  presence  of  hydrogen  it  gives  up  the 
oxygen  to  form  water. 

Cupric  Hydroxid  (Cu(HO)2). — When  a  copper  salt  is  acted 
upon  by  an  alkaline  hydroxid,  a  light  blue  precipitate  is  formed. 
It  remains  insoluble  in  potassium  and  sodium  hydroxids,  but  in  an 
excess  of  ammonium  hydroxid  it  passes  into  solution  with  a  deep 
sapphire-blue  color.  A  new  ion,  cuprammonium,  Cu(NH3)4**, 
has  been  produced,  in  which  ammonia  as  a  constituent  persists 
even  when  the  salt  has  been  separated  as  a  dark  blue  solid.  In 
performing  Trommer's  test  without  glucose,  the  addition  of  potas- 
sium hydroxid  precipitates  the  blue  hydroxid: 

CuS04     +     2KHO  Cu(HO)2     +     K2SO4. 

When  heated,  the  turbid  blue  fluid  turns  black,  as  the  hydroxid 
changes  to  cupric  oxid: 

Cu(HO)2  H20  +  CuO. 

But  if  glucose  be  present,  oxygen  is  taken  out  and  red  cuprous 
oxid  formed  (Plate  8,  Fig.  3),  in  accordance  with  this  equation: 

2Cu(HO)2  2H2O          +          O          +          Cu2O. 

Cuprous  chlorid,  CuCl,  is  formed  when  hydrochloric  acid  is 
treated  with  excess  of  copper  and  the  result  added  to  water.  It 
absorbs  oxygen,  changing  to  cupric  chlorid  and  also  carbon  mon- 
oxid,  forming  Cu2Cl2CO  .  2H2O. 

Cupric  chlorid,  CuCl2,  is  formed  when  cupric  hydroxid  is  dis- 
solved in  hydrochloric  acid:  Cu(HO)2  + 2HC1=  CuCl2  + 2H2O. 

In  concentrated  solutions  it  is  only  slightly  dissociated  and, 
therefore,  has  the  greenish-yellow  color  of  the  CuCl2  molecule; 


COPPER  303 

but  when  the  solution  is  diluted,  and  thereby  the  dissociation 
increased,  the  blue  color  of  the  Cu**  ions  appears.  By  heating  this 
blue  solution  or  by  adding  excess  of  chlorin  the  dissociation  is 
driven  back  and  the  blue  turns  green  and  finally  yellow. 

Copper  sulphate,  CuSO45H2O,  commonly  known  under  the 
trivial  name  of  bluestone,  occurs  in  large,  blue,  slightly  efflorescent 
crystals,  freely  soluble  in  water,  and  having  a  strong  metallic  taste. 
The  blue  color  is  explained  by  the  dissociation  of  the  blue  cupric 
ion  in  the  water  of  crystallization.  When  heated  the  water  is 
driven  off  and  the  anhydrous  salt  is  white.  It  is  used  in  medicine 
as  an  external  application  for  its  astringent  or  mild  stimulating 
qualities.  Internally,  in  doses  of  J  to  2  gr.,  it  is  given  as  a  tonic 
and  astringent;  in  doses  of  5  to  10  gr.  it  acts  as  a  prompt  emetic. 
It  is  employed  in  phosphorus-poisoning  as  an  antidote  and  also 
as  an  emetic.  In  very  large  doses  it  is  poisonous,  and  has  been 
used  both  for  suicidal  and  for  homicidal  purposes. 

Copper  subacetate,  Cu2C2H3O2,  CuO,  is  prepared  by  treating 
metallic  copper  with  acetic  acid  in  the  air.  It  crystallizes  in  blue- 
green  prisms.  In  an  impure  form  it  is  known  as  verdigris.  The 
same  name  is  popularly  given  to  other  green  salts  of  copper,  as 
the  oleate  and  carbonate.  Verdigris  in  medicine  is  used  only 
externally.  In  the  arts  it  is  frequently  employed. 

Toxicology. — The  irritant  salts  are  copper  sulphate  (blue 
vitriol),  copper  subacetate  (verdigris),  and  copper  aceto-arsenite 
(Paris  green).  As  the  poisonous  properties  of  the  last  named 
are  dependent  chiefly  upon  the  arsenic,  it  has  been  considered 
among  the  compounds  of  that  metal  (p.  290). 

Metallic  copper  is  not  poisonous,  as  is  demonstrated  by  the  use 
of  copper  wire  for  surgical  sutures  and  the  absence  of  injurious 
consequences  when  a  copper  coin  is  swallowed.  When  used  for 
sutures  copper  wire  is  found  to  exert  a  powerful  inhibitory  action 
on  bacteria;  in  fact,  much  greater  than  that  of  any  other  metal. 

Symptoms  of  Acute  Poisoning. — Out  of  8  cases  registered  in 
England  in  ten  years,  3  were  suicidal,  5  were  accidental,  and  none 
was  homicidal.  The  very  disagreeable  taste  of  copper  salts  pre- 
vents the  criminal  use.  The  onset  of  the  symptoms  may  be  said 
to  begin  with  this  coppery  astringent  taste  and  the  feeling  of  tight- 
ness in  the  throat.  In  a  few  minutes  nausea  and  violent  vomiting 
of  greenish  matters  begin.  Soon  appear  thirst,  pain  in  the  stomach, 
and  colic,  with  violent  purging  of  stools  having  the  same  green 
hue  of  the  vomit.  Ammonia-water  added  to  the  green  excreta 
will  turn  them  blue,  and  thus  distinguish  this  copper-green  from 
bile.  The  urine  is  scanty  and  may  become  albuminous,  inky  from 
changed  hemoglobin,  and  loaded  with  tube-casts.  The  later 
stages  are  characterized  by  nervous  phenomena,  such  as  pains, 


304  THE    METALS 

spasms  which  may  be  tetanic,  paralysis,  delirium,  and  collapse. 
In  the  course  of  a  few  days  jaundice  appears  as  a  result  of  involve- 
ment of  the  liver. 

Fatal  Dose. — Owing  to  the  energetic  emetic  properties  of  large 
doses  of  copper  sulphate,  evacuation  of  the  stomach  is  so  prompt 
that  we  have  no  means  of  determining  how  much  would  prove 
fatal.  On  the  one  hand,  a  child  four  and  a  half  years  old  has 
recovered  after  a  dose  of  over  J  oz.  of  copper  sulphate;  on  the  other 
hand,  an  adult  has  succumbed  to  a  dose  of  i  oz.  of  verdigris. 

Fatal  Period. — As  a  rule,  life  is  prolonged  for  several  days,  the 
patient  sometimes  almost  recovering  from  the  symptoms  of  gastro- 
enteric  irritation  and  finally  dying  from  the  effects  of  the  absorbed 
poison.  Copper  sulphate  has  caused  death  in  four  hours. 

Treatment. — Evacuation  of  the  stomach  must  first  be  obtained 
by  stimulating  the  natural  effort  at  vomiting.  The  antidote  is  the 
albumin  of  egg  or  the  casein  of  milk.  Eggs  beaten  in  warm  water 
should  be  given  freely.  If  vomiting  does  not  occur  or  is  not 
active,  the  stomach-pump  should  be  resorted  to  and  the  stomach 
washed  out  with  milk  or  eggs  and  water.  A  milk  diet  with  castor 
oil  will  favor  removal  from  the  intestine. 

Postmortem  Appearances. — Congestion,  swelling,  softening, 
and  excoriations  of  the  mucous  membrane  of  the  stomach  and 
bowels  are  usually  found.  The  colon  sometimes  shows  large 
ulcerations.  A  bluish  discoloration  of  the  lining  membrane 
indicates  that  all  the  copper  has  not  been  evacuated.  The  liver 
may  be  soft  and  fatty,  the  kidneys  swollen,  and  the  tubules  closed 
with  bloody  casts. 

Chronic  Poisoning. — Until  comparatively  recent  times  it  was 
thought  that  the  slow  introduction  of  minute  doses  of  copper 
was  injurious  to  the  tissues  by  causing  such  pathologic  changes 
as  are  known  to  be  due  to  certain  other  poisons,  such  as  phos- 
phorus, arsenic,  antimony,  lead,  and  mercury.  It  has  been  proved 
that  as  a  slow  poison  copper  belongs  to  a  different  category — 
that  of  silver  and  zinc.  To  produce  toxic  phenomena  it  must  be 
given  freely  and  intentionally.  After  a  long  course  there  are 
functional  disturbances  of  the  muscular  and  nervous  systems, 
anemia,  and  cachexia.  As  soon  as  the  administration  ceases  the 
functions  are  restored  and  the  subject  spontaneously  recovers 
from  the  cachexia.  It  has  not  been  demonstrated  that  any  doses, 
however  large,  which  have  been  taken  with  food  have  ever  caused 
death,  while  medium  doses  in  the  beginning  act  as  simple  emetics, 
tolerance  is  rapidly  established,  and  administration  can  be  con- 
tinued for  six  months  with  little  impairment  of  health. 

Copper  salts  are  extensively  used  to  impart  a  lively  green 
color  to  pickled  cucumbers  and  canned  peas  and  beans.  An 


COPPER  305 

insoluble  green  compound  is  formed  between  copper  and  acid 
phyllocyanic  from  the  chlorophyl  in  the  vegetable.  Elaborate 
researches  have  been  carried  out  in  various  countries  under  the 
highest  sanitary  authorities  to  settle  the  limit  of  copper  admissible 
as  not  injurious  to  health.  The  U.  S.  Board  of  Food  Inspection 
maintains  (1911)  that  copper  sulphate  used  for  the  greening  of 
vegetables  is  injurious  and  should  be  prohibited,  but  for  the  present 
admits  to  entry  into  the  United  States  those  vegetables  which  do 
not  contain  an  excessive  amount.  The  label  must  bear  the  state- 
ment that  copper  sulphate  or  other  copper  salts  have  been  used  to 
color  the  vegetables.  Less  than  2  gr.  per  Ib.  is  sufficient  for  this. 

At  one  time  it  was  generally  believed  that  workers  in  copper  or 
its  compounds,  such  as  malachite,  were  liable  to  a  disease  called 
" copper  colic,"  which  differed  from  lead  colic  in  that  diarrhea 
was  present  instead  of  constipation;  there  was  greater  prostration, 
its  duration  was  shorter,  and  the  prognosis  was  good.  It  is  now 
maintained  by  able  investigators  that  such  symptoms  are  not  due 
to  copper,  but  to  the  lead  and  arsenic  which  are  impurities  in  most 
ores  and  in  the  commercial  metal,  or  to  the  lead  in  the  solder  used 
by  the  operator.  This  is  borne  out  by  the  fact  that  after  more 
than  one  attack  " wrist-drop"  or  lead-palsy  is  apt  to  supervene. 
No  symptoms  of  poisoning  are  found  in  certain  copper  workers 
who  show  copper  as  a  purplish  or  bluish  line  on  the  gums,  whose 
hair  turns  green,  and  whose  urine  stains  the  ground  green.  "The 
contention  that  there  is  no  chronic  copper  poisoning  in  men  or  animals 
(comparable  to  lead  or  mercury)  is  at  present  uncontradicted." 

Tests. — Hydrogen  Sulphid  Test. — A  stream  of  hydrogen  sul- 
phid  passed  through  an  acid  solution  of  a  copper  salt  yields  a 
brownish  precipitate  of  copper  sulphid,  freely  soluble  in  warm 
nitric  acid,  slightly  so  in  excess  of  ammonium  sulphid,  but  insoluble 
in  the  caustic  alkalis. 

Ammonia  Test. — A  solution  of  a  copper  salt  is  either  green  or 
blue.  By  adding  ammonium  hydroxid  in  excess  to  a  slightly 
colored  solution,  cupric  hydroxid  is  formed  and  dissolved  to 
make  a  much  deeper  sapphire-blue  solution. 

Fallacies.— The  salts  of  nickel  give  the  same  deep  blue  solu- 
tion. 

Delicacy. — The  change  in  color  is  recognizable  in  i  gr.  of  a 
solution  containing  -g^Vo"  gr.  of  copper  oxid. 

Potassium  Ferrocyanid  Test.— This  reagent  precipitates  from 
a  strong  copper  solution  the  reddish-brown  copper  ferrocyanid. 
When  the  solution  is  very  dilute  no  precipitate  falls,  but  the 
solution  turns  reddish  brown.  The  brown  precipitate  is  insoluble 
in  acetic  and  hydrochloric  acids,  but  with  ammonium  hydroxid 
forms  a  greenish-blue  liquid. 


306  THE    METALS 

Fallacies. — Solutions  of  uranium  salts  yield  a  similar  brown 
precipitate,  but  when  this  is  treated  with  excess  of  ammonium 
hydroxid  the  liquid  is  yellow,  not  blue. 

Interferences. — A  trace  of  iron  will  give  a  blue  color  with  this 
reagent  and  thus  mask  the  result. 

Delicacy. — A  distinct  red  reaction  can  be  obtained  from  25999 
gr.  of  copper  oxid. 

Iron  Test. — This  test  separates  copper  in  the  metallic  state.  It 
is  performed  by  immersing  a  steel  needle  or  other  piece  of  bright 
steel  or  iron  in  the  suspected  liquid  slightly  acidulated.  If  copper 
be  in  solution,  it  will  be  deposited  as  a  reddish  layer  on  the  iron. 
The  solution  tension  of  iron  is  much  higher  than  that  of  copper; 
hence,  the  ions  of  copper  give  place  to  the  iron  and  are  ^precip- 
itated  as  metallic  molecules.  To  prove1  that  this  film  is 'copper 
it  is  dipped  in  ammonium  hydroxid  and  exposed  to  the  air,  when 
the  film  of  copper  turns  blue. 

Galvanic  Zinc  Test. — Very  delicate  results  can  be  obtained  by 
immersing  in  a  copper  solution  a  galvanic  couple  made  by  wrap- 
ping platinum  wire  around  a  piece  of  zinc-foil.  The  platinum  is 
soon  discolored  by  a  deposit,  the  nature  of  which  can  be  estab- 
lished by  exposing  it  to  the  vapors  arising  from  potassium  bromid 
when  treated  with  sulphuric  acid.  The  deposit  changes  in  color, 
and  if  rubbed  on  white  porcelain  leaves  a  violet  mark. 

Electrolytic  Test. — Having  obtained  the  copper  in  solution  and 
concentrated  it,  make  it  acid  with  hydrochloric  acid  and  put  it  in 
a  weighed  dish  of  platinum  which  is  connected  with  the  zinc  pole 
or  cathode  of  a  battery.  A  strip  of  platinum-foil  as  anode  is 
immersed  in  the  tested  solution  for  twenty-four  hours.  In  that 
time  all  the  copper  will  be  deposited  on  the  platinum  dish.  To 
make  a  quantitative  estimate  the  dish  must  be  washed,  dried,  and 
weighed  again.  The  gain  represents  the  total  amount  of  copper 
in  the  volume  of  tested  solution. 

Separation  of  Copper  from  Animal  Matters. — The  organic 
matter  in  the  contents  of  the  stomach,  or  in  the  liver,  brain, 
or  other  tissues,  must  be  destroyed  by  burning  to  an  ash  and 
extracting  with  nitric  acid,  or  boiling  with  hydrochloric  acid 
and  potassium  chlorate,  according  to  the  systematic  procedure 
given  on  p.  283.  By  evaporation  the  excess  of  acid  can  be  re- 
moved, and  the  residue,  dissolved  in  acidulated  water,  may  be 
tested  by  the  methods  given  above. 

MERCURY   (Hydrargyrum) 

Symbol,  Hg.     Atomic  weight,  200. 

Occurrence. — Quicksilver  is  found  native,  but  the  chief  source 
is  the  sulphid  ore,  cinnabar,  HgS.  By  simple  heat  the  sulphur 


MERCURY  307 

oxidizes  to  SO2  and  the  volatile  metal  vaporizes,  to  be  collected 
as  a  distillate. 

Amalgams. — Mercury  is  a  solvent  for  gold,  silver,  zinc,  metals 
of  the  alkalis,  and  the  alkaline  earths  and  mariy  other  metals. 
This  mercurial  solution  is  called  an  amalgam  of  the  metal  dissolved. 

Physical  Properties.— Mercury  is  the  only  metal  that  is  in  the 
liquid  state  at  ordinary  temperatures.  It  freezes  at  —39.4°  C. 
(-40°  F.),  and  boils  at  357°  C.  (675°  F.),  but  at  all  ordinary 
temperatures  it  vaporizes  spontaneously.  Having  this  great 
range  of  fluidity  joined  to  the  high  density  of  13.595,  and  not 
wetting  glass,  it  is  invaluable  in  the  construction  of  barometers, 
thermometers,  manometers,  and  other  scientific  instruments. 

Chemical  Properties, — Mercury  retains  its  silver-white, 
metallic  luster  in  the  air,  because  it  combines  with  oxygen  only 
at  high  temperatures.  It  unites  directly  with  chlorin  and  the 
other  halogens  at  ordinary  temperatures. 

The  Ions  of  Mercury. — Mercury  forms  two  series  of  salts, 
mercurous  and  mercuric,  in  which  the  anions  of  acids  are  com- 
bined with  two  different  elementary  ions  of  mercury.  In  one 
series  the  mercurous  ion  (monomercuriori),  Hg",  is  univalent; 
in  the  other  the  mercuric  ion  (dimercuriori) ,  Hg",  is  bivalent. 
With  an  excess  of  metallic  mercury  the  product  of  the  action  of  an 
acid  such  as  nitric  is  mercurous.  Without  that  excess  the  mer- 
curous nitrate  passes  to  the  condition  of  mercuric.  Both  ions  are 
poisonous  to  bacteria  and  animal  life.  In  the  body  the  mercurous 
ion  forms  with  chloridion  a  mercurous  salt  of  low  solubility  and, 
therefore,  of  feeble  powers,  but  the  mercuric  ion  forms  salts  of 
higher  solubility  and  of  greater  toxic  activity. 

The  metal  is  cleansed  from  impurities  that  impair  its  luster  and 
make  it  "drag  a  tail"  by  shaking  with  dilute  sulphuric  acid  to 
which  a  few  drops  of  solution  of  potassium  bichromate  are  added 
from  time  to  time.  The  contaminating  metals  are  oxidized  and 
dissolved  and  can  be  washed  away. 

When  metallic  mercury  is  finely  triturated  the  globules  re- 
main separate  if  the  trituration  has  been  done  in  the  presence  of 
some  substance  which  gives  a  coating,  such  as  fatty  matter  or  a 
confection. 

The  metal  has  been  given  in  the  pure  state  to  remove  obstruc- 
tion from  the  bowels  mechanically,  with  no  injurious  consequences 
unless  retained  for  a  number  of  days.  The  metal  is  present, 
finely  divided,  and  possibly  oxidized  in  "gray  powder"  (hydrar- 
gyrum cum  creta],  "blue  mass"  (massa  hydrargyri),  "blue  oint- 
ment" (unguentum  hydrargyri}.  In  this  condition,  and  also  if 
inhaled  in  the  state  of  vapor,  the  metal  is  converted  by  the  fluids 
of  the  body  into  active  compounds  which  exhibit  all  its  poisonous 


308  THE    METALS 

effects.  Among  its  poisonous  salts  are  its  oxids,  iodids,  mercur- 
ammonium  chlorid,  mercuric  nitrate,  and  mercuric  chlorid  (cor- 
rosive sublimate). 

MercUfOUS  Oxid  (Hg2O)  (Black  Oxid).— This  black  insol- 
uble powder  is  precipitated  from  solutions  of  mercurous  salts  by 
bases: 

2HgCl     +     2NaOH     =     2NaCl     +     Hg2O     +     H2O. 

It  is  unstable,  changing  in  time  to  mercuric  oxid  and  metallic 
mercury.  Sunlight  hastens  this  conversion: 

Hg20  HgO         +         Hg. 

Lotio  hydrargyri  nigra,  or  " black  wash,"  is  a  mixture  in  which 
calomel  is  converted  to  mercurous  oxid  by  lime-water,  leaving 
calcium  chlorid  in  solution: 

2HgCl      +      Ca(OH)2      =      CaCl2      +      Hg2O      +      H2O. 

Mercuric  oxid,  HgO,  is  obtained  as  a  yellow  powder  by 
precipitation  from  mercuric  salts  with  soluble  bases. 

Hydrargyri  oxidum  flavum  (yellow  precipitate)  is  formed  when 
a  solution  of  mercuric  chlorid  is  poured  into  a  solution  of  sodium 
hydroxid: 

HgCl2      +      2NaHO      =      2NaCl      +      HgO      +      H2O. 

It  is  slightly  soluble  in  water,  imparting  an  alkaline  reaction 
and  metallic  taste. 

The  color  of  mercuric  oxid  depends  upon  the  fineness  of  division. 
When  precipitated  from  cold  solutions  it  is  yellow;  from  hot 
solutions  it  is  orange.  In  both  cases  it  is  finely  divided  and  in 
consequence  energetic. 

As  the  "red  precipitate"  it  is  more  compact,  coarser,  and 
crystalline;  its  official  name  then  being  hydrargyri  oxidum  rubrum. 
It  is  obtained  by  heating  either  mercurous  or  mercuric  nitrate 
moderately,  oxygen  and  nitrogen  peroxid  being  driven  off  and 
the  red  oxid  left  behind: 

Hg(N03)2     =     HgO     +     2N02     +     O. 

Mercuric  oxid  is  partly  dissolved  and  partly  suspended  in 
"  yellow  wash,"  lotio  hydrargyri  flava,  which  is  obtained  when  a 
solution  of  corrosive  sublimate  is  poured  into  lime-water: 

HgCl2      +      Ca(OH)2      =      CaCl2      +      HgO      +      H2O. 


MERCURY  309 

Oleatum  hydrargyri  contains  25  per  cent,  by  weight  of  the 
yellow  oxid. 

There  is  a  ic-per  cent,  ointment  of  "yellow  precipitate," 
unguentum  hydrargyri  oxidi  flavi,  and  one  of  "red  precipitate" 
of  the  same  strength,  unguentum  hydrargyri  oxidi  rubri. 

MercurotlS  chlorid,  HgCl  (hydrargyrum  chloridum  mite,  mild 
chlorid,  calomel),  can  be  made  by  subliming  a  mixture  of  mer- 
curic chlorid  and  metallic  mercury: 

HgCl2          +  Hg  2HgCl. 

Precipitated  calomel  is  a  more  active  form,  owing  to  the  fineness 
of  its  division.  A  solution  of  mercurous  nitrate  yields  mercurous 
chlorid  when  acted  upon  by  sodium  chlorid: 

HgNO3         +         Nad  HgCl         +         NaNO3. 

Calomel  is  a  heavy,  white,  insoluble,  tasteless  powder  that  is 
not  considered  poisonous.  If  retained  too  long  it  changes  to 
some  more  active  compound,  such  as  the  poisonous  mercuric 
chlorid,  and  then  produces  systemic  symptoms.  It  is  so  exten- 
sively used  that  milder  toxic  effects  are  not  infrequent,  owing  to 
these  changes  in  the  stomach  or  in  the  prescription,  due  to  incom- 
patible association.  It  is  probable  that  most  of  the  few  fatal  cases 
reported  were  brought  about  by  the  conversion  of  the  calomel 
by  the  fluids  of  the  body  into  some  poisonous  salt.  It  is  readily 
oxidized  to  the  mercuric  chlorid.  It  is  converted  into  mercuric 
chlorid  by  nitrohydrochloric  acid  and  chlorin-water,  and  probably 
to  a  slight  extent  also  by  hydrochloric  acid  and  alkaline  chlorids. 
It  is  changed  to  oxid  or  reduced  by  the  alkaline  bases  and  carbo- 
nates. Prolonged  exposure  to  sunlight  changes  it  to  metallic 
mercury  and  mercuric  chlorid,  as  is  shown  by  this  equation: 

2HgCl  Hg  +  HgCl2. 

The  HgCl  is  of  such  difficult  solubility  that  few  Hg  ions  are 
dissociated  from  it  i.n  a  brief  sojourn  in  the  body,  but  the  HgCl2  is 
freely  soluble,  dissociates  Hg  ions  promptly,  and,  therefore,  is 
more  active  in  every  way.  Calomel  should  be  kept  in  opaque 
containers  in  order  to  prevent  this  change. 

It  is  incompatible  with  halogens,  chlorids,  bromids,  iodids, 
sulphates,  carbonates,  hydrates,  acids,  alkalis,  soap,  cocain,  hydro- 
cyanic acid  and  cyanids,  sulphurous  acid,  hydrogen  peroxid,  iodo- 
form,  salts  of  lead,  copper,  or  silver;  sugar,  tragacanth,  acacia, 
pilocarpin,  antipyrin,  acetanilid,  and  sweet  spirits  of  niter. 


3io 


THE    METALS 


Dose  as  cathartic:  5  to  15  gr.  (0.33-1.0  gm.);  as  internal  anti- 
septic, J  to  J  gr.  every  hour. 

Mercuric  Chlorid  (HgCl2)  (Hydrargyri  Chloridum  Corro- 
sivum,  Corrosive  Chlorid,  Bichlorid  oj  Mercury}. — This  salt  is  com- 
monly called  corrosive  sublimate,  because  it  is  a  local  corrosive 
and  is  prepared  by  subliming  a  mixture  of  mercuric  sulphate  and 
sodium  chlorid: 


HgS04 


2NaCl 


Na2S04 


HgCl2. 


Corrosive  sublimate  is  usually  seen  in  crystalline  masses;  it 
sublimes  at  82.2°  C.  (180°  F.),  and  is  deposited  in  needles,  in 
octahedra,  or  in  stellate  aggregations  of  crystalline  plates  (Fig.  69). 


FIG.  69.— Sublimate  of  mercuric  chlorid,  magnified.     Stellate  crystals. 

It  has  no  odor,  but  an  acrid,  metallic  taste.  It  is  soluble  in  16 
parts  of  cold  water  and  3  parts  of  boiling  water,  but  is  far  more 
soluble  in  solutions  of  common  salt  or  other  alkaline  chlorids, 
forming  salts  of  the  anions  (HgCl3)'  and  (HgClJ",  such  as  Na(HgCl3) 
and  Na2(HgCl4),  which  have  less  bactericidal  power  than  the 
simple  mercuric  chlorid  in  a  concentration  containing  the  same 
amount  of  mercury.  Mercuric  chlorid  alone  is  dissociated  very 
little,  as  compared  with  sodium  chlorid  alone.  The  double  chlorid 
is  dissociated  even  less.  The  germicidal  power  of  mercury  salts 
is  proportionate  to  the  simple  mercuric  ion  and  not  to  the  other 


MERCURY  311 

component.  Hence,  the  addition  of  NaCl  to  a  concentrated 
solution  of  HgCl2  locking  up  some  of  the  Hg  in  the  complex 
(HgCl3)'  lessens  the  number  of  active  Hg"  ions  and  lowers  the 
germicidal  power.  To  make  antiseptic  solution  it  is  best  to  use 
pastilles  containing  not  more  than  4  parts  of  NaCl  to  i  of  HgCl2 
and  dissolving  only  i  gram  per  liter.  At  this  dilution  the  NaCl 
favors  the  solution  of  the  HgCl2  without  material  reduction  of 
germicidal  action.  In  the  presence  of  the  organic  exudations  of 
a  wound,  changes  occur  which  cause  the  dissociation  of  more 
mercuric  ions  to  take  the  place  of  those  taken  up  by  the  protein. 
Mercuric  chlorid  makes  a  definite  insoluble  compound  with  proteid 
matter,  and  is,  therefore,  fatal  to  low  forms  of  animal  and  vegetable 
life.  In  the  dry  powder  it  is  inactive  chemically  and  also  as  a 
bactericide.  Dissolved  in  alcohol  or  ether  it  has  little  antiseptic 
power  because  in  these  solvents  it  dissociates  very  few  Hg"  ions. 
In  water  it  supplies  the  poisonous  mercuric  ion  and  exhibits  its 
reactions  very  well.  A  solution  of  it  is  used  in  the  household 
to  destroy  bedbugs,  and  by  taxidermists  to  preserve  skins  and 
mounted  preparations.  In  antiseptic  surgery  it  is  extensively 
employed  in  irrigating  solutions  of  i:  4000  or  even  i :  1000  of  water. 
As  it  attacks  metals  it  is  not  suited  for  disinfecting  metallic  vessels 
or  instruments. 

It  is  incompatible  with  sulphurous  acid  and  other  reducing 
agents  (which  reduce  it  to  calomel),  ferrum  reductum,  arsenous, 
antimonious,  and  ferrous  salts;  formic  acid;  albumin,'  gelatin, 
alkalis;  alkaloids;  soap;  lime-water;  bromids;  iodids;  borax; 
carbonates,  phosphates,  hypophosphites,  salts  of  copper,  zinc, 
lead,  and  silver;  syr.  sarsaparilla  comp.;  tannic  acid  and  vegetable 
astringents.  Dose:  -§V  to  TV  gr.  (0.00075-0.006  gm.). 

Mercurous  lodid  (Hgl)  (Hydrargyri  lodidum  Flavum,  Green 
lodid,  Yellow  lodid,  Protiodid}. — An  acid  solution  of  mercurous 
nitrate  treated  with  potassium  iodid  gives  a  yellow  precipitate  of 
mercurous  iodid: 

HgN03       4-       KI       =        KN03      +       Hgl. 

It  is  a  tasteless,  almost  insoluble,  powder  which  decomposes  by 
sunlight  into  mercuric  iodid  and  mercury,  becoming  greenish  from 
the  presence  of  the  blue  particles  of  metallic  mercury.  Thus: 
2HgI  =  Hg-f  HgI2.  Mercurous  iodid  should  not  be  prescribed 
with  soluble  iodids  or  the  more  energetic  mercuric  iodid  will  be 
formed.  Dose:  J  to  i  gr.  (0.011-0.066  gm.). 

Mercuric  Iodid  (HgI2)  (Hydrargyri  lodidum  Rubrum,  Red 
lodid,  Biniodid). — When  a  solution  of  potassium  iodid  is  added  to 
one  of  mercuric  chlorid  a  yellow  precipitate  falls,  which  at  once 


312  THE    METALS 

turns  red  on  the  side  to  the  light  and  eventually  gets  red  through- 
out. This  red  iodid  dissolves  on  the  addition  of  an  excess  of 
potassium  iodid: 

HgCl2       +        2KI  2KC1        +        HgI2. 

A  brilliant-red,  tasteless  powder,  it  is  very  sparingly  soluble  in 
water.  When  it  dissolves  in  the  iodid  of  potassium,  a  salt  is 
formed,  called  potassium  mercuric  iodid,  by  this  reaction: 

2KI  +  HgI2  K2HgI4. 

This  salt  does  not  show  the  usual  chemical  reactions  of  mercury, 
and  is  less  apt  to  salivate  than  simple  HgCl2  in  doses  containing 
the  same  amount  of  Hg.  Obviously  it  dissociates  very  few  simple 
mercuric  ions  and  is  properly  regarded  as  a  salt,  the  anion  of  which 
is  (HgI4)".  Nessler's  reagent  is  prepared  by  adding  potassium 
hydroxid  to  this  potassium  mercuric  iodid.  It  is  a  sensitive  test 
for  ammonia.  Dose  of  mercuric  iodid:  •£$  to  YU  gr.  (0.0013- 
0.006  gm.). 

Its  incompatibles  are  the  same  as  those  of  mercuric  chlorid 
given  above. 

Mercuric  Sulphid  (HgS)  (Ver million).— There  is  no  mer- 
curous  sulphid,  but  the  mercuric  compound  is  very  stable.  It  is 
found  in  the  ore  cinnabar,  and  can  be  formed  by  direct  union  of 
the  elements.  The  black  precipitate  formed  on  passing  hydrogen 
sulphid  through  a  mercurous  solution  is  not  mercurous  sulphid, 
unless  as  a  transient  phase.  Its  final  composition  is  a  mixture  of 
mercuric  sulphid  and  mercury: 

2HgCl     +     H2S     =     HgS     +     Hg     +     2HC1. 

If  the  hydrogen  sulphid  be  passed  through  a  mercuric  solu- 
tion, whether  acid  or  neutral,  the  precipitate  is  at  first  white,  then 
yellow,  red,  and  black.  These  are  more  or  less  complex  and 
variable  compounds  of  mercuric  sulphid  with  other  mercury  salts 
present.  Eventually  the  mass  of  sulphid  overcomes  the  other 
salts  and  a  pure  black  precipitate  of  mercuric  sulphid  remains. 
This  black  amorphous  sulphid  is  a  less  stable  modification,  which 
can  be  made  to  change  by  sublimation  to  the  permanent  red  crys- 
talline form  known  as  vermillion. 

Mercurous  sulphate,  Hg2SO4,  is  prepared  by  warming  mer- 
cury with  strong  sulphuric  acid.  There  is  evolution  of  sulphur 
dioxid,  and  the  sulphate  is  deposited  as  a  white  powder  of  difficult 
solubility.  This  powder  is  the  starting-point  in  the  manufacture 


MERCURY  313 

of  other  mercury  salts.  It  is  also  used  in  making  standard  electric 
cells. 

Mercuric  sulphate,  HgSO4,  is  formed  when  the  mercurous 
salt  is  heated  with  excess  of  sulphuric  acid.  There  is  evolution 
of  sulphur  dioxid,  and  the  heavy,  white,  crystalline  mercuric  sul- 
phate is  precipitated.  On  treating  this  normal  salt  with  boiling 
water  the  yellow  basic  salt  is  formed,  and  an  acid  salt  remains  in 
solution.  The  basic  salt  has  been  used  in  medicine  under  the 
name  of  Hydrargyri  subsulphas  flavus  or  (oxysulphate  or  turpeth 
mineral}.  Its  formula  is  Hg3SO4(OH)4,  and  it  is  sometimes 
regarded  as  a  compound  of  the  sulphate  and  oxid.  It  is  a  yellow, 
tasteless,  insoluble  powder.  Dose  as  an  emetic:  3  to  5  gr.  (0.2- 

0-33  gm.)- 

Mercurous     Nitrate,     HgNO3,     and     Mercuric     Nitrate, 

Hg(NO3)2.  —  When  mercury  is  dissolved  in  cold  nitric  acid  with 
excess  of  the  metal,  the  mercurous  salt  is  formed;  if  the  acid  be 
in  excess  and  be  heated,  then  the  mercuric  nitrate  is  the  product. 
The  white  salts  thus  obtained  dissolve  in  water  containing  free 
acid;  but,  without  the  acid,  water  changes  them  to  an  insoluble 
basic  nitrate,  with  the  composition  Hg3(NO3)2(OH)4,  analogous  to 
the  basic  sulphate.  To  prove  that  the  mercuric  salt  is  the  product, 
dilute  and  add  hydrochloric  acid.  If  any  mercurous  nitrate 
be  present,  the  white  mercurous  chlorid  will  be  precipitated  and 
more  hot  nitric  acid  is  needed. 

Liquor  hydrargyri  nitratis  is  a  liquid  containing  mercuric  nitrate 
60  per  cent,  and  free  nitric  acid  n  per  cent.  It  is  a  colorless, 
heavy  liquid  with  a  strongly  acid  reaction,  used  as  an  escharotic. 
Unguentum  hydrargyri  nitratis  is  its  ointment,  having  a  bright 
citrine  color. 

Ammoniated  Mercury  (NH2HgCl)  (Hydrargyrum  Ammonia- 
tum,  While  Precipitate}.  —  If  mercuric  chlorid  be  added  to  cold 
ammonium  hydroxid  in  excess,  a  white  precipitate  of  mercuric 
ammonium  chlorid  forms. 


This  tasteless  and  insoluble  powder  is  dissipated  by  heat  with- 
out melting.  It  is  ammonium  chlorid,  NH4C1,  in  which  two 
hydrogen  atoms  have  been  replaced  by  mercury.  A  lo-per  cent. 
ointment  is  official  under  the  name  of  unguentum  hydrargyri 
ammoniati. 

When  a  mercurous  salt  is  added  to  ammonium  hydroxid  a 
black  precipitate  falls  which  may  contain  metallic  mercury  with 
the  salt  described  above.  It  is  probably  a  complex  mixture  in 
which  there  exists  some  mercurous  chloramid,  NH2Hg2Cl.  By 


314  THE    METALS 

the  same  reaction  paper  wet  with  mercurous  nitrate  is  blackened 
by  the  vapor  of  ammonia. 

Toxicology   of   Salts   of   Mercury.— Symptoms.— Corrosive 

sublimate  is  the  salt  to  which  mercury  poisoning  can  be  most 
frequently  attributed.  However  administered,  it  is  a  very  active 
gastro-intestinal  irritant.  When  taken  by  the  mouth,  the  symp- 
toms usually  begin  within  a  few  minutes.  The  onset  is  never 
delayed  half  an  hour.  There  are  an  acrid,  metallic  taste,  con- 
striction of  the  throat,  retching,  and  a  burning  sensation  in  the 
gullet  and  stomach.  A  white  coating  forms  at  once  on  the  shriv- 
eled lining  of  the  mouth,  the  inflammation  of  the  throat  may 
involve  the  larynx,  and  acute  swelling  of  the  glottis  may  cause 
asphyxia.  The  pain  in  the  stomach  is  so  severe  as  to  cause  faint- 
ing. It  comes  on  promptly,  attended  by  nausea  and  vomiting 
of  material  streaked  with  blood,  and  later  on  purging  and  strain- 
ing with  bloody  stools.  Free  hemorrhages  occur  from  the  stomach, 
bowels,  or  other  outlet.  The  urine  is  scanty  or  suppressed, 
the  temperature  may  be  febrile  or  subnormal,  the  respiration 
difficult,  the  pulse  thready  and  irregular.  Death  is  preceded  by 
collapse,  unconsciousness,  or  convulsions. 

Fatal  results  have  followed  the  application  of  an  alcoholic 
solution  of  corrosive  sublimate  (80  gr.  to  i  oz.)  to  the  scalp  for 
ringworm.  Two  cases  resulted  fatally,  from  poisoning,  by  the 
external  application  of  an  ointment  of  corrosive  sublimate  to 
cure  the  itch.  In  these  cases,  besides  the  painful  local  inflam- 
mation, in  a  few  days  gastro-intestinal  symptoms  appeared,  such 
as  vomiting  and  purging  with  tenesmus.  In  addition,  there  were 
stomatitis,  fetid  breath,  fever,  scanty  urine,  and  collapse.  When 
the  poison  is  absorbed  as  a  result  of  irrigation  of  wounds  of  the 
vagina,  uterus,  or  abscess  cavities,  the  digestive  organs  also  are 
profoundly  affected.  An  early  effect  is  serous  diarrhea,  which 
afterward  becomes  bloody,  attended  by  colic  and  tenesmus,  nausea, 
and  vomiting.  The  urine  is  usually  albuminous,  containing 
epithelial  cells  and  granular  casts.  While  there  may  be  severe 
headache,  insomnia,  dimness  of  vision,  and  transient  disturbance 
of  the  intellect,  the  mind  is  usually  clear  to  the  end.  The  pulse 
grows  weaker,  the  pupils  contract,  the  temperature  falls,  and 
sometimes  an  intense  erythema  appears.  The  great  frequency 
of  deaths  from  antiseptic  irrigations  with  corrosive  sublimate 
pleads  for  its  disuse  in  obstetric  practice. 

Fatal  Dose. — It  is  probable  that  fatal  consequences  would 
follow  doses  of  3  to  5  gr.  of  corrosive  sublimate.  Recovery  has 
resulted  after  the  administration  of  100  gr.  under  prompt  treat- 
ment by  milk,  eggs,  and  emetics.  White  precipitate  or  mercur- 
ammonium  chlorid  was  at  one  time  regarded  as  non-poisonous. 


MERCURY  315 

Several  deaths  from  it  have  been  reported — one  from  35  gr.  Red 
precipitate  has  caused  acute  gastro-intestinal  irritation  when  given 
in  doses  of  2  dr.  or  more.  Acid  mercuric  nitrate,  intended  to 
be  used  externally  only  as  an  escharotic,  has  been  followed  by 
death  after  such  use,  and  also  when  administered  internally.  The 
yellow  subsulphate,  or  turpeth  mineral,  used  in  the  treatment  of 
croup,  has  often  caused  alarming  symptoms.  Two  doses  of  3  gr. 
each  have  been  sufficient  to  cause  death. 

Fatal  Period. — Death  may  occur  in  half  an  hour,  but  com- 
monly life  is  prolonged  for  from  two  to  four  days,  and  it  may  last 
into  the  second  week. 

Treatment. — Vomiting  should  be  encouraged  by  large  drafts 
of  milk  containing  emetics.  The  casein,  like  all  albuminous  com- 
pounds, acts  as  an  antidote.  The  most  convenient  protein  should 
be  given  freely.  This  may  be  raw  eggs,  flour  paste  for  its  gluten, 
or  blood  from  a  freshly  killed  fowl,  given  in  milk  or  water.  Mag- 
nesia would  prove  beneficial  by  conversion  of  the  corrosive  sub- 
limate to  a  less  injurious  compound.  It  should  not  be  forgotten 
that  the  albuminate  of  mercury  may  dissolve  in  excess  of  albumin; 
hence  emetics  are  called  for  after  the  antidote  has  been  given. 
The  pain,  purging,  and  tenesmus  will  require  such  treatment  as 
is  usually  given  for  gastro-enteritis. 

Postmortem  Appearances. — Some  parts  of  the  alimentary 
canal  are  sure  to  show  inflammatory  change.  In  the  mouth,  throat, 
and  stomach  there  will  be  patches  of  congestion  and  erosion,  or  the 
intestines,  especially  the  colon,  may  be  the  seat  of  inflammation. 
Eventually  the  kidneys  swell  and  take  on  acute  inflammation. 

Even  when  death  has  occurred  from  absorption  of  the  poison 
as  a  result  of  application  to  the  skin  or  irrigation  of  abscesses  or 
of  wounds,  or  of  the  uterus  and  vagina,  the  most  important  lesions 
are  in  the  digestive  tract,  especially  the  colon.  There  is  hyperemia 
of  the  mucous  membrane,  of  the  colon,  with  easy  detachment  of 
the  epithelium,  patches  of  superficial  necrosis  in  some  parts,  and 
in  others  a  diphtheritic  coating  infiltrating  the  deeper  layers.  The 
kidneys  show  a  characteristic  acute  parenchymatous  nephritis. 
In  some  cases  the  peritoneum  is  slightly  injected.  The  liver 
shows  no  marked  lesion,  but  is  generally  pale  and  anemic.  The 
other  organs  may  be  unaffected. 

Chronic  Poisoning  or  Mercurialism. — The  operatives  in 
quicksilver  mines,  mirror-makers,  fire  gilders,  thermometer-  and 
barometer-makers,  furriers,  and  hatters  are  liable  to  a  chronic 
disease  ending  in  paralysis,  brought  about  by  the  daily  intro- 
duction and  accumulation  in  the  system  of  minute  doses  of  mer- 
cury. Some  of  the  milder  symptoms  have  been  induced  by  the 
incautious  use  of  mercurials  in  the  treatment  of  secondary  syphilis, 


316  THE    METALS 

and  by  repeated  applications  to  the  skin  of  a  weak  lotion  of  cor- 
rosive sublimate  for  cosmetic  purposes. 

The  symptoms  shown  in  chronic  mercurial  poisoning  are  often 
quite  complex.  Ptyalism,  or  salivation,  is  usually  present;  the 
secretion  of  saliva  is  profuse,  and  is  attended  with  swelling  and 
tenderness  in  the  salivary  glands;  the  gums  become  red,  spongy, 
and  tender,  with  occasionally  a  blue  line  near  the  teeth;  the  tongue 
is  swollen  and  painful;  ulcers  form  in  the  mouth,  and  the  breath 
is  very  fetid.  The  teeth  are  loosened,  and  the  alveolar  processes 
sometimes  become  the  seat  of  acute  periostitis.  There  is  usually 
loss  of  appetite,  with  attacks  of  nausea  and  vomiting.  In  some 
cases  colic  and  diarrhea  are  present.  Soon  supervene  depressed 
energies,  loss  of  weight,  anemia,  and  a  peculiar  cachexia  with 
eruptions  of  erythema  or  eczema.  The  nervous  system  is  even- 
tually involved,  showing  attacks  of  cerebral  excitability  and 
insomnia,  or  perhaps  hebetude  of  mind.  In  the  end  a  peculiar 
fine  tremor  spreads  from  the  tongue  and  face  to  the  upper  and 
lower  extremities.  The  tendency  of  these  tremblings  is  to  progress 
from  the  jerky  and  intermittent  form,  brought  on  by  excitement 
or  exertion,  to  the  continuous,  which  lessens  only  during  sleep. 
The  muscles  grow  weaker,  without  loss  of  electrocontractility. 

Disturbances  of  sensation  are  common;  sometimes  neuralgia 
is  a  symptom,  at  times  appearing  as  numbness  and  tingling  in 
anesthetic  patches.  Affections  of  sight  and  hearing  are  not 
infrequent. 

The  postmortem  appearances  indicate  that  mercury,  like  arsenic 
and  lead,  has  the  power  to  excite  a  progressive  peripheral  neuritis. 
The  localized  mercurial  palsies  differ  from  the  lead  palsies  in  that 
the  electrocontractility  is  unimpaired,  there  is  no  atrophy,  and 
the  tendon  reflexes  persist.  The  characteristic  nerve  lesion  is  a 
destruction  of  the  myelin,  with  preservation  of  the  axis  cylinder. 
The  trophic  changes  are  pigmentary  and  peri-axile. 

Treatment  of  Chronic  Mercurialism. — Improvement  usually 
follows  removal  of  the  patient  from  the  surroundings  where  he  was 
exposed  to  the  poison.  Although  elimination  of  a  single  dose  is 
usually  complete  in  a  few  days  by  means  of  the  salivary  glands, 
the  kidneys,  the  intestines,  and  in  less  degree  by  the  sweat  and 
milk,  still  if  the  period  of  absorption  has  been  prolonged,  as  it  is 
in  chronic  mercurialism,  some  portion  of  the  poison  may  be 
retained,  combined  with  albuminous  bodies  in  an  inactive  state 
for  many  months.  To  stimulate  the  process  of  elimination  and 
to  secure  the  oxidation  of  the  albuminous  compound  so  as  to  set 
free  the  mercury,  the  bowels  should  be  kept  opened,  the  action 
of  the  skin  promoted  by  warm  baths,  and  the  best  hygienic  and 
tonic  regimen  instituted.  It  is  customary  to  administer  potas- 


MERCURY  317 

slum  iodid  in  small  doses  in  the  belief  that  it  changes  the  deposited 
poison  into  mercuric  iodid,  which  is  soluble  in  excess  of  the  potas- 
sium salt,  and  is  by  this  means  conveyed  into  the  excretory  fluids. 
For  the  paralysis,  massage  and  electricity  are  indicated;  for  the 
salivation,  mild  mouth-washes  of  potassium  chlorate  or  borax 
are  called  for. 

Tests.— Sublimation  Test  for  Compounds  in  the  Solid 
State. — The  suspected  solid  is  first  thoroughly  dried,  mixed  with 
dry  sodium  carbonate,  and  heated  gently  in  a  reduction  tube.  A 
shining  ring  forms  on  the  inside  of  the  tube  in  the  cooler  part. 
A  lens  resolves  this  sublimate  into  minute  shining  spheres  of 
metallic  mercury.  The  corresponding  sublimate  of  arsenic  and 


FIG.  70. — Sublimate  of  metallic  mercury,  magnified. 

antimony  are  not  of  this  shape.  Rubbed  with  a  glass  rod,  these 
globules  run  together  into  larger  rounded  masses.  A  few  scales 
of  iodin  left  in  the  closed  tube  for  a  few  hours  will  vaporize  and 
convert  the  mercury  into  a  film  of  yellow,  and  later  of  red,  mercuric 
iodid.  If  this  test  be  done  in  a  small  subliming  cell,  such  as  is 
described  under  Arsenic  (p.  277),  and  collected  on  a  slide  for 
microscopic  examination,  it  is  of  very  great  delicacy  (Fig.  70). 

Hydrogen  Sulphid  Test. — A  solution  of  a  mercurial  salt  acidu- 
lated with  hydrochloric  acid  yields  a  black  precipitate  when 
treated  with  a  stream  of  hydrogen  sulphid.  The  formation  of 
the  mercuric  sulphid  through  intermediate  stages  is  shown  if  the 


318  THE    METALS 

tested  solution  is  strong;  the  precipitate  becomes  successively 
yellowish  white,  dark  yellow,  orange,  brown,  and  black.  The 
precipitate  is  insoluble  in  caustic  alkalis,  alkaline  sulphids,  and 
nitric  or  hydrochloric  acids.  It  can  be  identified  by  yielding  the 
globular  sublimate  when  dried  and  heated  with  sodium  carbonate, 
as  directed  above.  By  drying  the  sulphid  in  an  air  oven  and 
weighing,  the  quantity  of  mercury  can  be  calculated. 

Reinsch's  Test. — The  procedure  is  the  same  as  that  given 
under  Arsenic  (p.  277).  A  strip  of  bright,  pure  copper-foil  will 
receive  a  gray  or  silvery  deposit  in  a  few  minutes  from  a  boiling 
mercurial  solution  acidified  with  hydrochloric  acid.  Having 
carefully  washed  the  coated  copper  in  water  and  dried  it,  the 
slip  should  be  heated  in  a  small  dry  reduction  tube,  and  the  re- 
sulting sublimate  examined  for  globules,  as  stated  above,  and 
tested  with  free  iodin. 

Fallacies. — This  test  yields  a  metallic  deposit  on  copper  from 
arsenic,  antimony,  bismuth,  silver,  and  some  rarer  metals.  Coat- 
ings of  arsenic,  antimony,  and  mercury  are  the  only  ones  that 
give  a  sublimate  when  heated  in  a  reduction  tube. 

Mercury  is  peculiar  in  its  opaque  globular  form  and  the  bright 
high  lights  under  reflected  light  (Fig.  70). 

Delicacy. — Using  capillary  reduction  tubes  of  peculiar  con- 
struction, characteristic  globules  have  been  obtained  from  g  o  o1*)  o  o 
gr.  of  corrosive  sublimate;  under  ordinary  manipulation  unnnro  gr- 
is  nearer  to  the  limit  of  delicacy. 

Galvanic  Gold  Test. — A  band  of  goldfoil  is  wrapped  about  a 
strip  of  thin  zinc,  leaving  some  zinc  exposed,  thus  making  a  gal- 
vanic couple.  Having  acidulated  the  suspected  liquid  with  hy- 
drochloric acid  and  warmed  it,  the  two  metals  are  hung  in  it  for 
several  hours.  A  silvery  deposit  on  the  gold  indicates  mercury. 
After  washing  the  gold  successively  in  water,  alcohol,  and  ether, 
it  may  be  heated  in  a  reduction  tube  and  the  sublimate  of  mer- 
curial globules  produced  may  be  identified,  as  stated  under  sub- 
limation test. 

Potassium  lodid  Test. — On  adding  potassium  iodid  to  a  solu- 
tion of  corrosive  sublimate  or  other  mercuric  salt  a  precipitate 
falls,  at  first  yellow,  but  rapidly  changing  to  red  mercuric  iodid. 
This  will  dissolve  in  excess  of  the  potassium  iodid. 

Distribution  in  the  Tissues.— Riederen  gave  to  a  dog  in 
thirty-one  days  2.789  gm.  of  calomel'  (2.368  gm.  Hg.).  By  anal- 
ysis he  recovered  2.2  gm.  of  mercuric  sulphid  (1.9  gm.  Hg.),  of 
which  there  were  in  the  feces  95  per  cent.,  or  2.1175  gm-5  *n  tne 
urine,  0.055;  m  the  brain,  heart,  lungs,  spleen,  pancreas,  kidneys, 
scrotum,  and  penis,  0.009;  in  the  liver,  0.014;  in  the  muscles, 
0.0114.  If  the  poison  find  access  to  the  body  by  external  appli- 


MERCURY  319 

cation  or  by  irrigation  of  other  cavities  than  the  alimentary  tract, 
it  should  be  looked  for  in  the  liver,  the  urine,  and  the  kidneys. 
Other  cases  have  been  reported  which  established  the  fact  that 
in  a  few  days  the  whole  amount  of  one  poisonous  dose  given  by 
the  mouth  may  escape  from  the  body. 

There  is  liability  to  error  if  the  analyst  loses  sight  of  the  well- 
known  fact  that  traces  of  mercury  are  very  commonly  found  in 
the  stomach,  bowels,  liver,  kidneys,  and  other  organs  of  the  cadaver 
with  no  history  of  recent  dosage  from  the  poison.  These  are 
probably  accumulations  from  small  non-poisonous  doses  of 
blue  mass  or  calomel,  or  perhaps  vestiges  of  a  previous  mercurial 
treatment  of  syphilis. 

Detection. — A  ready,  casual  examination  can  be  made  of 
the  vomited  matters  or  urine  by  decanting  the  liquid  portion, 
evaporating  it  to  dryness,  treating  with  pure  hydrochloric  acid, 
and  applying  Reinsch's  test,  the  galvanic  gold  test,  or  the  elec- 
trolytic test. 

Separation  from  the  tissues  or  other  organic  matter  is 
accomplished  by  the  systematic  method  referred  to  under  Arsenic. 
To  disintegrate  the  organic  matter  thoroughly  it  must  be  finely 
minced  and  heated  on  a  water-bath  for  some  time  with  equal 
parts  of  water  and  hydrochloric  acid,  while  potassium  chlorate 
is  added  in  small  amounts  until  a  clear  solution  is  made.  After 
filtration  the  solution  is  heated  gently  to  expel  the  chlorin  and  a 
stream  of  hydrogen  sulphid  is  passed  until  the  metal  is  all  pre- 
cipitated as  sulphid.  A  portion  of  this  sulphid  may  be  tested  by 
reduction  and  sublimation,  or  it  may  be  dissolved  by  gentle  heat 
in  nitrohydrochloric  acid,  the  solution  evaporated  to  dryness  on 
a  water-bath,  redissolved  in  warm  water,  and  the  above  tests  be 
applied  or  the  mercury  separated  by  electrolysis. 

Electrolysis  may  be  performed  conveniently  by  the  method  of 
Mann.  The  suspected  solution  is  put  in  a  glass  cell  having  a 
bottom  of  parchment-paper,  and  immersed  to  a  common  level  in 
an  outer  vessel  of  water  acidulated  with  sulphuric  acid.  The 
cathode  of  a  battery  of  four  Grove  cells,  made  of  a  slip  of  gold- 
foil,  is  fixed  into  the  inner  vessel  near  to  and  parallel  with  the 
bottom.  In  the  outer  liquid  is  set  the  anode,  a  strip  of  platinum 
opposite  to  the  cathode.  After  the  current  has  passed  six  hours, 
the  gold  coated  with  mercury  is  washed  successively  with  water, 
alcohol,  and  ether,  and  weighed.  By  heating  the  gold-foil  in  a 
hard  glass  open  tube  of  known  weight  the  mercury  sublimes  and 
is  deposited  on  the  tube. 

Quantitative  determination  may  be  made  by  finding  the  loss 
of  weight  of  the  gold-foil  carrying  a  film  of  mercury  when  heated 
as  above  described.  This  gives  the  weight  of  mercury  in  the 


320  THE    METALS 

portion  of  fluid  tested;  it  can  be  controlled  by  calculating  the 
increase  of  weight  in  the  tube.  Instead  of  using  electrolysis,  the 
amount  of  corrosive  chlorid  present  in  any  fluid  in  which  mercury 
is  sought  may  be  determined  simply  by  boiling  the  materials  in 
water,  straining,  filtering,  and  agitation  of  the  filtrate  with  ether, 
separation,  and  evaporation  of  the  ethereal  extract.  The  dried 
residue  dissolved  in  water  may  be  precipitated  with  volumetric 
solution  of  silver  nitrate,  the  chlorin  estimated,  and  from  this  the 
weight  of  mercuric  chlorid  calculated. 

Urine  examination  may  be  made  by  electrolysis,  Reinsch's 
test,  or  by  Mayer's  method,  which  follows:  Having  evaporated  the 
urine  to  dryness,  the  residue,  mixed  with  quicklime  and  slaked 
lime,  is  heated  in  a  combustion  tube,  condensing  the  mercury  on 
the  cooler  part. 

Rapid  Method. — Separate  the  mercury  from  organic  combina- 
tions by  heating  to  the  boiling-point  in  a  porcelain  dish  a  mixture 
of  20  fl.  oz.  (600  c.c.)  of  urine  with  4  fl.  oz.  (100  c.c.)  of  hydro- 
chloric acid  and  7  gr.  (0.50  gm.)  of  potassium  chlorate.  Before 
it  has  cooled  it  is  poured  through  a  filter  (if  turbid)  into  a  funnel 
having  a  stopcock,  previously  adjusted  to  permit  100  c.c.  to  pass 
in  one  minute.  The  end  of  the  funnel  rests  in  a  smaller  funnel- 
tube,  the  outlet  of  which  has  been  heated  and  drawn  into  a  fine 
opening.  Inside  this  narrowed  tube  has  been  placed  a  small 
spiral  of  bright  copper-foil.  Having  passed  all  the  urine  through 
the  funnels  and  over  the  copper,  the  operation  is  repeated  six 
times,  keeping  the  urine  hot.  If  mercury  be  deposited,  the  cop- 
per will  change  color.  The  copper  spiral  is  taken  out  with  for- 
ceps, washed  in  water,  alcohol,  and  ether,  dried,  and  heated  in  a 
narrow  tube.  The  mercury  vaporizes  and  is  condensed  as  glob- 
ules on  the  glass. 

LEAD  (Plumbum) 
Symbol,  Pb.     Atomic  weight,  207. 

There  are  numerous  compounds  of  lead  in  nature,  the  most 
important  being  galena,  the  sulphid,  PbS.  This  is  roasted  till 
oxidized  and  the  oxid  is  reduced  with  carbon. 

Properties. — Lead  is  a  soft  bluish-white  metal,  heavy,  but  of 
low  melting-point,  325°  C.  (617°  F.).  Freshly  cut  surfaces  have 
a  brilliant  luster  which  is  soon  lost,  a  superficial  layer  of  oxid  being 
deposited  by  the  action  of  the  air.  The  softness,  pliability,  and 
low  melting-point  of  lead  make  it  a  convenient  material  for 
plumber's  pipe.  Soft  solder  is  an  alloy  of  lead  and  tin.  Type  metal 
contains  lead,  tin,  and  antimony.  Pewter  contains  lead  and  tin. 
Metallic  lead  dissolves  freely  in  nitric  acid,  sparingly  in  strong 
sulphuric  acid  when  hot,  but  not  in  dilute  or  cold  sulphuric  acid, 


LEAD  321 

nor  practically  in  hydrochloric  acid.  The  metal,  when  embedded 
in  the  tissues  as  a  bullet,  exerts  no  local  specific  action,  being 
insoluble  in  the  fluids  there.  While  not  soluble  in  pure  water, 
the  ordinary  water  served  in  plumber's  pipes  contains  enough  free 
oxygen  to  oxidize  a  fresh  lead  surface,  which  may  then  form  a 
soluble  bicarbonate  by  the  aid  of  the  carbon  dioxid  present.  A 
portion  of  it  finally  forms  a  crust  of  insoluble  hydrated  oxycar- 
bonate,  which  prevents  further  action.  While  silicates,  sulphates, 
and  carbonates  tend  to  prevent  the  corrosive  action  of  water, 
it  is  increased  by  nitrites,  nitrates,  and  chlorids.  Hence,  a  hard 
water  supply  is  less  dangerous  when  served  in  lead  pipes  than  a 
"soft"  or  purer  article. 

The  Ions  of  Lead. — The  element  itself  forms  a  bivalent  cation, 
Pb",  called  plumbion,  and  an  unstable  quadrivalent,  cation, — 
Pb"**.  Plumbion  is  without  color  and  is  a  potent  poison.  When 
lead  is  acted  upon  by  air  and  water  a  white  precipitate  of  lead 
hydroxid,  Pb(OH)2,  forms  which  behaves  toward  alkalis  just  as 
does  alumina — that  is,  it  dissolves  in  excess  of  alkali,  but  not 
in  ammonia.  With  those  bases  it  forms  soluble  plumbites,  the 
hydroxid  having  split  off  hydrogen  to  form  complex  anions,  such 
as  (PbO2)"  and  (HPbO2)'.  A  hypothetic  hydroxid,  Pb(OH)4,  is 
supposed  to  contain  the  quadrivalent  anion  (PbO4)"",  and  has 
received  the  name  of  normal  plumbic  acid.  This,  by  the  loss  of 
water,  forms  metaplumbic  acid,  H2PbO3.  With  calcium  the 
former  makes  calcium  plumbate,  Ca2PbO4;  with  sodium  the  latter 
makes  sodium  metaplumbate,  Na2PbO3.  These  acids  combine 
with  lead  itself  to  make  Pb2PbO4  or  Pb3O4,  minium,  and  PbPbO3 
or  Pb2O3,  the  sesquioxid. 

Lead  Oxid  (PbO)  (Plumbi  Oxidum,  Litharge).— When  air 
or  oxygen  is  caused  to  pass  over  salts  of  lead,  heated  or  melted 
lead,  a  yellow  powder  forms.  This  powder,  fused  at  a  higher 
temperature,  forms  yellowish  crystalline  scales  of  PbO  called 
commercially  litharge.  Continued  gentle  heat  in  air  changes  it 
to  a  bright-red  powder,  Pb3O4,  used  as  a  pigment  under  the  names 
red  lead,  or  minium.  If  the  red  lead  be  oxidized  by  heating  with 
nitric  acid,  a  dark-brown  powder  forms,  the  dioxid  or  peroxid, 
PbO2.  The  oxid,  PbO,  dissolves  sparingly  in  water,  imparting 
an  alkaline  reaction,  due  to  the  formation  of  lead  hydroxid,  Pb 
(OH)2.  It  is  strongly  basic,  decomposing  alkaline  salts.  With 
thi  fatty  acids  of  oils  it  unites  to  form  lead  soaps,  the  most  im- 
p  /rtant  jf  which  is  lead  oleate  or  emplastrum  plumbi.  Heated 
with  milk  of  lime  its  hydroxid  develops  acid  properties  as  H2PbO2, 
forming  a  soluble  crystalline  calcium  plumbite,  CaPbO2,  used  as  a 
hair  dye. 

Lead  dioxid   (PbO2)    (peroxid,   brown  oxid,  puce   oxid)   is   an 

21 


322  THE    METALS 

insoluble  dark  brown  powder,  readily  yielding  half  its  oxygen  when 
heated.  It  is  much  used  in  the  laboratory  as  an  oxidizing  reagent. 

Lead  chlorid,  PbCl2,  is  formed  by  a  reaction  between  a  sol- 
uble lead  salt  and  a  chlorid;  or  whenever  plumbion  and  chloridion 
are  brought  together  in  concentrated  solution.  It  is  a  white 
crystal,  very  sparingly  soluble.  Uniting  with  lead  oxid  it  forms 
several  basic  or  oxychlorids  of  a  yellow  color,  which  are  used  as 
pigments  under  the  names  of  Turner's,  Naples,  Verona,  or  Paris 
yellow. 

Lead  nitrate,  Pb(NO3)2,  is  prepared  by  dissolving  lead  or 
lead  oxid  in  dilute  nitric  acid.  While  readily  soluble  in  water  it 
is  very  sparingly  soluble  in  strong  nitric  acid.  It  is  white  and 
sweetish,  the  after-taste  being  metallic  and  astringent. 

Lead  sulphate,  PbSO4,  is  formed  when  hot  strong  sulphuric 
acid  acts  on  lead.  It  is  the  heavy  white  precipitate  that  falls 
when  plumbion,  Pb",  meets  sulphanion,  (SO4)",  as  happens  when 
sodium  or  magnesium  sulphate  is  given  as  an  antidote  to  lead- 
poisoning,  thus: 

Pb",  (NO,)',  (NO,)',       +        K-,  K-,  (S04)"       = 

K-,  (N03/         +         K',(N03)'        +         PbS04. 

It  is  sometimes  used  to  give  weight  or  body  to  white  silk,  and 
from  this  fabric  it  may  be  taken  accidentally  by  seamstresses. 

The  storage  battery  or  accumulator  contains  a  plate  of  lead  and 
one  of  lead  dioxid,  PbO2,  immersed  in  sulphuric  acid.  A  charging 
electric  current,  having  been  sent  through  the  cell,  has  accumulated 
as  intrinsic  or  chemical  energy  in  the  Pb"",  O2".  When  the 
circuit  is  closed  this  stored  energy  flows  back  as  a  discharging 
electric  current  while  the  two  plates  are  both  converted  to  lead 
sulphate.  The  quadrivalent  Pb""  in  the  PbO2  gives  up  two 
charges  of  electricity  to  become  the  Pb"  in  PbSO4.  The  battery 
is  restored  by  a  charging  current  which  reverses  the  reaction, 
raising  the  Pb"  to  its  former  state  of  Pb"". 

Lead  Carbonate  (2(PbCO3).  Pb(OH)2)  (PlumU  Carbonas, 
White  Lead}. — The  paint  known  variously  as  white  lead,  flake 
white,  and  mineral  white  is  a  mixture  of  lead  hydroxid  and  neu- 
tral lead  carbonate.  It  is  present  in  the  official  ointment  of  lead 
carbonate.  It  is  the  white  precipitate  formed  when  plumbion, 
Pb",  and  carbanion  (CO3)",  meet  in  the  same  solution.  To 
facilitate  the  reaction  between  lead  oxid  and  carbon  dioxid  the 
vapor  of  acetic  acid  is  used  as  an  intermediary.  First  a  basic 
acetate  is  formed,  and  this  changes  to  the  basic  carbonate.  It  is 
a  smooth,  white,  insoluble,  tasteless  powder,  invaluable  as  a  base 
tor  paints.  Sometimes  it  has  been  used  as  a  cosmetic  with  the 


LEAD 


323 


most  deplorable  consequences.     It  is  the  most  common  cause  of 
chronic  lead-poisoning. 

Lead  chr ornate,  PbCrO4,  is  the  heavy  yellow  precipitate  formed 
when  plumbion,  Pb",  meets  chromanion  (CrO4)". 

Pb",  (NO,)',  (NO,)'        +         K-,  K-,  (Cr04)"        = 
K«,  (NO,)'          +         K-,  (NO,)'          +          PbCr04. 

It  is  an  amorphous,  insoluble  powder  used  as  a  pigment  under 
the  name  chrome  yellow.  The  basic  chromate  is  known  as  chrome 
orange. 

Lead  acetate,  Pb(C2H3O2)23H2O,  plumbi  acetas,  is  made  by 
the  action  of  acetic  acid  on  lead  oxid.  It  occurs  in  white  masses 
of  acicular  crystals.  It  is  soluble  in  water,  and  has  a  taste  at 
first  sweetish,  hence  the  popular  name,  sugar  oj  lead,  but  later 
the  taste  is  styptic  and  metallic  in  character.  It  is  present  in 
pharmaceutic  preparations,  as  a  pill,  with  opium,  a  compound 
suppository  with  opium,  and  an  ointment.  The  subacetate, 
Pb(C2H3O2)2PbO,  made  by  dissolving  the  oxid  in  solutions  of  the 
acetate,  is  present  (25  per  cent.)  in  liquor  plumbi  subacetatis,  "  Goul- 
ard's Extract;"  in  a  dilute  form  (i  per  cent.)  in  liquor  plumbi 
subacetatis  dilutus  (lead-water),  and  in  the  compound  cerate  or 
Goulard's  cerate.  Clear  solutions  soon  turn  white  from  the  action 
of  carbon  dioxid  in  the  air.  This  tendency  is  arrested  by  adding 
acetic  acid  in  excess.  This  property  is  not  shared  by  the  solution 
of  the  nitrate,  which  keeps  clear. 

Toxicology  of  Lead  Salts.— In  spite  of  its  great  frequency, 
lead-poisoning  rarely  figures  in  the  courts,  owing  to  the  fact  that 
most  of  the  cases  are  due  to  slow  absorption  of  minute  quantities, 
exposure  to  which  is  an  incident  of  certain  industries  dealing  with 
lead  or  its  compounds.  The  fatal  cases  represent  but  a  small 
fraction  of  the  persons  who,  from  numberless  causes,  suffer  from 
degrees  of  chronic  poisoning  more  or  less  serious,  but  not  ending 
in  death. 

Poisonous  Salts. — The  salt  which  is  of  most  importance  in 
acute  poisoning  is  lead  acetate,  while  chronic  poisoning  is  most 
frequently  caused  by  lead  carbonate. 

The  subacetate  of  lead  present  in  Goulard's  extract  has  very 
much  the  same  effect  as  the  acetate,  but  greater  in  degree,  as  it 
contains  more  lead.  Lead  chromate  (chrome  yellow),  lead  oxids 
(litharge  and  red  lead),  and  finely  divided  metallic  lead,  while  not 
soluble  in  pure  water,  dissolve  in  certain  natural  waters  containing 
nitrates  and  nitrites  and  in  the  dilute  vegetable  acids  of  food  and 
in  the  gastric  juice,  are  absorbed  in  the  intestines,  deposited  in 
various  tissues,  and  exert  a  slowly  cumulative  poisonous  action. 


324  THE    METALS 

Ledoyen's  Disinfectant,"  containing  lead  nitrate,  and  "Tur- 
ner's yellow,"  or  the  oxychlorid — in  fact,  all  the  salts  of  lead 
are  poisonous,  except  perhaps  the  sulphid  and  sulphocyanate. 

Acute  Lead-poisoning. — Symptoms. — At  first  they  are  such  as 
result  from  a  local  irritant,  and  are  less  likely  to  be  fatal  from  a 
single  large  dose  than  from  the  same  amount  taken  in  fractions 
at  intervals.  In  a  few  minutes  a  metallic  taste  is  perceived,  and 
soon  afterward  the  mouth  and  throat  feel  dry  and  burn.  Retching 
and  vomiting  may  appear  in  less  than  half  an  hour  and  prove 
obstinate  and  persistent.  Abdominal  pains  come  on  in  colicky 
cramps,  relieved  by  pressure.  Usually  the  bowels  are  consti- 
pated; occasionally  the  stools  are  bloody,  and  at  a  later  date  they 
are  dark  from  lead  sulphid.  The  urine  is  scanty,  the  face  anxious, 
the  skin  dry,  the  breath  fetid,  and  the  tongue  coated.  While  the 
brain  is  clear,  the  involvement  of  the  nervous  system  is  indicated 
by  the  headache,  the  pain  and  cramps  in  the  legs,  and  the  numb- 
ness and  local  palsies  which  appear  a  few  hours  later.  After 
a  few  days  in  some  cases  a  blue  line  is  seen  on  the  gums. 

Fatal  Dose. — It  is  not  known  what  single  dose  of  lead  acetate 
would  prove  fatal.  Since  recovery  has  taken  place  in  3  cases 
after  taking  i  oz.  (28.3  gm.)  of  the  acetate,  it  would  seem  that  the 
fatal  amount  must  be  greater  when  that  salt  is  the  poison.  It  is 
probable  that  the  fatal  dose  of  the  carbonate  would  be  somewhat 
less  than  that  of  the  acetate,  though  the  course  of  the  symptoms 
would  be  slower. 

Fatal  Period. — While  death  from  the  acute  form  is  very  rare, 
23  cases  have  been  collected.  It  may  occur  from  prostration  as 
early  as  the  second  or  third  day. 

Treatment. — The  first  indication  is  the  washing-out  of  the 
stomach  by  a  tube  or  pump,  using  a  solution  of  sulphates  of  magne- 
sium or  sodium.  In  the  absence  of  the  tube  an  emetic  dose  of 
alum  (a  soluble  sulphate)  would  be  serviceable.  When  the 
stomach  is  quiet,  the  remainder  of  the  poison  can  be  neutralized 
and  the  bowels  evacuated  by  £  oz.  of  magnesium  sulphate  (Epsom 
salt).  To  check  vomiting  and  colic  the  best  reliance  is  on  hypo- 
dermic injections  of  morphin  and  atropin. 

Postmortem  Appearances. — In  the  few  autopsies  which  have 
been  held  in  acute  lead-poisoning  indications  have  been  found  of 
gastro-intestinal  inflammation.  When  life  has  been  prolonged 
until  systemic  symptoms  appear,  lesions  have  been  found  in  the 
liver  and  kidneys. 

Chronic  Lead-poisoning  (Plumbism,  Saturnine  Intoxication}. — 
Judging  by  the  cases  reported  in  the  medical  journals,  chronic 
poisoning  is  of  very  common  occurrence.  In  the  vast  majority 
the  lead  enters  the  body  by  accident,  as  a  result  of  its  use  in  cer- 


LEAD  325 

tain  industries;  in  a  certain  proportion  it  is  caused  by  contamina- 
tion of  food  and  drink.  In  these  cases  the  amount  of  lead  in  each 
dose  is  so  small  as  to  escape  detection,  but,  owing  to  its  extra- 
ordinary cumulative  action,  in  time  a  sufficient  quantity  finds 
lodgment  in  different  organs  to  produce  widespread  damage. 

Injurious  Industries. — Operatives  in  the  metal  are  liable  to 
have  it  introduced  by  inhalation,  by  dust  particles  getting  in  the 
hair,  beard,  or  clothing,  and  indirectly  into  food  and  drink,  and 
possibly  through  the  skin.  In  this  way  many  cases  have  been 
caused  in  plumbers,  smelters,  type-founders,  compositors,  shot- 
makers,  file-cutters,  lead-foil  workers,  etc.  It  is  even  more  com- 
mon in  those  who  work  in  the  lead  salts  used  for  colors,  such  as 
color-grinders,  white-  and  red-lead  makers,  japanners,  enamelers, 
lapidaries,  potters,  combers  of  yarn  dyed  with  chrome  yellow,  and 
workers  on  the  lead  plates  of  electric  accumulators. 

Food  Contamination. — As  lead  is  slightly  soluble  in  water  con- 
taining certain  salts  and  gases  (see  p.  321),  its  widespread  use  for 
pipes  in  which  beverages  are  kept  standing  over  night  causes  it  to 
be  introduced  into  drinking  water,  into  ale  and  beer  drawn  from 
the  cellar,  and  into  seltzer-water  kept  in  siphons.  Lead  oxid  is 
largely  used  to  make  a  glaze  on  pottery.  From  this  it  may  be 
dissolved  by  acid  foods,  as  fruit  jellies,  pickles,  vinegar,  and 
lemon-juice.  As  a  constituent  of  solder  and  the  alloy  used  to 
tin  iron  it  finds  access  to  canned  goods  containing  acids. 

As  a  substitute  for  the  yellow  of  egg  in  making  sweet  cakes, 
lead  chromate,  PbCrO4,  under  the  name  "chrome  yellow"  has 
been  used  by  bakers,  with  very  grave  consequences.  An  epidemic 
of  lead-poisoning  in  the  north  of  France,  involving  over  100  persons, 
was  traced  to  lead  in  the  flour  which  was  obtained  by  all  the  suffer- 
ers from  the  same  mill,  contamination  being  due  to  the  elevator 
buckets,  which  were  " tinned"  with  lead. 

Cosmetics. — Most  of  the  lotions  called  "hair-renewers"  are 
preparations  containing  sulphur  with  lead  acetate  or  calcium 
plumbite.  They  do  not  restore  the  natural  pigment,  but  cause 
the  precipitation  of  black  lead  sulphid  in  the  hair  structure,  so 
as  to  simulate  the  natural  color.  The  use  of  "flake  white"  as  a 
cosmetic  has  caused  every  form  of  chronic  lead-poisoning. 

Symptoms  oj  Chronic  Lead-poisoning. — In  this  condition  there 
are  emaciation,  a  feeling  of  "poor  health,"  feeble  appetite,  im- 
paired digestion,  weakened  energies,  low  spirits,  and  more  or  less 
profound  anemia,  as  shown  by  the  pallor.  The  most  characteristic 
symptoms  are  weakness  of  the  forearms  with  dropping  of  the  wrists 
("the  dangles");  colic  with  constipation  ("dry  belly-ache");  a 
blue  line  on  the  gums  and  blue  patches  on  the  cheeks  opposite; 
headaches;  joint  pains  which  may  be  mistaken  for  rheumatism  or 


326  THE    METALS 

gout;  melancholia  or  mania;  convulsions,  sometimes  classed  as 
epileptic.  Albumin  in  the  urine  points  to  the  kidneys  as  the  seat 
of  serious  chronic  disease  caused  by  the  lead.  The  blue  line  on 
the  gums  is  caused  by  the  reaction  between  lead  chlorid  in  the 
gum  and  hydrogen  sulphid  of  decomposed  food  particles  between 
the  teeth.  The  formation  of  the  black  sulphid  is  explained  by 
this  equation: 

PbCl2     +      H2S      =      2HC1     +     PbS. 

The  black  deposit  seen  through  the  opalescent  mucous  mem- 
brane has  a  bluish  color.  Lead  is  found  in  the  urine  of  most  cases 
examined. 

The  fatal  cases  are  characterized  by  convulsions  due  to  brain 
disease.  It  has  been  suggested  that  the  gravity  of  the  nervous 
phenomena  in  poisoning  from  lead  chromate  is  due  in  some  degree 
to  the  chromium  present  in  the  poison. 

~~~"Lead  appears  to  form  some  stable  combination  with  the  sub- 

\      stance  of  the  "nervous  system,  and  induces  thereby  disturbed  func- 

\    tion,  if  not  local  destruction,  of  some  essential  part  of  the  great 

\   centers,  as  well  as  of  the  peripheral  nerves.     In  a  case  of  fatal 

\  lead-poisoning  the  cerebrum  was  found  to  contain  lead  equivalent 

to  ij  gr.  of  sulphate  and  the  cerebellum  about  J  gr.     An  optical 

neuritis  may  cause  visual  disturbances,  but  these  are  sometimes 

due  to  the  retinitis  secondary  to  the  kidney  mischief. 

Treatment  of  Chronic  Poisoning. — By  careful  inquiry  the  source 
of  the  lead  may  be  discovered,  and  the  patient  should  be  guarded 
against  further  exposure  to  it.  In  the  case  of  operatives  in  lead- 
works,  emphasis  must  be  laid  upon  the  necessity  of  grinding  the 
pigments  under  water  to  prevent  the  fine  particles  escaping  as 
dust  into  the  air;  free  ventilation  is  requisite;  the  hands,  nails, 
and  beard  should  be  washed  and  brushed  carefully  before  eating, 
and  meals  should  not  be  taken  inside  the  factory.  A  weak  lem- 
onade of  sulphuric  acid  is  sometimes  used  as  a  beverage.  Its 
antidotal  power  may  be  reinforced  by  occasional  doses  of  mag- 
nesium sulphate. 

It  is  well  to  begin  treatment  with  some  magnesium  sulphate  as 
an  antidote  to  any  lead  present  in  the  alimentary  tract;  colic  will 
call  for  morphin  and  atropin  administered  hypodermically;  joint- 
pains  for  local  fomentations;  paralysis  for  electricity  and  massage. 
The  natural  process  of  elimination  of  lead  is  deliberate.  It 
escapes  slowly  by  the  urine,  and  five  to  ten  times  as  much  by 
the  bowels,  without  the  use  of  any  special  eliminant.  Several 
special  eliminants,  notably  potassium  iodid,  have  been  given  freely 
without  causing  any  increase  in  the  amount  of  lead  excreted. 


LEAD  327 

Careful  quantitative  tests  prove  that  a  slight  increase  attends  the 
use  of  hot  baths,  general  massage,  and  occasional  purgation. 
These  last,  combined  with  open-air  exercise  and  wholesome  diet, 
are  the  means  most  to  be  relied  on.  If  potassium  iodid  is  given, 
care  should  be  taken  that  it  does  not  increase  the  anemia.  A 
remission  should  be  allowed,  during  which  iron  preparations 
would  be  of  service. 

Postmortem  Appearances. — In  chronic  cases  the  pathologic 
changes  discovered  cannot  be  called  characteristic.  Where 
albuminuria  has  been  present,  the  kidneys  are  found  hard  and 
contracted,  the  seat  of  granular  degeneration.  When  colic  has 
been  a  conspicuous  symptom  a  portion  of  the  intestines  has  been 
found  constricted,  with  a  gray-black  discoloration  of  the  mucous 
lining.  When  there  has  been  local  paralysis  with  atrophy  the 
muscles  involved  have  been  found  wasted  and  fatty,  and  changes 
have  been  discovered  in  the  large  cells  in  the  anterior  cornua  of 
the  cord  and  in  the  peripheral  nerve-fibers.  The  blue  line  around 
the  gums  is  highly  significant. 

Distribution  in  the  Tissues. — In  examining  the  bodies  of 
2  cases  suddenly  fatal,  Blyth  separated  from  the  brain  of  one  an 
appreciable  amount  of  lead,  from  the  liver  an  amount  equivalent  to 
J  gr.  of  sulphate,  from  one  kidney  about  TV  gr.  In  a  dog  killed  by 
chronic  lead-poisoning,  in  parts  per  thousand,  the  bones  were 
found  to  contain  0.18  to  0.27;  the  kidneys,  0.17  to  0.20;  liver, 
o.io  to  0.33;  spinal  cord,  0.06  to  o.n;  brain,  0.04  to  0.05;  mus- 
cles, 0.02  to  0.04;  intestines,  o.oi  to  0.02,  and  traces  were  detected 
in  the  spleen,  blood,  and  bile. 

It  is  a  remarkable  fact  that  lead  is  frequently  found  in  the  cadav- 
ers of  persons  who  in  life  were  free  from  all  symptoms  of  lead- 
poisoning.  A  fallacious  conclusion  may  be  reached  if  the  con- 
tents of  the  stomach  should  contain  a  bit  of  melted  solder  from 
a  fruit  can  or  a  shot  derived  from  eating  game. 

In  the  absence  of  characteristic  symptoms  during  life,  if  the 
amount  of  lead  separated  from  the  tissues  should  be  small,  it 
should  not  be  regarded  as  significant  of  lead-poisoning. 

Lead  in  the  Urine. — From  a  case  which  had  symptoms  so 
vague  as  to  make  the  diagnosis  of  lead-poisoning  doubtful  there 
was  obtained  from  400  c.c.  (14  fl.  oz.)  of  urine  as  much  as  5.2  mg. 
(0.08  gr.)  of  metallic  lead.  Elimination  is  not  always  uniform. 
For  a  long  time  the  urine  is  free  from  lead  and  later  shows  it, 
without  further  administration  in  the  meantime. 

There  is  reason  to  believe  that  lead  is  not  an  uncommon  con- 
stituent of  the  urine.  Urine  analyses  for  lead  were  made  in  86 
cases,  in  the  healthy  and  the  sick,  with  the  result  of  finding  lead 
present  in  48  cases.  Most  of  them  were  chosen  because  of  their 


3*8 


THE    METALS 


exposure  to  lead  by  occupation  or  otherwise,  and,  so  far  as  these 
figures  are  a  guide,  in  not  more  than  50  per  cent,  of  the  community 
at  large  can  lead  be  detected  in  the  urine.  The  urines  of  persons 
known  to  be  in  perfect  health  were  almost  all  free  from  lead. 

Tests.— Hydrogen  Sulphid.— A  stream  of  this  gas  passed 
through  a  lead  solution,  neutral,  alkaline,  or  slightly  acid,  yields 
a  black  precipitate  of  lead  sulphid,  insoluble  in  the  alkaline  hy- 
droxids  or  the  moderately  dilute  acids.  If  the  amount  of  metal 
be  very  small,  the  precipitate  will  be  brown.  Hot  nitric  acid 
converts  it  into  soluble  lead  nitrate  and  free  sulphur  separates; 
by  continued  heat  the  acid  converts  the  sulphur  into  sulphuric 
acid,  and  this  precipitates  the  lead  as  lead  sulphate.  A  small 
amount  of  lead  would  remain  in  solution. 

Fallacies. — This  reagent  gives  a  like  precipitate  with  several 
other  metals,  such  as  copper  and  mercury.  To  distinguish  the 
lead  the  sulphid  may  be  dissolved  in  warm  dilute  nitric  acid, 
filtered,  the  filtrate  evaporated  to  dryness  to  expel  any  excess  of 
nitric  acid,  the  residue  taken  up  with  water,  and  the  clear  solu- 
tion tested,  as  stated  below,  with  potassium  iodid,  dilute  sulphuric 
acid,  or  potassium  chromate.  If  the  quantity  of  the  precipitate 
be  large,  it  can  be  reduced  to  metallic  lead  by  the  blowpipe  or 
charcoal. 

Delicacy. — From  a  solution  containing  25000  gr-  °f  lead  oxid 
to  10  gr.  of  water  this  test  gives  a  faint  brownish  tint  with  per- 
ceptible cloudiness. 

Potassium  Iodid. — This  reagent  gives,  with  very  small  amounts 
of  lead,  a  yellow  coloration;  with  larger  amounts,  a  yellow  pre- 
cipitate of  lead  iodid,  soluble  in  boiling  water,  from  which  it 
deposits,  on  cooling,  in  gold-colored  hexagonal  scales. 

Fallacies. — If  the  lead  be  small  in  amount  and  has  been  treated 
previously  with  nitric  acid,  a  brownish  color  will  be  caused  by  the 
iodin  freed  from  the  potassium,  unless  the  free  nitric  acid  has  been 
neutralized  or  driven  off  by  heat.  Lead  iodid  is  soluble  in  potas- 
sium hydroxid  and  in  strong  hydrochloric  acid. 

Delicacy. — A  very  small  quantity  of  the  reagent  will  cause  a 
satisfactory  deposit  of  small  plates  from  a  solution  of  YOOOO  gr. 

Sulphuric  Acid. — This  reagent,  diluted,  gives  a  white  crys- 
talline or  granular  precipitate  of  lead  sulphate,  which  is  favored 
by  the  addition  of  alcohol.  The  precipitate  is  soluble  in  hot  strong 
hydrochloric  acid,  in  ammonium  acetate,  and  in  a  large  excess  of 
potassium  hydroxid. 

Fallacies. — This  reagent  will  also  make  a  white  precipitate  with 
barium  and  strontium  salts,  and  with  fairly  strong  solutions  of 
calcium  compounds.  The  lead  sulphate  is  characterized,  how- 
ever, by  turning  black  with  ammonium  sulphid. 


LEAD  329 

Potassium  Chromate  or  Bichromate.— Either  of  these 
reagents  precipitates  lead  as  a  yellow  amorphous  deposit  soluble  in 
potassium  hydroxid  and  strong  hyrochloric  acid,  but  insoluble  in 
acetic  acid.  A  yellowish  precipitate  produced  by  potassium  chro- 
mate  in  neutral  copper  solutions  dissolves  in  acetic  acid  and  is 
thus  readily  distinguished  from  the  lead  precipitate. 

Detection  in  Gastric  Contents,  Tissues,  etc. — A  method 
suitable  for  the  urine,  feces,  gastric  contents,  or  the  finely  divided 
viscera  is  the  evaporation  of  the  fluid  or  the  dilution  of  the  solids 
to  the  consistence  of  a  gruel,  the  destruction  of  organic  matter  with 
potassium  chlorate  and  hydrochloric  acid  (see  p.  283),  and  filtra- 
tion while  hot.  While  some  of  the  lead  is  apt  to  remain  as  insol- 
uble sulphate  on  the  filter,  a  considerable  quantity  in  a  soluble 
combination  with  potassium  chlorid  passes  through.  In  toxico- 
logic  analysis,  as  a  rule,  the  total  amount  of  lead  is  not  in  excess 
of  what  will  be  dissolved.  The  filtrate  may  be  precipitated  with 
hydrogen  sulphid,  the  precipitate  dissolved  in  warm  dilute  nitric 
acid,  the  solution  filtered  and  evaporated  to  dryness,  the  residue 
redissolved  in  water,  and  tested  with  sulphuric  acid  or  potassium 
iodid. 

Detection  in  Urine. — The  following  method  for  the  urine  is 
very  delicate:  A  quart  of  urine  acidified  with  acetic  acid  is  evap- 
orated to  dryness  and  fused  in  a  crucible  with  a  little  pure  niter 
until  it  becomes  white.  When  the  crucible  is  cool,  dilute  hydro- 
chloric acid  is  added  hot  to  extract  the  residue  after  ignition. 
The  extract  is  then  filtered,  and  the  filtrate  treated  with  ammonium 
to  alkaline  reaction,  to  precipitate  the  phosphates  and  iron.  Am- 
monium sulphid  is  added  at  the  same  time  to  throw  down  the  lead 
and  iron  as  sulphids.  This  deposit  is  washed  three  times  by  decan- 
tation  with  hot  water;  then  water  acidified  with  hydrochloric  acid 
is  added,  and  the  whole  allowed  to  stand  until  the  next  day.  It 
is  then  filtered  through  a  small  filter  and  the  residue  washed.  A 
little  pure  nitric  acid  is  then  added,  drop  by  drop,  to  dissolve  the 
lead  sulphid  left  on  the  filter  and  carry  it  through  as  nitrate. 
This  filtrate  is  collected  in  a  watch-glass,  evaporated  to  dryness, 
and  the  final  test  made  by  adding  a  drop  of  water  and  a  crystal 
of  potassium  iodid.  A  yellow  precipitate  denotes  lead. 

Electrolysis. — To  electrolyze  the  filtrate  of  the  hot  decoction 
with  potassium  chlorate  and  hydrochloric  acid  it  is  placed  in  a 
glass  vessel  with  a  bottom  of  parchment-paper.  This  cell  is  im- 
mersed to  the  surface  level  in  an  outer  vessel  containing  distilled 
water  acidulated  with  sulphuric  acid.  In  the  inner  cell  is  placed 
the  cathode  of  four  Grove  cells  in  the  shape  of  platinum  foil 
50  cm.  square  (2  in.  by  4  in.).  Beneath  the  parchment  diaphragm, 
near  to  it  and  parallel  with  the  cathode  on  the  opposite  side,  is 


330  THE   METALS 

placed  the  anode.  In  six  hours  the  cathode  is  removed,  washed, 
dried,  and  cleaned  of  its  lead  with  warm  dilute  nitric  acid.  After 
driving  off  the  free  nitric  acid  by  heat  the  lead  is  precipitated  by 
dilute  sulphuric  acid  and  an  equal  volume  of  alcohol  added. 
After  being  set  aside  for  twenty  hours  the  precipitate  is  washed 
free  from  acid  with  water  containing  12  per  cent,  of  alcohol. 
Decanted,  ignited,  and  weighed,  100  parts  of  the  sulphate  equal 
68.319  parts  of  metallic  lead. 

Quantitative  Determination. — While  the  electrolytic  method 
is  preferable  when  the  amount  of  lead  is  small,  for  large  quantities 
it  is  better  to  precipitate  the  lead  dissolved  by  decoction  in  hot 
hydrochloric  acid  with  hydrogen  sulphid.  The  precipitate  may 
be  converted  into  sulphate  by  treating  it  first  with  warm  dilute 
nitric  acid,  filtrating,  evaporating,  dissolving  in  water,  and  pre- 
cipitating with  sulphuric  acid,  evaporating,  igniting,  and  weighing 
as  above,  calculating  68.319  parts  of  lead  for  100  of  the  sulphate. 


BISMUTH 

Symbol,  Bi.     Atomic  weight,  208.3. 

Occurrence. — The  metal  occurs  free  in  nature  and  also  as  a 
sulphid.  From  this  sulphid  it  is  obtained  by  first  roasting  until 
it  is  converted  to  oxid,  and  then  reducing  the  oxid  with  carbon. 

Properties. — Bismuth  is  a  reddish-white,  brittle,  crystalline 
metal.  Its  crystals  are  isomorphous  with  arsenic  and  antimony. 
It  is  unchanged  by  air  or  water,  and  is  a  good  conductor  of  elec- 
tricity. Its  ion  is  the  trivalent  bismuthion,  Bi"".  It  forms  some 
alloys  that  melt  below  the  boiling-point  of  water. 

Rose's  fusible  metal  consists  of  bismuth  2  parts,  lead  i,  and 
tin  i.  It  melts  at  93.8°  C.  (201°  F.). 

Wood's  metal  consists  of  bismuth  4  parts,  lead  2,  tin  i,  and 
cadmium  i.  It  melts  at  60.5°  C.  (141°  F.). 

Bismuth  sesquioxid,  Bi2O3,  is  a  yellow  powder  formed  by 
burning  bismuth  in  air.  It  is  also  formed  when  the  hydroxid, 
Bi(OH)3,  is  heated  and  loses  water.  Both  are  basic. 

Bismuth  hydroxid,  Bi(OH)3,  is  precipitated  from  bismuth 
solutions  by  excess  of  alkali.  It  is  an  insoluble  white  powder. 
With  nitric  acid  it  forms  bismuth  nitrate,  Bi(NO3)3,  showing  that 
it  is  a  triacid  base.  By  losing  the  constituents  of  water,  Bi(OH)3 
changes  to  bismuthyl  hydroxid,  BiO.OH,  which  is  a  monacid  base. 
In  reacting  with  nitric  acid  the  hydroxyl  is  replaced  and  bismuth 
oxynitrate  or  subnitrate,  BiO.NO3,  is  produced.  A  whole  series 
of  subsalts  or  basic  salts  are  formed  by  this  univalent  group, 
bismuthyl,  BiO. 

Bismuth  Subcarbonate  [(BiO)2CO3.H2O]  (Bismuthyl  Carbonate 


BISMUTH  331 

Oxy  carbonate}. — This  is  formed  when  a  solution  of  the  normal 
nitrate  is  treated  with  sodium  carbonate.  Carbon  dioxid  is 
given  off,  and  the  subcarbonate  is  precipitated  as  a  yellowish- 
white  insoluble  powder.  When  heated,  water  and  carbon  dioxid 
escape,  leaving  bismuth  oxid,  Bi2O3. 

Dose:   10  to  60  gr.  (0.666-4  gm.). 

Bismuth  Subnitrate  (BiO.NO3.H2O)  (Bismuthyl  Nitrate,  Oxy- 
nitrate). — When  bismuth  is  dissolved  in  nitric  acid  a  clear  solution 
of  the  normal  nitrate,  Bi(NO3)3,  is  obtained.  By  pouring  this 
solution  into  water  a  heavy  white  precipitate  of  bismuthyl  nitrate 
forms,  and  some  nitric  acid  is  left,  possibly  in  combination  with 
bismuth: 

Bi(N03)3     +     2H20     =     BiON03.H20      +     2HNO3. 

Dose:  10  to  60  gr.  (0.666-4  gm-)' 

Incompatibles. — Tannic  and  gallic  acids;  calomel;  sulphur; 
salicylic  acid;  potassium  iodid;  with  alkaline  bicarbonates  it 
causes  effervescence. 

Nylander's  reagent  is  an  alkaline  solution  of  bismuth  hydroxid 
by  means  of  sodium  potassium  tartrate  (p.  603).  When  boiled 
with  a  glucose  solution  the  reduced  metal  bismuth  is  precipitated 
gray  or  black. 

Bismuthi  et  ammonii  citras  (U.  S.  P.)  is  of  indefinite  com- 
position. The  ordinary  citrate  of  bismuth,  BiC6H5O7,  is  a  white 
insoluble  powder  which  in  ammonium  hydroxid  becomes  soluble. 
This  double  citrate  forms  small  pearly  scales  which  are  soluble 
in  water.  Dilute  acids  change  it  to  the  insoluble  form.  Dose: 

1  to  5  gr.  (0.066-0.33  gm.). 

Other  official  compounds  of  bismuth  are  Bismuthi  citras,  dose, 

2  gr.  (0.125  gm.);  bismuthi  subgallas,  dose  4  gr.  (0.250  gm.)  and 
bismuthi  subsalicylas,  dose  4  gr.  (0.250  gm.). 

Toxicology.— The  study  of  the  toxic  action  of  bismuth  is 
practically  that  of  the  salt  most  commonly  used  in  medicine,  the 
subnitrate.  This  white,  odorless,  almost  tasteless,  and  nearly 
insoluble  powder,  is  sometimes  used  as  a  cosmetic  under  the  name 
of  "  pearl  white."  It  is  much  esteemed  as  a  local  sedative  for 
gastric  and  intestinal  irritation  and  is  given  almost  ad  libitum. 
At  one  time  most  samples  were  imperfectly  freed  from  the  arsenic 
which  is  found  associated  with  bismuth  in  its  ores.  Antimony, 
lead,  and  a  trace  of  tellurium  have  been  found  in  it.  At  present, 
contaminants  are  rarely  detected,  owing  to  the  more  perfect 
methods  of  preparation  now  employed.  Owing  to  its  difficult 
solubility,  the  pure  subnitrate  in  any  but  very  large  doses  has  no 
toxic  action.  When  applied  to  open  wounds  and  extensive  burns 


332 


THE    METALS 


as  an  antiseptic,  some  absorption  is  apt  to  occur  with  symptoms 
of  systemic  poisoning. 

Symptoms. — While  the  salt  itself  has  only  a  feebly  acid  taste, 
yet  in  cases  of  poisoning  from  absorption  a  peculiar  metallic  taste 
is  complained  of,  accompanied  by  salivation,  foul  breath,  and  sore 
mouth.  There  are  vomiting,  abdominal  pain,  and  purging  of 
stools,  dark  from  bismuth  sulphid.  Sometimes  a  black  discolora- 
tion appears  upon  the  gums,  but  may  spread  over  the  whole  mouth. 
The  reaction  of  the  hydrogen  sulphid  generated  from  decom- 
posed food  with  bismuth  subnitrate  is  as  follows: 

2BiON03     +     3H2S     =     Bi2S3     +     2HNOS     +     2H2O. 

332 

The  black  Bi2S3  is  insoluble  in  ammonium  sulphid,  which  thus 
separates  it  from  the  sulphids  of  arsenic  and  antimony. 

The  strong  garlicky  odor  of  the  breath  sometimes  observed 
has  been  attributed  to  tellurium,  which  produces  this  effect, 
although  the  amount  is  very  minute.  As  the  gastro-enteric 
symptoms  are  similar  to  those  of  arsenic,  the  toxic  action  of  bis- 
muth was  at  one  time  ascribed  to  that  impurity.  Large  doses 
internally,  as  well  as  free  topical  applications  of  bismuth  salts, 
have  in  some  cases  caused  black  urinary  sediment,  albuminuria, 
and  tube-casts,  beside  the  usual  stomatitis,  loosened  teeth,  blue 
gingival  line,  diarrhea,  and  ulceration  of  the  intestines. 

Cases  have  been  described  which  show  peculiar  effects  on 
the  mouth  when  the  bismuth  salt  has  been  absorbed  at  distant 
points,  due  to  the  fact  that  bismuth  is  eliminated  largely  by  the 
saliva.  These  cases  are  remarkable  because  equally  large  amounts 
have  been  administered  by  the  mouth  without  injurious  con- 
sequences. In  one  case  an  extensive  burn  was  treated  with 
local  applications  of  bismuth  subnitrate,  proved  by  analysis  to  be 
pure.  In  two  weeks  there  was  a  severe  inflammation  of  the 
mouth  and  throat  with  adherent  black  exudations;  vomiting  and 
diarrhea  supervened  with  albuminuria.  Bismuth  was  detected 
in  the  urine  and  the  feces.  A  few  days  after  the  application  was 
discontinued  the  acute  symptoms  subsided. 

An  experimental  research  on  the  lower  animals,  using  a  pure 
salt  of  bismuth  hypodermically,  caused  death  after  symptoms 
like  those  just  described. 

Fatal  Dose. — The  earlier  reports  as  to  the  fatal  dose  must  be 
taken  with  much  allowance,  owing  to  the  fact  that  until  recent 
times  the  bismuth  salts  almost  always  contained  enough  arsenic 
to  cause  trouble  if  the  dose  was  a  liberal  one.  Death  has  fol- 
lowed a  dose  of  2  dr.  The  period  of  fatality  was  the  ninth  day. 
A  dose  three  times  as  large  has  been  recovered  from. 


SILVER  333 

Tests. — Hydrogen  sulphid  yields  a  black  precipitate  of  bis- 
muth sulphid.  If  this  is  dissolved  in  the  smallest  possible  quan- 
tity of  hot  nitrohydrochloric  acid  and  the  resulting  solution  poured 
into  an  excess  of  water,  a  copious  white  precipitate  of  bismuth 
oxychlorid  is  thrown  down. 

Extraction  from  the  tissues  is  done  by  boiling  the  finely 
divided  matter  for  two  hours  in  dilute  nitric  acid,  the  dissolved 
material  separated  by  filtration,  and  the  filtrate  evaporated  to 
dryness.  The  undissolved  organic  matter  is  destroyed  with 
strong  nitric  acid  and  then  boiled  with  dilute  nitric  acid,  filtered, 
and  dried. 

A  solution  of  both  residues  is  made  in  50  per  cent,  nitric  acid 
and  the  above  tests  are  applied. 


SILVER   (Argcntum) 

Symbol,  Ag.     Atomic  weight,  107.66. 

Occurrence. — Metallic  silver  is  sometimes  found  free  in  nature. 
Its  chief  ore  is  a  sulphid  which  also  contains  lead  sulphid.  Lead 
and  silver  are  extracted  together  and  roasted  in  air.  The  lead 
oxidizes  to  litharge,  but  silver  retains  its  metallic  character,  even 
at  a  high  heat,  like  the  other  noble  metals. 

Properties. — Silver  is  tenacious,  pure  white  in  color,  and 
maintains  the  highest  luster,  resisting  perfectly  the  action  of  oxy- 
gen and  water  vapor.  By  air  containing  a  trace  of  hydrogen 
sulphid  and  by  other  sulphids  and  organic-sulphur  compounds, 
silver  is  blackened  with  a  film  of  sulphid.  It  has  a  specific  gravity 
of  10.5,  is  the  best  conductor  of  electricity  and  heat,  and  melts  at 
1000°  C.  (1832°  F.).  When  the  metal  is  precipitated  in  the 
metallic  state  by  reduction  from  the  solutions  of  its  salts,  it  is 
not  white,  like  the  normal  form,  but  may  be  yellow,  brown,  gray, 
or  black.  When  reduced  from  alkaline  solutions  it  assumes 
a  suspended  condition  of  a  red  or  brown  color;  and  when  dry 
takes  on  a  metallic  luster  and  any  one  of  several  colors — yellow, 
green,  red,  or  violet.  These  are  considered  to  be  allotropic 
forms. 

Colloidal  Silver. — In  the  presence  of  organic  compounds  like 
gelatin,  casein,  citric  acid,  etc.,  reducing  agents  act  without  pre- 
cipitation. The  result  is  an  olive-brown,  stable  solution  which 
should  not  be  exposed  to  light  or  air.  This  colloidal  silver  differs 
from  metallic  silver  in  being  apparently  soluble  in  water,  yet  it 
dissociates  very  little  argention  for  the  reaction  with  chloridion. 
Though  it  is  bactericidal  and  used  as  a  surgical  antiseptic,  it  does 
not  permeate  membranes.  The  only  difference  between  this 
colloidal  solution  and  a  true  suspension  is  that  of  size  of  the  sus- 


334  THE    METALS 

pended  particles.  Those  of  the  colloidal  solution  are  so  small  that 
by  collisions  with  each  other  they  keep  suspended  and  overcome  the 
gravitation  tendency.  The  ultramicroscope,  by  intense  oblique 
illumination,  makes  the  particles  visible  like  those  of  dust  floating 
in  the  air  when  illuminated  by  a  sunbeam. 

By  its  luster  and  rarity  silver  commends  itself  for  precious 
coins,  but  because  of  its  softness  it  is  not  fit  for  any  rough  use 
until  alloyed  with  about  10  per  cent,  of  copper,  which  makes  it 
harder.  From  coins  pure  silver  is  obtained  by  first  dissolving  in 
nitric  acid,  which  takes  up  both  silver  and  copper  and  precip- 
itates the  silver  with  sodium  chlorid,  leaving  the  copper  nitrate  in 
solution.  Silver  chlorid,  dried  and  heated  in  a,  crucible  with 
sodium  carbonate,  yields  the  silver  as  a  metallic  button,  the  chlorin 
going  to  the  sodium  to  form  sodium  chlorid  and  carbon  dioxid 
escaping  as  vapor. 

Silver  is  not  affected  by  the  strongest  alkalis,  nor  by  any  dilute 
acid  except  nitric.  It  is  soluble  in  nitric  and  sulphuric  acids  and 
solutions  of  potassium  cyanid. 

The  Ion  of  Silver. — Argention,  Ag*,  is  univalent  and  colorless. 
Its  hydroxid  is  strongly  basic,  like  the  alkalis,  forming  soluble 
salts  that  are  neutral.  The  ion  passes  into  the  metallic  state  with 
great  readiness.  Its  salts  in  contact  with  organic  matter,  stimu- 
lated by  sunlight,  separate  the  finely  divided  metal  of  a  brown  or 
black  color.  Metallic  silver  is  not  poisonous,  as  is  often  demon- 
strated by  the  use  of  silver  wire  in  closing  wounds  by  suture,  and 
the  absence  of  injurious  consequences  when  silver  coins  have  been 
swallowed  accidentally.  But  argention  is  an  active  poison.  It 
is,  however,  a  reagent  for  precipitating  halogens,  and,  owing  to 
the  wide  distribution  of  the  chloridion  of  common  salt  in  the 
tissues,  the  argention  is  quickly  thrown  out  of  action  and  then 
reduced  to  the  metallic  state  as  a  permanent  deposit. 

Silver  Oxid  (Ag2O)  (Argenti  Oxidum).—  There  are  three  oxids 
of  silver:  Ag4O,  AgO,  and  Ag2O.  The  last  is  called  normal,  and 
is  the  only  one  of  medical  interest.  At  ordinary  temperature  the 
alkaline  hydroxids  precipitate  from  solution  of  silver  nitrate  this 
normal  silver  oxid,  Ag2O.  It  is  a  brown  powder  of  slight  solu- 
bility, but  sufficient  to  give  an  alkaline  reaction.  Dose:  J  to  \  gr. 
(0.011-0.016  gm.),  best  mixed  with  chalk  and  given  in  capsules. 
It  is  incompatible  with  ammonia,  phosphorus,  organic  matter,  and 
the  salts  of  mercury,  iron,  bismuth,  and  copper. 

Silver  Chlorid  (AgCl)  (Argenti  Chloridum).—Thh  is  the  white 
precipitate  formed  when  the  ions  of  silver  and  chlorin  meet. 
A  white  powder,  it  turns  gray  and  violet  on  exposure  to  light, 
the  darkening  being  due  to  change  of  AgCl  to  the  subchlorid, 
Ag2Cl,  and  free  chlorin;  it  is  in  proportion  to  the  intensity  of  the 


SILVER  335 

light.  While  very  sparingly  soluble  in  water  silver  chlorid  dissolves 
in  ammonia,  the  thiosulphates,  and  potassium  cyanid. 

Silver  bromid,  AgBr,  is  obtained  as  a  fine  yellowish  precipi- 
tate when  argention  and  bromidion  are  brought  together.  It 
resembles  silver  chlorid,  but  is  much  less  soluble  in  ammonia, 
though  soluble  in  thiosulphates.  It  is  more  sensitive  to  light 
than  the  chlorid. 

Bromid-gelatin  plates  for  photography  are  prepared  by  adding 
ammonium  bromid  to  solution  of  gelatin,  and  in  the  dark  adding 
silver  nitrate.  Silver  bromid  is  precipitated  in  a  finely  divided 
state,  embedded  in  the  gelatin: 

AgNO3     +     NH4Br     =     NH4NO3     +     AgBr. 

By  washing  the  cooled  mass  the  excess  of  ammonium  bromid 
and  the  ammonium  nitrate  are  removed.  When  warmed,  the 
sensitive  gelatin  melts  and  is  applied  as  a  thin  film  to  glass  or 
celluloid.  Such  a  plate  in  the  focus  of  a  camera  has  its  silver 
bromid  reduced  to  sub-bromid  in  proportion  to  the  light  coming 
from  the  object. 

Developers. — The  process  of  reduction  is  completed  by  im- 
mersing the  plate  in  a  reducing  liquid  called  a  developer.  The 
developer  is  a  solution  of  ferrous  sulphate,  pyrogallic  acid,  potas- 
sium ferro-oxalate,  etc.  Metallic  silver  is  deposited  in  proportion 
to  the  intensity  of  the  light  that  made  the  initial  reduction.  The 
lights  of  the  picture  have  caused  a  dense  precipitate,  the  shadows 
little  or  none.  At  a  satisfactory  point  in  development  the  plate 
is  washed  free  of  silver  bromid  by  sodium  thiosulphate,  or  hypo, 
and  there  remains  a  fixed  negative — that  is,  a  picture  which  re- 
verses the  lights  and  shadows. 

Silver  Nitrate  (AgNO3)  (Argenti  Nitras,  Lunar  Caustic).— 
Concentrated  nitric  acid  dissolves  pure  silver,  and  on  evaporation 
leaves  colorless  crystalline  plates.  These  are  readily  soluble, 
have  a  metallic  taste,  and  are  stable  apart  from  organic  matter, 
but  with  it  they  blacken  by  reduction  to  metallic  silver.  It  forms 
insoluble  compounds  with  albumin,  and  hence  is  a  superficial 
caustic,  producing  a  shallow  eschar,  which  soon  blackens.  This 
quality  makes  it  useful  as  a  hair  dye  and  an  indelible  ink.  To 
obviate  brittleness  the  crystals  are  melted  with  4  per  cent,  hydro- 
chloric acid  and  cast  in  sticks  called  argenti  ultras  fusus.  For 
mild  local  use  stick  caustic  is  sometimes  diluted  with  potassium 
nitrate,  making  mitigated  nitrate,  argenti  ultras  mitigatus}  U.  S.  P. 
The  incompatibles  are  alkalis,  alcohol,  chlorids,  acetates,  bromids, 
iodids,  carbonates,  cyanids,  arsenites,  salts  of  antimony,  copper 
and  manganese,  vegetable  extracts,  phosphates,  sulphids,  tannic 
acid,  and  vegetable  astringents. 


336  THE    METALS 

Silver  cyanid,  U.  S.  P.,  (AgCN),  is  precipitated  as  a  white 
solid  when  argention  meets  cyanidion  (CN)': 

Ag%  (NO,)'     +     K-,  (CN)'     =      K-,  (N08)'     +     AgCN. 

By  adding  excess  of  potassium  cyanid  a  soluble  double  salt 
is  formed: 

AgCN       +        K-,  (CN)'       =       K-,  [Ag(CN)2]'. 

This  solution  fails  to  give  the  ordinary  silver  reactions  because 
it  has  no  argention,  the  metal  being  locked  up  in  the  silver  cyanidion 
[Ag  (CN)2]/.  In  electroplating  with  this  solution  the  double  salt 
breaks  down  and  the  silver  goes  to  the  object  at  the  negative  pole 
to  be  deposited  as  a  uniform  metallic  coating. 

Toxicology. — Of  7  cases  reported  due  to  accidental  swallowing 
of  the  caustic  when  applied  to  the  throat  for  local  affections,  5 
were  in  children  (i  of  these  was  fatal)  and  2  in  adults. 

Symptoms. — The  contact  of  the  caustic  causes  instant  pain  in 
the  throat  and  stomach,  prompt  emesis,  and  later  purging  of 
bloody  matters.  After  absorption  takes  place,  nervous  symptoms 
supervene,  such  as  vertigo,  spasms,  disturbed  respiration,  and 
coma. 

Chronic  Poisoning. — Repeated  cauterization  with  silver  nitrate 
caused  the  following  effects:  Emaciation,  followed  in  a  few  weeks 
by  paralysis  and  other  nervous  affections,  with  ecchymoses  under 
the  eyelids.  The  face  turned  a  leaden  color,  the  sclerotics  were 
discolored,  many  brown-black  spots  appeared  all  over  the  body, 
and  a  blue  line  was  seen  on  the  gums.  Similar  discoloration 
patches,  oval  and  about  the  size  of  apple  seeds,  have  been  found 
in  silver  workers,  and  are  attributable  to  absorption  through 
abrasion  of  the  hands.  The  patches  proved  to  be  due  to  deposit 
of  metallic  silver  in  the  tissues. 

A  leaden-bluish  discoloration  of  the  face  and  possibly  of  other 
parts  of  the  body  is  sometimes  brought  on  by  the  medicinal  use 
of  small  doses  of  silver  nitrate  given  for  a  long  period.  No  man- 
ner of  treatment  is  of  any  avail  to  remove  this  discoloration. 

Fatal  Dose. — Death  has  resulted  from  30  gr.  taken  by  an  adult. 

Fatal  Period. — In  six  hours  after  swallowing  a  piece  of  "  lunar 
caustic"  a  child  of  fifteen  months  died  in  convulsions. 

Treatment. — Large  drafts  of  common  salt  and  water  will  favor 
vomiting  and  at  the  same  time  be  the  best  antidote,  forming  insol- 
uble silver  chlorid.  The  stomach-pump  may  be  used,  if  necessary. 
This  treatment  can  be  followed  up  with  a  diet  of  eggs  and  milk. 

Postmortem  Appearances. — The  local  action  of  the  caustic 
will  be  seen  in  stains,  at  first  white,  and  on  exposure  to  light, 


IRON  337 

turning  black.  These  stains  are  found  on  the  lips,  in  the  mouth, 
on  white  clothing,  and  on  the  mucous  membrane  of  the  digestive 
tract  touched  by  the  poison.  Gastro-intestinal  inflammation  is 
present. 

Tests. — Hydrochloric  acid  and  soluble  chlorids  precipitate 
from  soluble  salts  of  silver,  white-silver  chlorid,  insoluble  in  nitric 
acid,  but  readily  soluble  in  ammonia-water  and  in  potassium 
-cyanid. 

Hydrogen  sulphid  or  ammonium  sulphid  precipitates  a  dark 
brown  silver  sulphid  in  accordance  with  this  equation: 

2AgN03       +       H2S  Ag2S       +        2HN03. 

Potassium  iodid  gives  a  yellow  precipitate,  and  potassium 
•chromate  a  blood-red  precipitate. 

Extraction  from  Stomach  Contents. — Finely  divided  tissues 
•or  gastric  contents  are  digested  with  ammonia  and  potassium 
cyanid.  The  decanted  fluid  is  treated  with  excess  of  hydrochloric 
acid  and  the  insoluble  chlorid  separated  by  decantation;  the  pre- 
cipitate is  washed  on  a  filter  with  hot  water,  dried,  and  reduced  on 
-charcoal  to  metallic  silver. 


VI.— THE  IRON  GROUP 

THIS  group  includes  iron,  cobalt,  nickel,  manganese,  zinc,  and 
•chromium,  heavy  metals  whose  sulphids  are  insoluble  in  water, 
but  are  soluble  in  dilute  acids. 

IRON    (Ferrum) 

Symbol,  Fe.     Atomic  weight,  56. 

Iron  is  the  most  important  of  the  metals,  because  of  the  abun- 
dance of  its  ores,  the  ease  of  its  extraction,  and  the  value  of  its 
properties. 

Occurrence. — Iron  ranks  next  to  aluminium  in  abundance  in 
the  crust  of  the  earth.  Rarely  it  occurs  free  in  nature  in  two 
forms,  meteoric  and  telluric.  The  metal  of  fallen  meteorites  is 
never  pure,  as  it  contains  cobalt,  nickel,  and  other  metals.  The 
telluric  kind  is  found  in  small  quantities  in  lavas  and  basalt. 
Its  most  common  ores  are  oxids,  such  as  magnetic  oxid,  Fe3O4; 
red  hematite,  Fe2O3;  carbonate,  FeCO3;  and  sulphids  or  iron 
pyrites,  FeS2;  magnetic  pyrites,  FeS4;  copper  pyrites,  CuFeS2. 

Nearly  all  rocks  contain  silicate  of  iron,  which,  decomposing  to 


338  THE    METALS 

oxid,  imparts  a  red  color  to  the  soil.  Plants  absorb  the  iron  and 
store  it  in  the  green  chlorophyl  of  leaves,  which  is  essential  to 
the  interaction  of  carbon  oxid,  water,  and  oxygen,  by  which  the 
tissues  are  built  up.  Having  served  the  respiratory  function  of 
the  plant,  iron  is  assimilated  by  animals  from  their  vegetable  food, 
stored  in  the  liver  as  a  loose  compound  called  /erratin,  from  which 
it  is  taken  as  required  to  become  a  necessary  constituent  of  the 
hemoglobin  which  carries  the  oxygen  of  respiration  to  the  animal 
tissues.  It  is  eliminated  from  the  body  as  a  constituent  of  bile 
coloring-matter.  In  animals  and  plants  its  physiologic  impor- 
tance appears  to  be  due  to  a  catalytic  influence  exerted,  by  which 
it  accelerates  the  oxidation  processes. 

In  extracting  the  metal  from  its  carbonate,  sulphid,  and  hy- 
droxid  the  ore  is  roasted  in  air,  evolving  from  sulphids,  SO2; 
carbonates,  CO2;  hydroxids,  steam;  all  of  these  escaping  as  gases. 
From  the  oxid  simple  reduction  with  carbon  suffices: 

Fe3O4        +       4C       =       4CO        +       3Fe. 

Limestone  or  sand  and  feldspar  are  also  heated  with  the  ores 
in  order  to  take  up  impurities  and  protect  the  metal  when  it  is 
freed.  As  molten  metal  it  is  received  in  molds  in  sand.  This 
crude  pig  iron  always  contains  some  carbon,  silicon,  sulphur, 
phosphorus,  and  other  impurities.  Cast  iron  contains  about  5 
per  cent,  of  carbon.  It  melts  at  a  lower  temperature  than  pure 
iron,  is  not  so  hard  as  steel,  and  is  more  brittle  than  wrought 
iron.  By  melting  again  and  blowing  in  air  some  of  the  carbon, 
phosphorus,  sulphur,  etc.,  is  burned  out  and  a  purer  product 
obtained  called'  wrought  iron.  This  is  tough,  strong,  malleable, 
and  ductile,  and  contains  less  than  0.5  per  cent,  of  carbon.  It 
welds  easily,  but  is  soft  and  bends  under  strain.  When  cast  iron 
is  melted  and  purified  by  oxidation  and  then,  by  the  addition  of 
iron  containing  carbon,  converted  into  a  product  containing 
between  0.8  and  2  per  cent,  carbon,  we  have  steel.  When  steel  is 
heated  and  suddenly  cooled  it  becomes  extremely  hard  and  brittle. 
If  carefully  heated  and  then  cooled  slowly,  it  becomes  soft  and 
elastic.  In  its  soft  state  steel  can  be  given  the  shape  desired  and 
by  tempering  at  different  temperatures  the  hardness  can  be  regu- 
lated to  the  degree  required  for  the  uses  of  the  instrument. 

Properties. — Pure  iron  is  silver  white  and  susceptible  of  a 
high  polish.  It  is  more  malleable,  softer,  and  less  tenacious  than 
wrought  iron.  Its  specific  gravity  is  7.84.  It  melts  only  at  the 
highest  temperatures,  but  at  a  lower  point — about  600°  C.  (1112° 
F.) — it  becomes  plastic  like  wax,  and  can  be  pressed,  rolled,  forged, 
and  welded.  In  dry  air  it  is  unchanged  at  ordinary  temperatures, 


IRON  339 

but  at  a  red  heat  it  oxidizes.  In  moist  air  it  forms  a  rust  of 
hydrate  and  oxid.  Galvanized  iron  is  made  so  by  dipping  the  iron 
into  molten  zinc  to  protect  it  from  moisture.  The  purest  com- 
mercial form  is  card  teeth  or  piano  wire. 

Reduced  iron  (Ferrum  reductum,  Quevenne's  iron,  iron  by 
hydrogen)  is  prepared  by  heating  the  oxid,  Fe3O4,  in  a  current  of 
hydrogen.  The  hydrogen  abstracts  oxygen  to  form  water,  leaving 
a  gray-black  powder,  odorless,  tasteless,  and  insoluble.  Dose: 
i  to  5  gr.  (0.066-0.333  gm.).  Incompatible  with  potassium  chlo- 
rate and  permanganate;  hydrogen  dioxid;  salts  of  antimony,  cop- 
per, bismuth,  lead,  mercury,  and  silver. 

Iron  dissolves  in  hydrochloric  acid,  forming  a  chlorid,  and  in 
dilute  sulphuric  acid,  forming  a  sulphate,  in  each  case  liberating 
hydrogen.  The  electric  charge  of  the  hydrion  has  changed  the 
iron  to  ferrion.  It  unites  directly  with  the  halogens,  sulphur, 
phosphorus,  arsenic,  and  antimony.  When  dipped  into  concen- 
trated nitric  acid  it  becomes  passive.  Some  electric  condition  is 
induced  which  protects  it  from  further  action  by  either  dilute  or 
strong  nitric  acid. 

Ferrous  and  Ferric  Ions. — There  are  two  kinds  of  elementary 
ions  formed  by  iron,  one  divalent,  dijerrion,  the  other  trivalent, 
trijerrion.  The  compounds  of  the  former  are  similar  to  those  of 
magnesium  and  are  called  ferrous;  those  of  the  latter  resemble 
aluminium  salts  and  are  called  ferric.  Diferrion  has  an  inky 
taste  and  is  colorless,  but  in  aqueous  solution  forms  greenish  fer- 
rous hydroxid.  It  has  a  tendency  to  pass  into  triferrion,  also 
colorless,  but  in  water  forming  brown  ferric  hydroxid.  This 
brown  hydroxid  is  in  colloidal  solution,  having  been  split  off 
from  the  ferric  salt  by  hydrolytic  dissociation.  When  diferrion, 
Fe",  changes  to  triferrion,  Fe"%  by  the  action  of  oxidizing  agents 
it  receives  an  additional  ionic  charge  which,  under  favorable  con- 
ditions, it  surrenders  to  reducing  agents,  passing  back  to  the 
divalent  form,  Fe".  The  effect  of  exposure  of  a  ferrous  solution 
to  the  air  is  to  cause  oxygen  and  water  to  form  hydroxidion,  the 
negative  ion  needed  to  give  to  diferrion  its  increased  positive 
charge.  The  change  takes  place  in  the  sense  of  the  following 
equations: 

3FeCl2     +     O     +     H2O  2FeCl3     +     Fe(HO)2 

Ferrous  chlorid.  Ferric  chlorid.          Ferrous  hydroxid. 

The  ferrous  hydroxid  with  the  co-operation  of  water  takes  more 
oxygen  and  forms  the  ferric  hydroxid: 

,2Fe(HO)2      +      O      +      H20  2Fe(HO)3 

Ferrous  hydroxid.  Ferric  hydroxid. 


340  THE    METALS 

Ferrous  Chlorid  (FeCl2)  (Iron  Protochlorid).—When  iron  is 
heated  in  a  current  of  dry  hydrochloric-acid  gas  a  white  salt  is 
obtained.  This  anhydrous  compound  takes  up  4  parts  of  water 
of  crystallization,  turning  green  in  color.  When  excess  of  iron 
is  dissolved  in  hydrochloric  acid  a  pale  green  solution  of  the 
ferrous  chlorid  is  formed.  The  dissociation  of  ferrous  chlorid  in 
solution  is  represented  thus:  Fe",  Cl',  Cl'.  When  chlorin  is 
passed  into  the  solution  the  cation  Fe"  takes  a  third  ionic  charge, 
the  chlorin  neutral  atom  changing  to  the  anion  chloridion: 

Fe"Cl',  Cl',       +       Cl  Fe"*Cl',  Cl',  Cl'. 

This  is  an  illustration  of  the  fourth  mode  of  ion  formation;  where 
an  atom  changes  to  an  ion,  at  the  same  time  giving  an  additional 
charge  of  electricity  to  an  ion  already  present.  It  is  called  oxida- 
tion in  the  sense  that  it  increases  the  electric  charges  of  an  ion; 
whereas  reduction  diminishes  the  charges.  When  the  above 
equation  is  reversed  it  represents  reduction. 

Ferric  Chlorid  (FeCl3,6H2O)  (Ferri  Chloridiim,  Sesquichlorid, 
or  Perchlorid). — The  pharmaceutic  product  is  prepared  by  adding 
to  a  solution  of  ferrous  chlorid  nitric  and  hydrochloric  acids  with 
heat.  Fumes  of  nitrogen  dioxid  are  formed: 

FeCl2     +     HNO3     +     HC1     =     FeCl3     +     H2O     +     NO2. 

On  evaporation  the  ferric  chlorid  is  obtained  as  an  orange-yellow 
deliquescent  mass  of  acid  reaction  and  strongly  styptic  taste. 

The  pure  anhydrous  ferric  chlorid  is  obtained  as  a  sublimate 
of  dark  green  crystals  when  iron  is  heated  in  a  current  of  chlorin. 
They  dissolve  in  water  with  a  rise  of  temperature  yielding  a  yellow- 
brown  solution  from  which  the  anhydrous  salt  cannot  be  again 
obtained.  By  evaporation  yellow  hydrates  crystallize  which  by 
heat  decompose  to  HC1  and  Fe(HO)3. 

In  the  presence  of  substances  which  oxidize  readily,  such  as 
morphin,  ferric  chlorid  decomposes  water,  sets  free  available 
oxygen,  and  is  itself  reduced  to  ferrous  chlorid  thus: 

2FeCl3     +      H20      =      2FeCl2     +      2HC1     +      O. 

Liquor  ferri  chloridi  is  an  aqueous  solution  of  ferric  chlorid 
containing  37.8  per  cent,  of  anhydrous  salt  with  some  free  hydro- 
chloric acid.  It  is  a  reddish-brown,  acid,  astringent  liquid  of  a 
specific  gravity  of  1.405. 

Tinctura  ferri  chloridi  (muriated  tincture  oj  iron)  is  prepared 
by  mixing  the  above  solution  with  3  volumes  of  alcohol  and  keeping 


IRON  341 

in  a  stoppered  bottle  for  three  months.  From  the  alcohol  certain 
ethereal  compounds  are  produced  which  impart  to  the  acid  brown- 
ish liquid  their  odor,  taste,  and  medicinal  effect.  It  contains 
13.28  per  cent,  of  FeCl3.  This  is  a  valuable  ferruginous  tonic, 
which  should  be  taken  freely  diluted  in  water,  syrup,  or  glycerin, 
and  through  a  tube  to  prevent  action  on  the  teeth.  Dose:  5  to 
20  tit  (0.33-1.33  c.c.).  Its  incompatibles  are  mucilage  of  acacia, 
astringent  infusions  and  tinctures,  tannic  acid,  antipyrin,  and 
alkalis  and  their  carbonates. 

Ferric  Hydroxid  (Ferric  Hydrate,  Ferri  Oxidum  Hydratum}.— 
When  alkaline  bases  are  added  to  solutions  of  ferric  salts,  a  brown, 
flocculent,  gelatinous  precipitate  of  ferric  hydroxid  is  obtained: 

FeCl3        +        3NaHO  Fe(HO)3        +        aNaCl. 

The  fresh  hydroxid  is  soluble  in  acids  and  in  solution  of  ferric 
chlorid.  On  standing  it  assumes  less  soluble  forms,  growing  denser 
and  to  some  extent  giving  up  the  constituents  of  water,  thus: 

2Fe(HO)3  Fe203  +  3H2O. 

When  freshly  precipitated  and  strained  off  in  a  state  of  loose 
magma  it  is  an  efficient  antidote  to  arsenic,  but  the  anhydrid 
change  that  occurs  in  time  lessens  materially  its  virtue  in  this 
respect: 

Fe(HO)3       +       H3AsO3  FeAsO3       +       3H2O. 

Arsenous  acid.  Ferric  arsenite. 

Ferri  Hydroxidum  cum  Magnesii  Oxido  (U.  S.  P.).— This 
is  made  by  mixing,  when  required,  an  excess  of  calcined  magnesia 
with  solution  of  ferric  sulphate: 

Fe2(S04)3   +   3MgO   +   3H20   ==    2Fe(HO)3   +   3MgSO4. 

The  whole  mixture  of  ferric  hydroxid,  magnesium  sulphate,  and 
some  excess  of  magnesium  oxid  is  of  service  and  may  be  given 
immediately  without  straining. 

Dialyzed  Iron  (Ferrum  Oxy  datum  Dialysatum). — This  is  a  5- 
per  cent,  solution  of  colloidal  ferric  hydroxid  once  used  in  medicine. 
It  is  prepared  by  adding  ammonium  hydroxid  to  a  concentrated 
solution  of  ferric  chlorid.  The  ferric  hydroxid  first  formed  dis- 
solves in  the  ferric  chlorid  when  shaken.  This  saturated  solution 
of  basic  oxychlorid  of  iron  is  put  in  a  dialyzer  having  a  partition 
of  parchment-paper,  and  floated  on  water.  The  ammonium 
chlorid  quickly  diffuses  into  the  water,  which  is  frequently  re- 
newed, until  there  is  no  reaction  with  silver  nitrate.  There  is 
hydrolytic  dissociation  of  part  of  the  ferric  oxychlorid  into  hydro- 


342  THE    METALS 

chloric  acid  which,  when  split  off,  passes  out  through  the  mem- 
brane, and  colloidal  ferric  hydroxid  which  remains  in  the  dialyzer 
with  some  trace  of  chlorid.  In  the  dialyzer  is  left  a  dark  red 
colloidal  solution  (the  dialysate),  the  constituents  of  which  are  not 
dissociated,  having  in  that  state  none  of  the  properties  of  the  ferric 
ion.  It  instantly  separates  the  insoluble  gelatinous  hydroxid  on 
the  addition  of  an  electrolyte,  such  as  alkalis,  neutral  salts,  and 
sulphuric  acid  (p.  93). 

Ferrous  lodid  (FeI2). — Elementary  iodin  in  excess  and 
metallic  iron  as  card  teeth  unite  directly  in  the  presence  of  warm 
water,  forming  a  pale  green  solution.  On  evaporation  greenish 
crystals  of  ferrous  iodid  separate.  In  air  the  iodid  readily  decom- 
poses, forming  ferric  oxid,  but  if  protected  by  sugar  the  oxidation 
is  prevented.  In  the  following  preparations  sugar  is  introduced 
for  the  purpose  of  keeping  the  ferrous  salt  from  changing  to  ferric 
compounds  which  have  more  astringency  and  irritating  quality: 

Pilulse  ferri  iodidi  (Blancard's  pills)  not  only  have  sugar  in  the 
pill-mass,  but  are  further  protected  by  a  coating  of  balsam  of 
tolu. 

Syrupus  ferri  iodidi  is  a  syrupy  solution  of  5-per  cent,  ferrous 
iodid,  transparent,  greenish,  and  neutral.  Dose:  5  to  50  TTL  (0.33- 

2   C.C.). 

Ferrous  Sulphid  (FeS).— When  iron  filings  and  flowers  of 
sulphur  are  heated  together  a  black  brittle  mass  is  formed  of  the 
composition,  FeS.  Its  chief  use  is  in  the  preparation  of  hydrogen 
sulphid.  As  it  is  readily  decomposed  by  acids,  it  is  not  precipi- 
tated when  hydrogen  sulphid  is  passed  into  ferrous  solutions. 
The  proper  precipitant  for  the  iron  group  is  ammonium  sulphid, 
which  yields  black  hydrated  iron  sulphid.  Ferrous  sulphid  in 
the  air  oxidizes  to  ferrous  sulphate: 

FeS  +  40  FeS04. 

Ferrous  Sulphate  (FeSO4.yH2O)  (Ferri  Sulphas,  Copperas, 
Green  Vitriol). — The  term  vitriol  is  applied  to  metallic  sulphates 
of  divalent  ions;  thus,  copper  sulphate  is  blue  vitriol  and  zinc 
sulphate  is  white  vitriol.  Ferrous  sulphate  can  be  obtained 
by  the  action  of  dilute  sulphuric  acid  on  iron.  The  solution 
evaporated  yields  large  pale  green  prismatic  crystals,  having 
a  styptic  taste  and  acid  reaction.  In  the  air  it  effloresces,  absorbs 
oxygen,  and  partially  changes  to  brown  ferric  sulphate.  It  is 
incompatible  with  vegetable  astringents,  tannic  acid,  alkalis,  borax, 
lime-water,  carbonates,  ammonium  and  calcium  chlorid,  lead 
acetate,  potassium  iodid,  and  nitrate. 

Ferri  Sulphas  Exsiccatus  (FeSO4 .  H2O).— Dried  sulphate  is 
prepared  by  heating  ferrous  sulphate  at  100°  C.  (212°  F.)  until 


IRON  343 

it  ceases  to  lose  weight.  It  is  a  grayish  white  powder,  useful  in 
making  pills.  Dose:  £  to  2  gr.  (0.033-0.133  gin.). 

Ferri  sulphas  praecipitatus,  granulated,  is  ferrous  sulphate 
separated  as  a  crystalline  powder  from  solution  in  weak  sulphuric 
acid  by  mixing  with  alcohol.  It  is  a  convenient  form  for  dis- 
pensing. 

Liquor  ferri  tersulphatis  is  a  36-per  cent,  solution  of  normal 
ferric  sulphate,  Fe2(SO4)3,  and  is  made  by  heating  a  solution 
of  ferrous  sulphate  with  sulphuric  and  nitric  acids.  The  nitric 
acid  oxidizes  diferrion  to  triferrion.  On  evaporating  and  heating 
the  residue  a  yellowish  white  powder  is  obtained.  Placed  in  water, 
it  at  first  does  not  dissolve,  but  after  some  time  it  forms  a  strong 
brown-red  solution.  Because  of  this  slow  solubility  the  salt  is 
usually  kept  in  the  official  solution  ready  made. 

Monsel's  salt  is  a  basic,  or  oxy-,  sulphate  used  in  surgery  as  a 
local  hemostatic.  It  is  a  yellowish  powder  obtained  by  evapora- 
tion from  MonsePs  solution,  which  is  the  official  liquor  jerri  sub- 
sulphatis,  containing  43.7  per  cent,  of  the  salts.  This  solution  is 
prepared  like  that  of  the  normal  sulphate,  but  with  less  sulphuric 
acid.  It  is  supposed  to  contain  ferric  hydroxid,  Fe(HO)3,  joined 
to  ferric  sulphate,  Fe2(SO4)3.  It  is  a  dark,  reddish  brown,  highly 
astringent,  almost  syrupy  solution,  causing  but  little  local  irri- 
tation. 

Ferric  Nitrate  (Fe(NO3)3).— By  dissolving  ferric  hydroxid  in 
nitric  acid  a  solution  of  this  salt  results,  which  when  6  per  cent, 
strong  is  called  liquor  ferri  nitratis.  It  is  transparent,  amber 
colored,  acid,  and  styptic.  Dose:  5  to  15  tT],  well  diluted  (0.33- 

1  gm.). 

Ferrous  carbonate,  FeCO3,  occurs  in  nature  as  "bog  ore." 
Insoluble  in  pure  water,  it  dissolves  in  natural  carbonated  waters 
by  changing  to  a  soluble  ferrous  bicarbonate,  FeH2(CO3)2.  It  is 
formed  when  alkaline  carbonates  act  on  ferrous  salts: 

FeSO4     +     Na2CO3     =     Na2SO4     +     FeCO3. 

The  precipitate  is  whitish  green,  turning  brown-red  by  oxidation. 
To  prevent  this  change  to  the  ferric  condition  sugar  is  used  in  the 
following  official  preparations  which  make  use  of  the  same  reaction 
as  that  given  above: 

Ferri  carbonas  saccharatus  contains  15  per  cent,  of  FeCO3. 
It  is  a  greenish  gray  powder,  sweet  and  ferruginous  in  taste.  Dose: 

2  to  10  gr.  (0.13-0.66  gm.). 

Massa  ferri  carbonatis  (Vallefs  mass)  contains  42  per  cent. 
FeCO3.  It  is  unirritating  and  not  astringent.  Dose:  3  to  5  gr. 
(0.20-0.33  gm.)- 


344  THE    METALS 

Mistura  ferri  composita  (Griffith's  mixture)  contains  ferrous 
carbonate  suspended  in  a  solution  of  potassium  sulphate  with 
sugar  and  rose-water.  Dose:  J  to  i  fl.  oz.  (16-32  c.c.). 

Ferrous  Phosphate  (Fe3(PO4)2).— This  is  formed  when 
sodium  phosphate  is  added  to  ferrous  sulphate  in  the  presence  of 
sodium  acetate.  At  first  white,  it  absorbs  oxygen  and  soon 
assumes  a  blue  color.  It  is  the  source  of  the  slaty-blue  color  of 
pus  and  of  the  lungs  in  phthisis. 

Ferric  phosphate,  FePO4,  is  precipitated  when  ferric  chlorid 
is  added  to  a  solution  of  an  alkali  phosphate.  It  is  official  in  the  ferri 
phosphas  solubilis,  a  soluble  mixture  of  FePO4  with  sodium  citrate. 
Dose:  5  to  10  gr.  (0.33-0.66  gm.). 

Ferri  pyrophosphas  (U.  S.  P.)  is  a  soluble  mixture  in  the  form 
of  scales  containing  ferric  pyrophosphate,  sodium  citrate,  and 
ferric  citrate.  Dose:  i  to  5  gr.  (0.066-0.33  gm.). 

Scale  Compounds. — When  freshly  precipitated  ferric  hydroxid 
is  dissolved  in  citric,  tartaric,  or  other  organic  acid,  double  salts 
are  formed  of  uncertain  composition.  On  evaporating  the  solu- 
tion the  residue  is  not  crystalline.  To  obtain  a  convenient  form 
for  dispensing  the  solution  concentrated  by  evaporation  is  spread 
on  glass  plates  and  dried  at  60°  C.  (140°  F.).  By  tapping  the 
glass  the  thin  coating  is  broken  into  green  or  brown  amorphous 
brilliant  scales,  which  readily  dissolve  in  water.  Among  the 
scale  compounds  are  soluble  iron  phosphate,  iron  and  quinin 
citrate,  iron  and  potassium  tartrate. 

Iron  and  Cyanogen. — These  two  elements  do  not  unite  to 
form  a  ferric  cyanid,  but  combine  in  complex  groups  which  ac1 
as  anions  with  hydrogen  and  the  metals.  As  these  groups  do 
not  show  the  chemical  or  poisonous  properties  of  cyanids  noi 
respond  to  the  usual  tests  for  iron,  it  is  plain  that  they  do  not 
contain  the  ions  of  cyanogen  or  of  iron.  One  of  these  compound 
anions  acting  like  a  single  element  is  called  ferrocyanogen,  and 
its  solution  becomes  ferrocyanidion,  Fe(CN)6"".  It  does  not 
exist  free,  but  is  supposed  to  be  the  constituent  anion  of  hydro- 
jerrocyanic  acid,  H4*,  [Fe(CN)6]"",  and  enters  into  the  compo- 
sition of  metallic  ferrocyanids.  This  tetrabasic  acid  is  prepared 
by  the  action  of  strong  hydrochloric  acid  on  potassium  ferro- 
cyanid.  It  occurs  in  white  scales,  turning  blue  on  exposure  to 
the  air. 

Potassium  Ferrocyanid  (K4Fe(CN)6)  (Yellow  Prussiate  of 
Potash). — This  is  prepared  by  heating  together  nitrogenous  animal 
waste,  scrap  iron,  and  potassium  carbonate.  The  permanent 
lemon-yellow  crystals  are  freely  soluble  and  non-poisonous,  though 
they  form  hydrocyanic  acid  when  heated  with  sulphuric  acid. 
Potassium  ferrocyanid  is  used  to  precipitate  ferrocyanids  from 


IRON  345 

many  metallic  salts,  giving  in  acid  solutions  of  cobalt  a  yellowish 
green  precipitate;  of  uranium,  a  brown;  of  copper,  a  chocolate; 
of  barium,  a  yellowish  white;  and  a  white  precipitate  from  zinc, 
nickel,  tin,  cadmium,  lead,  antimony,  bismuth,  silver,  mercury, 
and  manganese.  With  ferrous  salts  it  yields  white  precipitates; 
passing  from  light  blue  to  dark  blue;  with  ferric  salts  dark  blue 
ferric  ferrocyanid. 

The  ion  Fe"  is  precipitated  from  ferrous  solutions  by  hydrogen 
sulphid,  but  is  not  precipitated  by  this  reagent  from  the  solutions 
of  potassium  ferrocyanid,  since  on  dissolving  this  salt  the  complex 
ferrocyanidion  [Fe(CN)J////  is  formed  and  not  diferrion  Fe**. 

Ferric  ferrocyanid,  Fe4[Fe(CN)6]3,  is  a  highly  valued  pigment 
known  commercially  as  Prussian  blue.  It  is  formed  whenever 
triferrion,  Fe*",  meets  ferrocyanidion;  and  as  the  dark  blue  color 
is  recognizable  in  very  small  quantities,  it  makes  a  very  sensitive 
reaction  for  ferric  salts. 

Ferricyanogen  is  a  hypothetic  group  not  existing  free,  but 
present  as  anion  in  hydroferricyanic  acid,  H3*,  [Fe(CN)6]"',  and 
metallic  ferricyanids.  The  anion  has  the  same  composition  as  in 
ferrocyanids,  but  differs  in  being  trivalent,  while  ferrocyanidion  is 
tetravalent.  Like  the  latter,  ferricyanidion  exhibits  none  of  the 
chemical  or  physiologic  properties  of  either  cyanogen  or  iron. 

Hydrojerricyanic  acid,  H3Fe(CN)6,  can  be  obtained  from  solu- 
tions of  its  salts,  in  brown  needles,  by  the  action  of  strong  hydro- 
chloric acid.  It  is  tribasic. 

Potassium  ferricyanid,  K3Fe(CN)6  (red  prussiate  of  potash), 
is  prepared  from  the  ferrocyanid  by  treating  it  with  oxidizing 
agents,  such  as  chlorin: 

K4Fe(CN)6      +      Cl  K3Fe(CN)6      +      KC1. 

Garnet  red  crystals  separate  as  the  solution  is  concentrated. 
The  dry  crystals  are  permanent,  but  the  solution  is  unstable  and 
must  be  made  fresh  when  used  as  a  reagent.  With  neutral  solu- 
tions of  metallic  salts  it  yields  precipitates  which  differ  in  color  from 
those  given  by  potassium  ferrocyanid.  The  most  important  of 
these,  showing  that  the  solution  contains  diferrion,  is  ferrous  ferri- 
cyanid, Fe3[Fe(CN)6]2,  a  bright  blue  precipitate  called  TurnbulVs 
Hue. 

Ferric  sulphocyanate  (Fe(SCN)3)  (thiocyanate)  is  the  cause  of 
the  deep  blood  red  color  formed  when  an  excess  of  potassium 
thiocyanate,  KSCN,  is  added  to  solution  of  a  ferric  salt.  The 
most  pronounced  reaction  is  obtained  by  having  a  great  concen- 
tration of  thiocyanate,  which  drives  back  the  relatively  small 
amount  of  triferrion  into  the  red  undissociated  state.  The  effect 


346  THE    METALS 

is  enhanced  by  shaking  .with  ether,  which  dissolves  and  separates 
the  red  undissociated  ferric  thiocyanate. 

Sodium  nitroprussid,  Na2Fe(CN)5NO  .  2H2O,  occurs  in  ruby- 
red  crystals  formed  when  sodium  ferrocyanid  is  treated  with  nitric 
acid.  It  is  used  in  Legal's  test  for  acetone  in  the  urine.  With 
alkaline  sulphids  it  turns  purple. 

Liquor  ferri  acetatis  is  a  33-per  cent,  aqueous  solution  of 
normal  ferric  acetate,  Fe(C2H3O2)3.  It  is  a  deep  red,  transparent 
liquid  of  acetous  odor  and  sweet  ferruginous  taste.  It  is  used  to 
prepare  tinctura  Jerri  acetatis,  which  has,  in  addition  to  the  above, 
alcohol  and  acetic  ether. 

Liquor  jerri  et  ammonii  acetatis,  or  Basham's  mixture,  is  an 
agreeable  preparation  containing  tincture  of  ferric  chlorid,  ammo- 
nium acetate,  and  acetic  acid  dissolved  in  a  sweetened  elixir  of 
orange.  Dose:  2  to  4  fl.  dr.  (8-16  c.c.). 

Toxicology  of  Iron  Salts.— Although  iron  is  present  in 
the  body,  also  in  food,  and  is  a  frequent  constituent  in  tonic  med- 
icines, yet  sufficient  evidence  exists  that  at  least  two  of  its  salts, 
ferrous  sulphate  and  ferric  chlorid,  have  toxic  properties  when 
taken  in  excessive  doses.  Diarrhea  and  abdominal  pain  mark  the 
course  of  a  gastro-enteritis. 

The  widely  used  preparation  tinctura  jerri  chloridi,  or  "tincture 
of  iron,"  a  brown  acid  liquid,  is  frequently  mistaken  for  harmless 
liquids  of  the  same  color.  It  has  been  taken  in  toxic  doses  as 
an  abortifacient. 

Symptoms. — When  ferric  chlorid  has  been  given  experimentally 
to  the  lower  animals  with  food  it  has  been  found  harmless  even 
in  considerable  doses.  The  same  amounts  given  fasting  and  in 
alcoholic  solution  have  resulted  in  death  in  from  one  to  sixteen 
hours.  It  causes  an  inky,  metallic  taste,  violent  abdominal  pain, 
vomiting,  diarrhea,  paralysis  of  the  extremities,  suppression  of 
urine,  convulsions,  and  death.  The  feces  are  blackened  by  the 
iron  sulphid  formed. 

Fatal  Dose. — One  case  has  been  reported  of  death  after  five 
weeks  from  a  dose  of  the  chlorid  equal  to  ij  oz.  of  the  "  tincture 
of  iron."  An  ounce  has  caused  vomiting  and  urinary  symptoms. 
On  the  other  hand,  a  man  aged  seventy-two  recovered  from  the 
effects  of  3  oz.  of  the  tincture. 

Treatment. — The  alkaline  bicarbonates  or  the  carbonates  dis- 
solved in  a  large  amount  of  water  or  milk  may  be  swallowed  or 
used  to  wash  out  the  stomach  with  a  pump  or  tube.  The  gastro- 
enteric  symptoms  should  be  treated  by  rest  and  anodynes. 

Postmortem  Appearances. — In  one  case  a  greenish  black, 
fur-like  "mud"  covered  the  tongue,  esophagus,  and  stomach; 
swelling,  congestion,  and  ecchymotic  points  were  the  changes  noted 


MANGANESE  347 

in  the  liver  and  kidneys,  and  hyperemia  marked  the  brain  and  its 
membranes. 

Tests. — Ammonium  sulphid  causes  a  black  precipitate  of  iron 
sulphid  with  solutions  of  ferrous  or  ferric  salts.  It  can  be  used  after 
the  metal  has  been  extracted  from  the  tissue  with  acetic  acid. 
The  equation  for  this  reaction  is: 

FeS04      +      (NH4)2S      =      (NH4)2SO4      +      FeS. 

Redissolving  the  sulphid  in  nitrohydrochloric  acid,  the  iron  will 
yield  to  potassium  ferrocyanid  a  blue  precipitate.  If  the  iron 
solution  is  almost  neutralized  with  ammonia,  then  ammonium 
sulphocyanid  will  give  a  red  color. 

The  analytic  reactions  which  distinguish  diferrion  from  tri- 
ferrion  may  be  summarized  according  to  the  following  scheme, 
using  ferrous  sulphate  for  the  former  and  ferric  chlorid  for  the 
latter.  In  aqueous  solution  the  ferrous  salt  is  light  green  and 
ferric  salt  reddish  brown.  With  the  reagent  named  in  the  first 
column  the  precipitates  yielded  are  stated  in  the  other  columns: 

Reagents.  Ferrous  salts.  Ferric  salts. 

Hydrogen  sulphid.  No  precipitate.  White   precipitate   of   sulphur, 

and    reduction     to     ferrous 
state. 

Ammonium  sulphid.          Black  precipitate.  Black  precipitate. 

Alkalis.  White  precipitate,  turn-      Red-brown  precipitate. 

ing  green. 
Potassium  ferrocyanid.       White  precipitate,  turn-     Prussian-blue  precipitate. 

ing  blue. 

Potassium  ferricyanid.  Dark  blue  precipitate.  Green  color,  but  no  precipitate. 
Potassium  sulphocyanid.  No  precipitate.  Blood-red  color. 

Acid  tannic.  No  change.  Greenish-black,    inky    precipi- 

tate of  ferric  tannate. 

Detection. — Having  digested  the  organic  matters  thoroughly 
in  water  acidulated  with  acetic  acid,  filtered,  evaporated  the  filtrate 
to  dryness,  and  incinerated  the  residue,  the  ash  is  treated  with 
dilute  sulphuric  acid  and  the  solution  tested  as  above  with  am- 
monium sulphid  and  potassium  ferrocyanid.  Determination  of 
poisonous  amounts  must  rest  upon  the  quantity  found  in  the 
organs  in  excess  of  that  normally  present.  The  black  fur  on  th,e 
mucous  membranes  and  the  stains  on  the  clothing  ought  to  yield 
significant  amounts. 

MANGANESE 
Symbol,  Mn.     Atomic  weight,  55. 

Manganese  occurs  in  nature  usually  as  an  oxid,  the  most  abun- 
dant being  pyrolusite,  MnO2.  The  metal  can  be  made  by  elec- 
trolysis of  the  chlorid  or  by  reduction  of  the  oxid  by  heating  with 
carbon  or  with  powdered  aluminium. 


348  THE    METALS 

The  metal  belongs  to  the  iron  group,  because  of  its  similarity 
in  physical  and  chemical  properties.  When  pure  it  is  reddish 
gray  in  color,  lustrous,  and  resists  the  action  of  the  air  fairly  well, 
but  the  impure  form  rusts  more  easily  than  iron  and  has  little 
commercial  value  except  as  an  alloy  of  iron  and  bronze. 

Manganese  Dioxid  (MnO2)  (Black  Oxid  of  Manganese). — Of 
the  seven  oxygen  compounds  this  is  the  only  one  of  much  impor- 
tance. It  is  a  heavy,  black  crystalline  mineral;  its  chief  use  in  the 
arts  being  that  of  an  oxidizing  agent,  as  in  the  manufacture  of 
chlorin  from  hydrochloric  acid  (see  Chlorin,  p.  118).  Com- 
pressed into  a  cylinder  with  carbon  it  is  used  as  the  negative  ele- 
ment of  a  Ledanche  battery  cell  (p.  47).  The  energy  of  this  cell 
is  derived  largely  by  the  loss  of  charges  of  electricity  when  Mn**** 
changes  to  ions  of  lower  valence. 

Ions  of  Manganese. — In  the  case  of  the  dioxid,  manganese  is. 
tetravalent.  The  series  of  salts  of  the  lowest  valence  are  called 
manganous,  in  which  occurs  the  divalent  ion,  Mn".  These  differ 
from  the  ferrous  salts  in  that  their  acid  solutions  do  not  absorb 
oxygen  from  the  air.  Dimanganion  is  distinctly  basic  and  has  a 
pale  reddish  color.  Trivalent  manganese,  Mn'",  is  weakly  basic 
and  occurs  in  the  manganic  compounds  into  which  the  manganous 
pass  by  oxidation.  The  color  of  its  unstable  solutions  is  violet- 
red.  Its  salts  quickly  hydrolyze  into  brown  manganic  hydroxid, 
Mn(OH)3. 

Manganous  Sulphid  (MnS).—  The  pink  precipitate  formed 
when  ammonium  sulphid  is  added  to  a  cold  solution  of  a  man- 
ganous salt  is  a  hydrate  of  manganous  sulphid.  On  standing  it 
becomes  dehydrated  and  changes  to  green  manganous  sulphid. 
This  green  sulphid  is  precipitated  immediately  when  the  man- 
ganous solution  is  hot  and  concentrated. 

Manganous  Sulphate  (MrlSO4 .  4H2O)  (Mangani  Sulphas).— 
This  is  produced  when  oxygen  is  generated  by  the  "wet  way," 
dissolving  manganese  dioxid  in  sulphuric  acid: 

MnO2     +     H2SO4     =     MnSO4     +     H2O     +     O. 

When  purified  from  iron  it  forms  pale  rose-colored  prisms  with 
an  astringent  bitter  taste.  The  crystals  are  soluble  in  water. 
Manganous  sulphate  is  used  as  a  tonic  adjuvant  to  iron.  Dose: 
2  to  5  gr.  (0.13-0.33  gm.). 

Hexavalent  manganese  is  known  in  the  salts  of  manganic 
acid,  H2MnO4,  which  is  regarded  as  formed  from  Mn(OH)6  by 
loss  of  2H2O.  The  acid  itself  is  so  unstable  that  it  does  not 
exist  free,  but  its  salts,  such  as  potassium  manganate,  K2MnO4, 
are  stable  in  alkaline  solutions.  In  acid  or  neutral  solutions  they 
instantly  change  to  salts  of  permanganic  acid.  The  solution  of 


MANGANESE  349 

crude  potassium  manganate  with  some  potash  has  a  green  color, 
but  on  exposure  to  the  air  absorbs  carbon  dioxid,  changes  to 
potassium  permanganate,  KMnO4,  and  passes  from  green  to 
purplish  red  through  violet  and  blue.  This  play  of  colors  gave 
the  substance  the  name  mineral  chameleon: 

3K2MnO4   +    2CO2   =   MnO2   +   2K2CO3   +   2KMnO4 

Potassium  manganate.  Potassium  permanganate. 

Potassium  Permanganate  (KMnOJ.—  This  is  the  purple- 
red  crystalline  product  obtained  on  evaporation  of  the  red  liquid 
just  mentioned  above.  The  anion  here  is  the  univalent  perman- 
ganic ion  (MnO4)',  analogous  to  the  perchloric  (C1O4)'.  In  the 
manganates  the  anion  (MnO4)//  is  divalent.  Permanganic  acid  is 
the  highest  stage  of  oxidation  and  may  be  regarded  as  the  partial 
anhydrid  of  heptavalent  manganese  in  the  hydroxid  Mn(OH)7: 

Mn(OH)7  less  3H2O  HMnO4. 

This  salt  is  a  powerful  oxidizing  agent  for  almost  all  organic 
substances,  and  is  destructive  to  the  low  organisms  of  infectious 
diseases.  Its  solutions  should  not  be  kept  in  contact  with  rubber 
or  cork  nor  filtered  through  paper,  or  the  brown  manganese 
hydroxid  will  form.  The  brown  stains  made  by  it  can  be  removed 
by  oxalic  or  hydrochloric  acid. 

"Condy's  disinfecting  fluid"  is  a  2-per  cent,  solution  of  it  and 
"Darby's  fluid"  also  contains  it. 

With  alkalis  in  the  presence  of  reducing  agents  2  molecules  of 
potassium  permanganate  yield  3  atoms  of  oxygen.  The  decom- 
position is  according  to  this  equation,  in  which  X  is  the  organic 
substance: 

2KMn04    +    5H20    +    X   =    2KOH    +    2Mn(OH)4    +    XO3. 
With  acids  the  salt  yields  to  reducing  agents  5  oxygenations: 


It  oxidizes  oxalic  acid  to  carbon  dioxid  and  water  in  such  exact 
proportions  that  its  solution  is  used  for  volumetric  testing  of  that 
substance,  and  conversely  the  oxalic  acid  is  used  to  standardize 
solutions  of  permanganate  which  tend  to  deteriorate  for  a  short 
length  of  time. 

C2H2O4         +          O  2CO2          +          H2O. 

One  molecule  of  oxalic  acid  requires  one  atom  of  oxygen;  there- 
fore, one  liter  of  normal  solution  of  oxalic  acid  is  exactly  oxidized 
by  a  liter  of  normal  permanganate  solution.  The  oxalic  acid 


35°  THE    METALS 

decolorizes  the  permanganate  until  the  acid  is  all  oxidized;  if  the 
purple  color  persists,  it  shows  plainly  the  end  of  the  reaction. 

The  oxidizing  powers  of  this  salt  are  brought  into  action  when 
it  is  used  as  an  antidote  to  the  poisonous  alkaloids,  with  which  it 
reacts  more  promptly  than  with  the  usual  gastric  contents.  As 
an  antidote  i  or  2  gr.  are  given  dissolved  in  i  pt.  of  water,  and 
then  removed  by  the  stomach-tube  or  emetics.  When  admin- 
istered in  pills  the  excipient  should  be  unoxidizable  substance,  such 
as  kaolin  and  petrolatum.  It  decomposes  alcohol  and  oxidizes 
glycerin  and  turpentine  with  a  rapidity  that  is  almost  explosive. 
The  other  incompatible*  are  organic  substances,  alkaloids,  acids, 
charcoal,  carbolic  acid,  chlorids,  bromids,  arsenites,  mercurous 
and  ferrous  salts,  ammonia,  hydrogen  dioxid,  sulphites  and  hypo- 
sulphites, also  phosphites  and  hypophosphites. 

Tests  for  Manganese  Salts.— With  ammonium  sulphid,  man- 
ganous  sulphate  yields  a  flesh-colored  precipitate  soluble  in  acids. 

With  ammonium  or  sodium  hydroxid  there  results  a  white 
manganous  hydroxid  which  oxidizes  in  the  air  to  a  brownish 
color  and  dissolves  pink  in  oxalic  acid. 

A  small  portion  of  gray  manganese  compound  placed  on  plat- 
inum foil  and  heated  with  a  mixture  of  sodium  nitrate  and  car- 
bonate, fuses  to  make  sodium  manganate,  which  yields  a  green 
aqueous  solution,  changing  to  red  on  the  addition  of  an  acid. 


CHROMIUM 

Symbol,  Cr.     Atomic  weight,  52. 

This  is  a  white,  hard,  crystalline  metal  of  difficult  fusibility. 
Though  readily  attacked  by  alkalis,  it  resists  all  acids  except 
hydrochloric.  It  forms  salts  of  divalent  dichromion,  Cr",  called 
chromous,  and  of  trivalent  trichromion,  Cr"*,  called  chromic. 

The  ion  of  chromous  compounds  is  blue  and  strongly  reducing 
in  its  effect,  passing  into  the  ion  of  chromic  salts. 

Chromium  hydroxid,  Cr(OH)3,  is  a  green  precipitate  formed 
when  ammonia  acts  on  solutions  of  green  chromic  salts.  It  dis- 
solves in  excess  of  the  alkali  to  a  green  liquid.  One  of  the 
hydroxids  is  known  as  chromium  green,  Cr2O(OH)4,  an  emerald 
pigment  used  in  the  arts;  it  is  non-poisonous. 

Chromic  oxid  (Cr2O3)  (sesqui-oxid)  is  green,  insoluble,  and 
is  not  easily  fused  or  decomposed  by  heat.  With  alkaline 
hydroxids  and  nitrates  it  forms  chromates  in  two  series:  one 
green,  the  other  violet.  The  hydroxid  formed  by  alkalis  from  the 
violet  salt  is  violet  in  color. 

Chromanion. — Heated  in  the  air  with  strong  bases,  chromium 
compounds  take  up  oxygen  and  form  chromates.  These  are  salts 


CHROMIUM  351 

of  a  bivalent  anion  (CrO4)//,  which  is  isomorphous  with  sulphanion, 
(804)".  This  chromanion  imparts  its  yellow  color  to  its  salts; 
such  as  the  potassium  chromates  and  lead  chromate. 

Chromic  anhydrid,  CrO3,  with  water  forms  true  chromic  acid, 
H2CrO4.  In  this  acid  the  chromium,  like  the  manganese  in  man- 
ganic acid,  has  the  valence  of  six,  and  in  HCrO5,  perchromic  acid, 
a  yet  higher  valence.  A  solution  of  potassium  dichromate  and 
sulphuric  acid  treated  with  a  few  drops  of  hydrogen  dioxid  is 
oxidized  and  yields  the  transient  blue  color  of  perchromic  acid, 
which  changes  quickly  as  it  evolves  oxygen.  But,  shaken  with 
ether,  the  blue  color  persists  longer  in  the  separate  ethereal  extract 
(p.  89). 

Potassium  chromate  (K2CrO4)  (neutral  chromate)  is  sulphur 
yellow,  crystalline,  and  soluble.  Its  aqueous  solution  is  alkaline. 
When  any  acid  containing  hydrion  is  added,  the  color  changes  from 
yellow  to  orange,  and  the  salt  that  crystallizes  out  is  the  dichromate,, 
K2Cr2O7. 

2K2Cr04    +     H2S04  H20     +     K2SO4    +     K2Cr2O7. 

Chromanion  (CrO4)"  is  changed  to  dichromanion  (Cr2O7)"  as 
indicated  in  this  equation: 

2(Cr04)"     +     H-     +     H-  H20     +      (Cr2O7)". 

Potassium  dichromate,  K2Cr2O7,  occurs  in  orange-red  sol- 
uble crystals  used  by  dyers  and  furniture  stainers.  Operatives 
in  chemical  works  find  that  in  the  shape  of  fine  aerial  particles  it 
irritates  the  respiratory  passages,  sets  up  ozena,  and  causes  erup- 
tions and  excoriations  leading  to  chronic  ulcers. 

Chromium  trioxid  (CrO3)  (chromic  acid,  chromic  anhydrid)  is 
prepared  by  the  action  of  sulphuric  acid  on  saturated  solution  of 
potassium  dichromate: 

K2Cr207    +     H2S04  K2S04     +     2CrO3     +     H2O. 

It  occurs  in  crimson  prismatic  needles,  deliquescent,  freely 
soluble,  and  in  strong  solution  is  acid  and  acts  on  organic  matter 
with  energy.  This  violent  reaction  with  organic  matter  is  the 
basis  of  the  usual  caution  against  using  cork  stoppers  or  mixing 
it  with  alcohol,  ether,  or  glycerin.  It  is  also  incompatible  with 
arsenous  acid,  chlorids,  bromids,  iodids,  sulphids,  oxalates,  sul- 
phites, and  tartrates.  Its  only  use  in  medicine  is  external,  as 
a  deep  caustic  to  the  tonsils,  and  to  papillary  growths.  When 
applied  to  fungous  growths  in  the  mouth  a  portion  is  sometimes 


352  THE    METALS 

accidentally  swallowed.  It  causes  an  acrid  taste  and  burning  in 
the  throat,  with  persistent  vertigo,  vomiting  of  a  ropy  green  fluid, 
and  great  prostration.  In  such  cases  chromium  is  found  in  the 
urine.  Even  its  external  use  is  attended  with  danger.  One 
application  of  about  50  gr.  in  J  oz.  of  water  was  made  to  the  exter- 
nal genitals  of  a  woman  after  removal  of  papillary  vegetations..  In 
twenty-seven  hours  she  died  in  a  state  of  collapse.  Congestion  of 
the  kidneys  and  liver  was  found,  and  both  organs  contained 
chromium. 

Toxicology. — Toxic  effects  have  resulted  from  potassium 
dichromate,  from  chromium  trioxid,  and  from  lead  chromate. 
As  the  poisonous  properties  of  lead  chromate,  chrome  yellow,  are 
mainly  due  to  the  lead  contained  in  it,  they  are  properly  considered 
under  the  compounds  of  lead  (p.  325). 

Symptoms. — When  swallowed,  the  compounds  of  chromium 
act  as  gastro-intestinal  irritants,  with  additional  effects  upon  the 
central  nervous  system.  They  cause  a  disagreeable  taste,  vomit- 
ing, pain,  diarrhea,  collapse,  unconsciousness,  dilated  pupils,  very 
slow  respirations,  and  muscular  cramps. 

Fatal  Dose. — Death  has  occurred  in  fourteen  hours  from  about 
3  dr.  of  potassium  dichromate,  while,  on  the  other  hand,  there  has 
been  a  case  of  recovery  from  273  gr. 

Fatal  Period. — Death  from  i  oz.  has  occurred  in  forty  minutes. 

Treatment. — Chalk  or  magnesia  should  be  given  to  neutralize 
the  acid.  Milk  may  be  administered  or  used  to  wash  out  the 
stomach  with  the  pump  or  tube.  Anodynes  are  indicated  for  the 
pain,  cerebral,  and  respiratory  stimulants  for  the  depression  of  the 
nervous  system. 

Postmortem  Appearances. — Chromic-acid  preparations  are 
absorbed  with  great  rapidity  both  by  stomach  and  skin,  and  its 
elimination  is  mainly  by  the  kidneys,  but  to  some  extent  by  the 
liver  and  bowels.  In  acute  cases  death  is  caused  by  respiratory 
arrest  or  central  nervous  disturbance.  In  the  gastro-intestinal 
tract  are  found  inflammation,  ecchymoses,  and  swollen  follicles. 
An  early  morbid  change  is  parenchymatous  nephritis;  the  spleen 
is  shrunken  and  the  blood  altered. 

Tests  for  Chromium  Salts.— Soluble  chromates  yield  with 
silver  nitrate  a  red  precipitate;  with  lead  nitrate,  a  yellow  precipi- 
tate; with  boiling  dilute  sulphuric  acid  and  alcohol,  a  green  color 
and  the  odor  of  aldehyd. 

When  hydrogen  snip  hid  is  added  to  an  acid  solution  of  a  chro- 
mate, sulphur  is  precipitated  and  the  red  color  changes  to  green 
from  the  formation  of  a  basic  chromium  salt  of  the  acid.  When 
ammonium  hydroxid  is  added  to  this  green  solution  the  hydroxid 
O(OH)3  is  precipitated  as  a  bluish  green  jelly. 


ZINC  353 

Ammonium  sulphid  causes  the  same  green  precipitate  from  a 
solution  of  any  salt  of  chromium,  such  as  the  chlorid  or  sulphate. 

Detection. — Having  treated  organic  matters  with  hydro- 
chloric acid  and  potassium  chlorate,  the  liquid  turns  green  from 
chromic  chlorid.  Ammonium  hydroxid  added  to  the  filtered 
liquid  in  slight  excess  will  yield  hydrated  chromic  oxid  as  a  pre- 
cipitate, which,  after  washing  and  drying,  can  be  converted  into 
potassium  chromate  by  fusing  with  potassium  nitrate  and  car- 
bonate. After  dissolving  the  fused  mass  (which  will  be  more  or 
less  yellow  in  color  if  chromium  be  present)  in  water  and  making 
slightly  acid  with  acetic  acid,  the  chromate  can  be  detected  by 
the  tests  given  above. 

ZINC 

Symbol,  Zn.     Atomic  weight,  65.4. 

Occurrence. — This  metal  occurs  abundantly  in  nature  as  car- 
bonate, silicate,  and  sulphid  (blende).  Reduced  by  heating  with 
charcoal,  the  free  metal  distils  into  receivers  from  which  air  is 
excluded. 

Properties.— It  is  a  white,  rather  soft  metal,  melting  at  410°  C. 
(760°  F.),  and  at  a  bright-red  heat  volatilizing  and  burning. 
Commercial  zinc  often  contains  a  trace  of  arsenic.  In  either 
air  or  water  it  first  oxidizes  and  later  forms  a  coherent  coat  of 
hydroxid  and  carbonate  which  protects  the  metal  underneath. 
This  coat  does  not  dissolve  in  water  unless  the  water  contain 
chlorids.  If  heated  to  over  100°  C.  (212°  F.)  the  brittle  metal 
softens  and  can  be  rolled  into  sheet  zinc  which  retains  its  tenacity 
at  common  temperatures.  This  is  the  form  generally  used  in  the 
arts.  To  protect  iron  sheets,  tubes,  and  implements  they  are 
given  a  coat  of  zinc.  Iron  so  treated  is  called  galvanized  iron. 
This  superficial  covering  of  zinc  with  its  hydroxid  makes  the  iron 
more  durable.  Zinc  is  a  constituent  of  brass  and  German  silver. 

The  Ion  of  Zinc. — This  metal  resembles  iron,  manganese,  and 
chromium  in  many  respects,  but,  unlike  those  metals,  it  has  but  one 
valence.  Zincion,  Zn",  is  divalent  and  white,  like  magnesion. 
Owing  to  the  prevalence  of  the  metal  in  certain  soils  it  is  sometimes 
found  in  plants,  and  in  consequence,  traces  are  occasionally  dis- 
covered in  plant-fed  animal  tissues.  Zinc  has  been  found  in  the 
liver  of  cadavers  under  circumstances  which  precluded  the  pos- 
sibility of  poisoning,  since  the  clinical  history  presented  no  symp- 
toms attributable  to  the  metal  deposited. 

Zinc  Oxid  (ZnO)   (Zinci   Oxidum,  Zinc  White). — By  burning 
the  metal  in  the  air  the  pigment  zinc  white  is  prepared.     As  com- 
pared with  white  lead,  it  is  less  poisonous  and  does  not  darken 
by  hydrogen  sulphid,  but  it  has  less  covering  power. 
23 


354  THE    METALS 

It  is  a  soft  white  powder,  permanent,  odorless,  tasteless,  and 
insoluble.  Dose:  i  to  10  gr.  (0.066-0.66  gm.). 

Unguentum  zinci  oxidi  contains  20  per  cent,  zinc  oxid. 

Zinc  hydroxid,  Zn(HO)2,  is  the  white  precipitate  formed  when 
sodium  or  ammonium  hydroxid  is  added  to  solutions  of  zinc 
salts.  A  base  added  in  excess  redissolves  the  deposit.  In  the 
presence  of  much  alkali,  Zn  (HO)2  splits  off  hydrion  from  the 
hydroxyl: 

Zn(HO)2  H',  H-,  (ZnO2)". 

Hydrion  gives  it  acid  properties  and  a  soluble  sodium  zincate, 
Na2ZnO2,  is  formed: 

Zn(HO)2     +     2NaHO     =     Na2ZnO2     +      2H2O. 

In  the  presence  of  acids  containing  hydrion  it  dissociates  in  a 
different  sense: 

Zn(HO)2  Zn-,  2(HO)'. 

All  acids  combine  with  the  zincion  to  form  the  corresponding 
zinc  salt. 

Zinc  Carbonate  (ZnCO3)  (Zinci  Carbonas  Pracipitatus).— 
When  solutions  of  zinc  salts  are  boiled  with  solution  of  an  alkaline 
carbonate  a  white  precipitate  of  a  basic  carbonate  forms,  contain- 
ing hydroxid. 

Zinc  phosphid  (Zn3P2)  (zinci  phosphidum)  is  a  gray-black 
powder  formed  when  phosphorus  is  thrown  upon  melted  zinc.  It 
>is  insoluble  in  water  and  alcohol.  Dose:  -£$  to  •$-$  gr.  (0.0013- 
0.003  gm.). 

Zinc  Acetate  (Zn(C2H3O2)2,  3H2O). — By  the  action  of  acetic 
acid  on  the  metal  soft  white  scales  are  produced.  These  are 
soluble,  efflorescent,  metallic  in  taste,  with  an  acetous  odor.  The 
aqueous  solution,  2  gr.  to  i  fl.  oz.,  is  used  as  a  local  astringent. 

Zinc  in  Food. — Zinc  is  soluble  in  the  weak  acids  of  foods. 
The  well-known  fact  that  milk  keeps  sweet  longer  in  zinc  vessels 
than  in  pots  is  explained  by  the  neutralization  of  lactic  acid  by 
the  zinc,  which  is  taken  up  as  a  lactate.  Not  only  may  milk  thus 
be  contaminated,  but  also  vinegar,  soup,  olive  oil,  and  alcoholic 
liquids.  The  symptoms  produced  by  articles  of  food  thus  con- 
taminated are  not  grave,  and  the  effects  of  zinc  oxid  upon  those 
who  work  in  zinc  factories  are  so  inconspicuous  as  hardly  to 
deserve  the  name  of  poisonous.  The  "zinc  fever"  sometimes 
seen  in  workers  in  brass  and  other  foundries  where  zinc  is  vapor- 
ized and  inhaled  is  marked  by  indigestion,  headache,  colic,  diarrhea, 


ZINC  355 

cramps  in  the  legs,  and  peripheral  neuritis,  symptoms  which  might 
be  attributable  to  the  arsenic  which  is  usually  present  in  commer- 
cial zinc.  Of  the  small  amounts  sometimes  contained  in  drinking 
water  stored  in  galvanized  pipes  and  tanks,  without  doubt  only 
a  minute  proportion  is  absorbed  and  that  is  soon  eliminated. 
When  larger  doses  have  been  taken  repeatedly  the  metal  has  been 
found,  in  the  liver  and  as  an  excretion  in  the  bile  of  the  gall-bladder. 
As  regards  toxicity,  pure  zinc  salts  are  classed  with  those  of  copper 
and  not  with  the  slowly  cumulative,  metallic  poisons,  arsenic, 
antimony,  mercury,  and  lead. 

Poisonous  Salts. — Of  65  cases  of  acute  zinc-poisoning,  all 
were  caused  by  the  two  soluble  salts,  the  sulphate  and  the  chlorid. 
The  sulphate  was  to  blame  in  25  cases,  of  which  8  were  due  to 
mistaking  it  for  "  Epsom  salt."  Zinc  chlorid  was  the  poison  in 
40  cases.  The  form  used  in  26  cases  was  "  Burnett's  Disinfec- 
tant;" in  4  it  was  "  soldering  fluid." 

Zinc  Sulphate  (ZnSO47H2O)  (White  Vitriol).— This  salt  can  be 
made  by  the  action  of  sulphuric  acid  on  zinc,  or  by,  heating  the 
sulphid  in  the  presence  of  oxygen: 

ZnS          +          2O2  ZnSO4. 

It  is  metallic  in  taste,  freely  soluble,  and  occurs  in  crystals  so 
closely  resembling  magnesium  sulphate  that  it  is  often  mistaken  for 
it.  The  zinc  salt  is  sometimes  kept  in  the  household  as  a  prompt 
emetic  for  emergencies.  " Epsom  salt"  is  also  a  domestic  remedy, 
and  both  are  often  kept  in  the  same  closet  in  loose  packages  with- 
out labels. 

These  facts  account  for  the  frequency  with  which  accidental 
poisoning  occurs.  In  doses  of  20  or  30  gr.  zinc  sulphate  will 
evacuate  the  stomach  without  causing  much  depression.  This 
effect  is  so  constant  that  even  after  doses  of  i  oz.  are  taken  re- 
covery is  the  rule.  When  complete  expulsion  does  not  occur  it 
acts  as  a  gastro-intestinal  irritant,  causing  vomiting,  purging,  and, 
secondarily,  dangerous  prostration.  In  i  case  there  was  neither 
vomiting  nor  purging,  but  death  occurred  in  less  than  four  hours 
from  the  depressing  action  on  the  nervous  system. 

Zinc  chlorid,  ZnCl2,  is  readily  formed  by  dissolving  zinc  in 
hydrochloric  acid  and  concentrating  the  solution  by  evaporation 
until  it  crystallizes.  It  is  a  very  soluble,  deliquescent  salt,  present 
in  Burnett's  Disinfectant,  also  in  the  embalming  fluid  used  for 
preserving  bodies  for  dissection.  It  is  a  dehydrating  agent,  con- 
densing and  hardening  the  tissues.  When  zinc  oxid  is  dissolved 
in  a  concentrated  solution  of  zinc  chlorid,  an  oxychlorid,  ZnOHCl, 
crystallizes  in  a  hard  mass.  A  similar  and  less  irritating  oxy- 
phosphate  forms  when  the  oxid  is  dissolved  in  glacial  phosphoric 


356  THE    METALS 

acid.  For  dental  purposes  the  plastic  paste  is  put  into  cavities, 
where  it  rapidly  hardens.  It  is  a  valuable  cement. 

A  soldering  fluid  is  made  extemporaneously  by  dissolving  zinc 
to  saturation  in  hydrochloric  acid.  This  fluid  is  used  to  cleanse 
the  surface  of  metals,  so  that  the  solder  can  make  a  perfect  joint. 
In  the  shape  of  fused  caustic  sticks  the  chlorid  is  used  to  transfix 
cancerous  tumors,  the  effect  being  to  disorganize  the  growth  for 
a  considerable  area,  as  the  salt  absorbs  water  from  the  tissues  and 
diffuses  readily.  It  is  sometimes  applied  as  a  paste  by  cancer 
quacks  in  so  careless  a  manner  as  to  cause  death.  This  external 
application  to  the  breast  may  produce  general  symptoms  of  poi- 
soning by  zinc,  and  the  metal  be  found  in  the  liver  and  other 
organs. 

Symptoms  jrom  Zinc  Chlorid. — The  gastro-intestinal  symptoms 
are  those  of  a  powerful  corrosive — a  metallic  taste  with  instant 
burning  pain  in  mouth,  throat,  and  stomach.  The  act  of  swal- 
lowing is  difficult  and  painful,  and  the  salivary  flow  excessive. 
Violent  vomiting  begins  immediately,  often  of  bloody  matters; 
purging  supervenes,  with  tenesmus  and  bloody  stools.  Collapse 
may  end  in  coma  and  death  in  a  few  hours.  If  life  be  prolonged, 
nervous  sequelae  are  common,  such  as  perversion  of  the  special 
senses,  localized  muscular  spasms,  muscular  weakness,  and  aphonia. 
The  local  action  may  cause  stricture  of  the  gullet  or  pylorus,  and 
also  destruction  of  the  glandular  structure  of  the  stomach,  thus 
impairing  digestion,  so  that  inanition,  extreme  wasting,  and  even 
death  may  ensue. 

Fatal  Dose. — The  prompt  emetic  action  of  zinc  sulphate  has 
brought  about  recovery  after  doses  of  i  oz.;  death  has  ensued  from 
taking  ij  oz.  The  caustic  action  of  zinc  chlorid  has  caused 
death  secondarily  after  several  weeks  from  the  administration  of 
6  gr.  Recovery  has  been  brought  about  after  a  dose  of  200  gr. 

Fatal  Period. — While  death  has  occurred  in  about  four  hours 
from  administration  of  zinc  sulphate  without  vomiting,  and  in 
another  case  from  zinc  chlorid,  yet  there  are  instances  of  death 
from  the  secondary  effects  of  disorganization  of  the  stomach  and 
stricture  of  the  gullet  as  late  as  one  hundred  and  sixteen  days 
after  the  dose. 

Treatment.— The  efforts  of  the  stomach  at  evacuation  must  be 
assisted  by  free  drafts  of  warm  water  or  warm  milk.  The  stom- 
ach-tube may  be  used  in  the  very  exceptional  cases  when  emesis 
is  not  prompt.  The  antidotes  are  milk,  eggs,  and  the  vegetable 
astringents  containing  tannin,  represented  by  strong  decoctions  of 
green  tea. 

Postmortem  Appearances. — The  usual  consequences  of  irri- 
tant poisoning,  more  or  less  intense,  are  to  be  seen — that  is,  con- 


NICKEL COBALT  357 

gestion  in  the  mouth,  gullet,  stomach,  and  intestines;  areas  of 
softening,  ulceration,  and  even  perforation.  When  death  is  due 
to  secondary  starvation,  there  is  usually  narrowing  of  the  gullet, 
with  thickening  and  corrugation. 

Tests  for  Zinc  Salts.— Hydrogen  Sulphid  Tests.— A  stream 
of  this  gas  precipitates  white  zinc  sulphid  from  an  alkaline  or 
neutral  solution,  or  a  solution  made  acid  by  acetic  acid.  This 
precipitate  is  soluble  in  the  mineral  acids,  but  insoluble  in  acetic 
acid,  the  alkalis,  and  the  alkaline  sulphids. 

Ammonium  sulphid  gives  the  same  precipitate,  the  only  white 
insoluble  sulphid  obtained  by  this  procedure. 

Potassium  ferrocyanid  can  be  used  to  distinguish  zinc  sulphate 
from  magnesium  sulphate  and  oxalic  acid,  both  of  which  have 
been  mistaken  for  it.  White  zinc  ferrocyanid  is  thrown  down 
from  a  solution  containing  zinc  sulphate,  but  the  two  others  yield 
no  precipitate. 

Detection. — Organic  matters  supposed  to  contain  zinc  may 
be  digested  at  a  gentle  heat  with  dilute  acetic  acid,  filtered,  the 
filtrate  concentrated,  and  the  metal  thrown  down  as  sulphid  by  a 
stream  of  hydrogen  sulphid.  This  precipitate,  collected  on  a 
filter,  is  washed,  dissolved  in  strong  nitric  acid,  evaporated  to  dry- 
ness,  the  residue  taken  up  with  water,  and  precipitated  as  a  hydra- 
tocarbonate  by  adding  sodium  carbonate  and  boiling  thoroughly. 
Having  filtered  and  washed  the  precipitate,  it  can  be  dried,  ignited, 
and  weighed  as  ZnO.  A  small  portion  of  the  hydrated  carbonate 
may  be  fused  on  platinum  with  a  drop  of  cobalt  nitrate.  The 
zinc  is  detected  by  the  green  color  resulting. 

NICKEL  COBALT 

Symbol,  Ni.     Atomic  weight,  58.7.  Symbol,  Co.     Atomic  weight,  59. 

These  metals  belong  to  the  iron  group,  their  sulphids  being 
soluble  in  acids. 

Nickel. — German  silver  is  an  alloy  of  nickel,  zinc,  and  copper. 
Alloys  of  nickel,  25  per  cent.,  and  copper,  75  per  cent.,  are  widely 
used  for  coins  of  lower  value.  For  this  it  is  fitted  by  its  hardness, 
malleability,  and  resistance  to  the  action  of  air.  Nickel-plating  is 
much  used  to  protect  iron  from  rust.  None  of  the  salts  of  this 
metal  are  used  in  medicine. 

The  Ion  of  Nickel. — In  its  stable  compounds  the  element  is 
present  as  the  divalent  nickelion,  Ni",  which  imparts  a  green 
color  to  solutions  containing  it. 

Cobalt,  like  iron,  melts  at  a  high  temperature,  becomes  coated 
with  oxid  in  moist  air,  decomposes  water  at  a  red  heat,  and  dis- 
solves in  the  strong  mineral  acids.  Like  iron,  also,  it  forms  two 


358  THE    METALS 

series  of  salts,  in  the  cobaltous  occurs  the  divalent  ion,  Co";  in 
the  cobaltic,  the  trivalent  ion,  Co'".  The  chief  use  of  cobalt  in 
the  arts  is  to  impart  a  dark-blue  color  to  glass  and  porcelain  by 
fusion  with  the  silicates. 

Tests  for  Nickel  and  Cobalt. — Ammonium  sulphid  yields 
a  black  precipitate  with  salts  of  both  metals.  Ammonium  hy- 
droxid  causes  a  deposit  of  hydroxids,  soluble  in  excess;  that  of 
nickel  being  green,  that  of  cobalt  blue.  The  hydroxids  thrown 
down  by  potash  and  soda  have  similar  colors  to  those  caused  by 
ammonium  hydroxid,  but  are  not  dissolved  by  excess  of  the  base. 


VIL— THE  GOLD  GROUP 

IN  this  group  are  gold,  platinum,  and  molybdenum,  heavy 
metals  whose  sulphids  are  insoluble  in  water  and  dilute  acids,  but 
soluble  in  ammonium  sulphid. 

GOLD    (Aurum) 
Symbol,  Au.     Atomic  weight,  197.25. 

As  gold  is  found  free  and  untarnished  in  nature,  not  combining 
with  oxygen  of  the  air  at  any  temperature,  it  is  classed  writh  plati- 
num and  silver  as  a  noble  metal.  As  a  tellurid  it  is  found  in  the 
combined  state. 

On  account  of  the  high  specific  gravity  of  this  element  (19.3) 
it  can  be  separated  from  earth,  crushed  rock,  and  sand  by  me- 
chanical washing.  To  separate  washed  gold  from  impurities  it  is 
first  treated  with  mercury,  with  which  it  amalgamates,  and  then, 
on  being  distilled,  the  gold  remains  in  the  retort. 

When  combined,  as  in  the  tellurid,  the  cyanid  chemical  process 
is  used.  The  finely  crushed  ore  is  treated  with  potassium  cyanid, 
which  dissolves  out  the  gold  as  a  double  cyanid,  potassium  auri- 
cyanid,  KAu(CN)4.  This  salt  has  potassium  as  cation,  and  for 
anion  a  group,  aurocyanidion.  Metallic  zinc  or  electrolysis  can 
be  used  to  set  the  gold  free  from  the  other  elements. 

Properties. — Gold  is  a  soft  metal,  orange  yellow  by  reflected 
light,  green  by  transmitted  light  and  when  molten.  It  melts  at 
1200°  C.  (2192°  F.)  and  is  a  good  conductor  of  heat  and  elec- 
tricity. Being  very  malleable,  it  can  be  hammered  into  a  thin 
translucent  foil.  Cohesive  gold,  used  by  dentists  to  fill  teeth,  is 
made  by  heating  gold  foil  to  redness,  thus  restoring  a  property 
of  cohering  lost  when  the  foil  was  beaten  out  thin.  It  resists  the 
chemical  action  of  the  strong  acids  singly,  but  is  dissolved,  as  stated 
above,  by  mercury  and  the  cyanids,  and  also  by  chlorin-water, 


PLATINUM  359 

nitromuriatic  acid,  alkaline  hydroxids,  and  nitrates.  To  render 
it  hard  enough  for  daily  use  it  is  alloyed  with  silver  and  copper. 
Pure  gold  is  said  by  the  mints  to  be  1000  fine,  by  jewelers  24 
carats  fine;  if,  however,  the  alloy  has  only  75  per  cent,  of  gold,  it 
is  iS-carat  gold,  the  other  6  parts  being  copper  and  silver. 

The  Ions  of  Gold. — The  soluble  salts  of  gold  are  trivalent, 
forming  the  ion  Au*",  and  are  called  auric.  There  are  other 
compounds,  known  as  aurous,  which  contain  the  metal  as  a  mono- 
valent  element.  When  an  atom  of  gold  meets  the  undissociated 
chlorin  of  chlorin-water,  the  electric  interaction  causes  the  former 
to  be  ionized  to  a  cation  and  the  latter  to  anions,  while  the  dis- 
sociated gold  chlorid  dissolves. 

Au     +     Cl    +     Cl    +     Cl    =     Au— ,  Cl',  Cl',  Cl'. 

This  is  the  third  mode  of  ion  formation,  consisting  in  the  simul- 
taneous charging  of  electricity  by  the  contact  of  dissimilar  atoms. 

Gold  chlorid  is  prepared  by  dissolving  pure  gold  in  nitro- 
mUriatic  acid.  From  this  yellow  solution,  by  careful  evaporation, 
yellow  crystals  are  obtained  of  hydrochloroauric  acid,  HAuCl4. 
Stronger  heat  drives  off  HC1  and  leaves  soluble,  deliquescent, 
brown  crystals  of  gold  trichlorid,  AuCl3. 

Auri  et  sodii  chloridum,  NaAuCl4 .  2H2O,  is  an  orange-yellow 
soluble  powder  prepared  from  equal  parts  of  gold  chlorid  and 
sodium  chlorid.  It  is  one  of  a  large  series  of  double  salts  obtained 
by  the  action  of  the  solution  of  hydrochloroauric  acid  on  salts, 
especially  chlorids.  The  chlorid  of  gold  and  sodium  is  used  in 
medicine  as  a  tonic,  and  also  in  photography  as  a  wash  to  give 
a  brown-violet  tone  of  reduced  gold.  Dose:  sV  to  -fa  gr.  (0.002- 
0.006  gm.). 

Its  toxic  effects  are  similar  to  those  of  mercuric  chlorid — i.  e., 
gastro-enteritis,  mental  disturbances,  and  convulsions.  The  treat- 
ment is  by  eggs  and  other  albuminous  substances. 

Tests. — Hydrogen  sulphid  yields  a  dark  brown  precipitate  of 
auric  sulphid,  Au2S3,  which  is  insoluble  in  acids,  but  soluble  in 
yellow  ammonium  sulphid.  With  ferrous  sulphate  a  brown  pow- 
der is  deposited,  which  when  dried  and  burnished  shows  the  yellow 
luster  of  gold.  A  similar  reaction  is  obtained  from  other  reducing 
agents,  such  as  sulphurous  acid  and  oxalic  acids. 

PLATINUM 

Symbol,  Pt.     Atomic  weight,  195. 

Occurrence. — This  valuable  element  occurs  in  small  quanti- 
ties in  many  places.  It  is  found  mixed  with  rarer  and  little-used 
metals  of  the  same  group  called  iridium,  osmium,  palladium, 
rhodium,  and  ruthenium. 


360  THE    METALS 

Properties. — Platinum  is  gray  and  silvery  in  color,  with  the 
very  high  specific  gravity  21.4,  It  melts  with  great  difficulty  and 
resembles  gold  in  its  indifference  to  the  strongest  reagents.  It  is 
used  in  the  arts  and  in  the  laboratory  for  crucibles,  dishes,  and 
stills,  resisting  chemicals  and  high  direct  temperatures  better  than 
porcelain.  It  makes  easily  fusible  alloys  with  molten  metals,  and 
is  dissolved  by  nitrohydrochloric  acid  and  hot  alkalis.  The  acids 
nitric,  sulphuric,  hydrochloric,  and  hydrofluoric  have  no  action 
upon  it,  but  it  unites  with  free  chlorin,  and,  at  a  red  heat,  with 
phosphorus  and  sulphur.  Its  ductility  and  malleability  are 
shown  in  the  fine  wire  and  thin  sheets  used  in  the  arts.  It  has  the 
same  co-efficient  of  expansion  as  glass,  and  hence  is  used  to  conduct 
electricity  through  Edison  lamps,  into  which  it  fuses  without  crack- 
ing the  glass. 

When  the  double  chlorid  of  platinum  and  ammonium  is  heated 
the  platinum  is  set  free  not  as  white  metal,  but  as  a  loose  mass 
called  spongy  platinum.  By  chemical  reduction  of  platinum 
compounds  a  finely  divided  form  is  obtained,  known  as  platinum 
black.  Enormous  quantities  of  gases  (several  hundred  volumes 
of  oxygen)  are  absorbed  by  this  fine  powder.  The  reactions  of  the 
absorbed  gases  are  accelerated  to  a  pronounced  degree;  in  this 
way  platinum  is  a  catalyzer,  causing  direct  union  of  hydrogen 
and  oxygen  (pp.  87  and  93). 

The  Ions  of  Platinum. — The  valence  of  platinum  is  exhibited 
in  two  series  of  salts,  divalent  and  tetravalent. 

Platinochlorids. — When  dissolved  in  nitrohydrochloric  acid 
a  yellow  solution  is  obtained,  leaving  on  evaporation  crystals  of 
hydrochloroplatinic  acid,  H2PtCl6.  This  is  used  as  a  reagent  for 
precipitating  potassium  and  ammonium  from  solutions  in  the 
form  of  the  difficultly  soluble  salts  K2PtCl6,  potassium  platino- 
chlorid,  and  (NH4)2PtCl6,  ammonium  platinochlorid.  The  cor- 
responding salt  of  sodium  is  not  precipitated.  These  are  commonly 
called  double  chlorids  of  the  metals. 

Barium  platinocyanid,  BaPt(CN)4 .  4H2O,  is  prepared  by 
passing  hydrocyanic  acid  into  hot  water  containing  platinous 
chlorid  and  barium  carbonate.  Like  the  other  complex  platinum 
compounds  with  cyanogen,  it  is  derived  from  the  divalent  ion 
Pt(CN)4".  The  light  yellow  crystals  are  iridescent,  with  a  green- 
ish violet  light.  Fluorescent  screens  are  made  from  it,  which  have 
the  power  of  making  ultraviolet  rays — radium  and  uranium 
radiations  and  Rontgen  rays — visible  to  the  eye  (see  p.  54). 

Tests  for  Platinum  Salts.— With  hydrogen  sulphid  plati- 
num solutions  yield  a  dark  brown  precipitate,  insoluble  in  hydro- 
chloric acid.  With  potassium  or  ammonium  hydroxid  and  excess 
of  hydrochloric  acid  a  yellow  precipitate  results. 


CERIUM — URANIUM  361 

CERIUM 

Symbol,  Ce.     Atomic  weight,  140. 

Cerium  is  a  rare  metal  of  the  family  of  alkaline  earths.  It 
forms  two  series  of  salts:  cerous,  containing  tricerion,  Ce"";  and 
eerie,  containing  tetracerion,  Ce"".  In  the  arts  it  is  of  some 
importance  because  its  oxid,  CeO2,  is  added  in  small  amounts  to 
thoria  to  make  the  brilliant  white  mantles  of  incandescent  gas 
lights. 

Cerii  OXalas  (Ce2(C2O4)3 .  9H2O)  (cerium  oxalate)  is  a  white 
powder,  tasteless  and  odorless,  insoluble  in  water  or  alcohol. 
It  is  used  in  obstinate  vomiting  in  the  form  of  a  pill.  Dose: 
i  to  5  gr.  (0.06-0.66  gm.). 

THORIUM 

Symbol,  Th.     Atomic  weight,  232.5. 

This  metal  is  a  constituent  of  very  rare  minerals,  notably  of 
monazite  sand.  Its  oxid,  thoria,  ThO2,  is  a  white  powder  which 
is  left  as  a  coherent  mantle  on  firing  the  cotton  netting  of  a  Welsbach 
light  saturated  with  the  nitrate.  An  addition  of  about  i  per  cent, 
of  cerium  oxid  is  necessary  for  the  most  perfect  light.  This  metal 
shares  with  uranium  and  radium  radio-active  powers,  sending  out 
through  opaque  envelops  rays  which  light  up  phosphorescent 
substances.  These  rays  influence  photograph  plates  and  dis- 
charge electrified  bodies  (see  p.  248). 

URANIUM 

Symbol,  U.     Atomic  weight,  239.5. 

This  metal  is  rare  and  of  difficult  fusibility,  having  no  technical 
use  in  the  pure  state.  It  forms  compounds  that  appear  to  be 
stages  in  a  series  in  which  it  is  first  trivalent  and  last  octavalent. 
Beside  these  it  forms  cations,  such  as  U(OH)4"  and  UO2",  con- 
tained in  the  salts  of  uranyl.  Uranium  glass  is  a  bright  yellow 
with  a  brilliant  green  fluorescence.  The  mineral  pitchblende  has 
grown  famous  as  the  chief  source  of  radium.  It  is  a  black  sub- 
stance, composed  mainly  of  uranous  uranate,  U(UO4)2. 

This  mineral  or  any  salt  of  uranium  has  the  power  of  acting 
through  an  opaque  cover  upon  a  photograph  plate,  just  as  if 
light  had  shone  on  it  exposed.  These  emissions  conduct  away 
the  charge  of  an  electrometer,  and  make  luminous  a  screen  of 
barium  platinocyanid.  Like  radium,  it  appears  to  be  an  inex- 
haustible source  of  radiant  energy — chemical,  electric,  and  optic 
(see  p.  248). 


362  THE    METALS 

MOLYBDENUM 

Symbol,  Mo.     Atomic  weight,  96. 

This  is  a  metal  like  uranium,  with  a  variety  of  compounds  and 
with  a  valency  ranging  from  II.  to  VI.  By  roasting  its  native 
sulphid,  MoS2,  the  oxid  is  formed. 

Molybdenum  trioxid,  MoO3,  is  the  anhydrid  of  a  series  of 
acids,  varying  in  the  proportions  of  water.  The  trioxid  unites 
with  other  acids  to  form  more  complex  acids,  as  phosphomolybdic 
acid,  H3PO4 .  i2MoO3,  which  is  a  reagent  for  precipitating  alkaloids. 

Ammonium  molybdate  dissolved  in  nitric  acid  gives  molyb- 
dic  acid,  H2MoO4,  which  is  used  to  precipitate  phosphoric  acid 
as  a  yellow  powder,  the  ammonium  salt  of  the  above  acid.  This 
precipitate  is  insoluble  in  acids,  but  soluble  in  ammonium  hy- 
droxid.  From  this  ammoniacal  solution  magnesia  mixture  pre- 
cipitates ammonium-magnesium  phosphate. 


ORGANIC    CHEMISTRY  363 


ORGANIC  AND  PHYSIOLOGIC  CHEMISTRY 

Organic  chemistry  deals  with  the  products  peculiar  to  organ- 
ized bodies.  These  products  are  not  found  in  nature,  except 
in  living  organisms.  The  most  characteristic  of  them  have  been 
made  by  synthesis  in  the  laboratory,  and  thus  it  has  been 
established  that  the  same  chemical  forces  are  concerned  in  the  pro- 
duction of  both  organic  and  inorganic  substances.  All  of  them 
are  carbon  compounds  in  which  the  carbon  is  combustible.  As 
carbonates  do  not  burn,  they  are  considered  to  be  inorganic.  Some 
organic  compounds  exist  in  plants  ready-made,  like  sugar,  starch, 
and  medicinal  alkaloids;  some,  like  urea,  albumin,  and  oils,  are 
found  in  animals.  Many  are  derived  from  petroleum,  or,  like  the 
anilin  products  and  carbolic  acid,  are  made  from  coal-tar;  or,  like 
creosote  and  wood  spirits,  result  from  the  distillation  of  wood. 
Fermentations  of  different  kinds  produce  alcohol  and  acetic  acid, 
which,  in  turn,  yield  many  derivatives. 

Organic  analysis  may  be  of  different  degrees  of  refinement. 
Proximate  analysis  may  be  simply  the  determination  of  water  and 
solids  by  evaporation  to  dryness  in  a  water-bath,  and  weighing 
the  residue.  The  presence  of  carbon  is  detected  by  ignition  in  a 
crucible,  the  residue  swelling  up,  blackening,  and  taking  fire, 
leaving  an  incombustible  whitish  remainder.  The  part  that  burns 
is  said  to  be  organic,  the  remainder  is  stated  as  ash. 

A  finer  division  is  obtained  from  the  solid  residue  by  washing 
out  the  fats  with  ether,  the  extractives  with  hot  alcohol,  and  the 
soluble  minerals  with  hot  water,  leaving  the  proteins  and  insoluble 
minerals.  The  proteins  may  be  separated  into  the  various  albu- 
mins,— the  fats  into  saponifiable  and  non-saponifiable,  and  the 
minerals  into  different  metallic  salts. 

Ultimate  analysis  is  performed  by  breaking  down  the  com- 
pound into  simpler  combustion  products  with  the  heat  of  a  Bunsen 
burner.  Qualitative  results  are  obtained  by  the  following  pro- 
cedures: 

Experiment  i. — Into  a  small  dry  test-tube  put  a  piece  of  starch. 
Heat  to  redness  while  holding  the  tube  horizontally.  The  starch 
swells  and  blackens  and  drops  of  water  appear  on  the  cool  part  of 
the  tube.  The  water  proves  the  presence  of  hydrogen,  the  charring 
proves  that  carbon  is  probably  present.  To  make  sure  of  the 
carbon  it  must  be  burned  in  a  current  of  air  and  the  product  of 
combustion  passed  into  lime-water.  A  white  precipitate  is  char- 
acteristic of  carbon  dioxid  (p.  103). 


364  ORGANIC    CHEMISTRY 

Experiment  2. — We  can  detect  nitrogen  by  causing  it  to  com- 
bine with  hydrogen  as  ammonia,  NH3,  which  is  easily  identified 
by  its  odor  and  alkalinity.  Into  a  small  dry  test-tube  put  some 
pieces  of  cheese,  glue,  quill,  wool,  or  hair  with  soda-lime.  A  strip 
of  moist  red  litmus-paper  is  held  in  the  upper  part  of  the  tube, 
which  is  heated  in  a  horizontal  position.  There  is  a  disagreeable 
smell,  the  smoke  turns  the  red  paper  blue,  a  dew  is  seen  on  the 
glass,  and  a  charred  residue  in  the  bottom  of  the  tube. 

Experiment  3. — A  nitrogenous  organic  substance  ignited  with 
sodium  produces  sodium  cyanid,  NaCN.  Into  a  small  dry  test- 
tube  put  a  small  quantity  of  uric  acid.  Upon  it  place  a  piece  of 
sodium,  twice  the  size,  and  heat  in  a  Bunsen  flame  until  charring 
occurs  and  other  action  ceases.  While  still  hot  the  tube  is  stirred 
about  in  a  test-glass  of  water,  so  that  the  tube  breaks  and  its  con- 
tents dissolve.  The  black  matter  may  be  allowed  to  settle  or  it 
may  be  filtered  out,  and  the  clear  portion  be  tested  for  sodium 
cyanid  by  the  Prussian-blue  test.  Add  a  few  drops  of  fresh  ferrous 


FIG.  71. — Estimation  of  carbon  and  hydrogen  by  combustion  of  organic  substance:  a  to  b,  Com- 
bustion tube;  e,  e,  asbestos  plugs;  /  to  /,  copper  oxid;  n,  glass  bulb  for  volatile  liquid;  d,  platinum 
boat  containing  substance  analyzed;  /,  drying  tube  containing  calcium  chlorid;  m,  potash  bulbs;  g, 
h,  j,  apparatus  for  ridding  air  of  its  moisture  and  carbon  dioxid;  &,  furnace  of  gas  burners. 

sulphate,  the  same  quantity  of  ferric  chlorid,  and  enough  hydro- 
chloric acid  to  change  the  brown  precipitate  to  a  blue  solution  of 
ferrous  ferrocyanid. 

Ultimate  analysis  reveals  how  few  are  the  elements  that  enter 
into  the  composition  of  the  great  number  of  organic  bodies.  Of 
these  few  elements  cyanogen  contains:  C  and  N;  the  hydrocar- 
bons C  and  H;  the  fats  and  carbohydrates  have  C,  H,  and  O; 
the  alkaloids  C,  H,  O,  and  N;  albumin  has  C,  H,  O,  N,  and  S; 
nerve  matter  C,  H,  O,  N,  S,  and  P;  hemoglobin  C,  H,  O,  N,  S, 
and  Fe. 

The  substance  to  be  analyzed  is  placed  (Fig.  71)  with  an  oxy- 
gen-yielding compound,  CuO  (/  to  /),  iiTa  hard  glass  tube  (a  to  b) 
plugged  loosely  with  asbestos  (e,  e).  The  tube  is  then  heated  in 
a  furnace  (&),  while  a  stream  of  oxygen,  dried  in  the  towers  of 
calcium  chlorid  or  sulphuric  acid  (h,  ;),  carries  the  combustion  to 
the  point  of  complete  oxidation.  The  carbon  is  converted  into 


ULTIMATE    ANALYSIS  365 

CO2,  which  is  caught  in  the  absorption  bulbs  (m)  containing  KHO; 
the  hydrogen  changes  to  H2O,  which  is  absorbed  in  passing  through 
the  tube  (/)  holding  CaCl2.  The  increase  of  weight  in  the  absorp- 
tion bulbs  and  drying  tube  stands  for  the  carbon  dioxid  and  water 
resulting  from  the  combustion.  The  molecular  weight  of  CO2  is 
44,  and  for  every  44  (n)  parts,  12  (3)  are  carbon.  The  molecular 
weight  of  water  is  18,  and  for  every  18  (9)  parts  2  (i)  are  hydrogen. 
The  difference  between  the  sum  of  the  weights  and  the  weight  of  the 
body  analyzed  represents  the  oxygen  which  was  not  collected. 

Example. — Let   us   suppose   the   analysis   to   be   of  a   piece   of 
sugar  weighing  0.09005  gm.     On  combustion  it  forms  0.0539  gm. 


FIG.  72. — Nitrogen  estimated  as  ammonia:  a,  Asbestos  wad;  a  to  b,  soda-lime;  b  to  c,  substance 
tested  and  soda-lime;  c  to  d,  soda-lime;  d,  asbestos  plug;  e,  absorption  bulb  containing  hydrochloric 
acid. 

of  H2O  and  0.19005  gm.  of  CO2.  As  i  of  H2O  is  hydrogen,  the 
sugar  contains  o. 0539  Xi  =  o. 00599  gm.  of  H.  As  -fo  of  CO2  is 
carbon,  the  sugar  contains  0.19005  X ^  =  0.03819  of  C.  Therefore, 

100X0.00599 

100  gm.  of  sugar  contains—         =°-°5  gm-  oi  hydrogen, 

0.09005 

100X0.03819 

and •  =  42.41  gm.  of  carbon.    The  remainder  is  oxygen. 

0.09005 

r  0  =  42.41 

Then,  to  state  percentage :<  H=   6.65; 

(0  =  50.94. 

Nitrogen  Content. — If  there  be  reason  to  believe  that  nitrogen 
is  present,  then  heating  in  a  furnace  with  soda-lime  (Fig.  72,  a  to 
b  and  c  to  d)  gives  the  N  as  NH3  gas.  This  ammonia  is  caught 
by  passing  into  HC1  contained  in  a  suitable  tube  (e}t  where  it  is 
fixed  as  NH4C1.  The  NH4C1  is  precipitated  with  platinum  chlorid, 
weighed,  and  the  calculation  made  on  the  basis  of  the  molecular 
weight  of  NH4  as  18,  and  nitrogen,  14. 

KjeldahVs  process  for  estimating  nitrogen  is  a  standard  method 
suitable  for  organic  solids  or  liquids:  (i)  By  heating  with  strong 
sulphuric  acid  the  nitrogen  is  converted  to  ammonium  sulphate. 
(2)  Next  this  acid  solution  is  decomposed  by  heating  with  excess 
of  sodium  hydroxid.  The  ammonia  gas  evolves  and  is  received 
in  an  absorbing  fluid  which  is  a  known  volume  of  standard  acid. 
The  diminution  of  acidity  is  finally  determined  volumetrically. 


366 


ORGANIC    CHEMISTRY 


(1)  Thus,  in  testing  urine  5  c.c.  are  treated  in  a  round-bottomed 
digesting  flask  of  250  c.c.  capacity  with  a  pinch  of  yellow  mer- 
curic oxid  (0.3  gm.)  to  assist  oxidation  and  20  c.c.  of  pure  strong 
sulphuric  acid.     To  prevent  loss  from  spurting,  a  piece  of  paraffin 
about  the  size  of  a  pea  is  added  and  the  flask  sloped  over  a  small 
flame  until  the  mixture  boils.     At  first  it  blackens.     In  twenty 
minutes  10  gm.  of  ignited  potassium  sulphate  in  powder  is  added 
to  raise  the   boiling-point   and  the   gentle   boiling   continued  for 
another  forty-five  minutes,  by  which  time  the  black  color  is  dis- 
charged.    All  the  nitrogen  in  the  urine  is  now  dissolved  as  am- 
monium sulphate. 

(2)  The  cooled  acid  solution  is  washed  into  a  liter  flask  (a)  for 
decomposition  and  diluted  to  a  volume  of  300  c.c.     Ten  pieces  of 

granulated  zinc  are  added  to  prevent  bump- 
ing and  a  bit  of  paraffin  to  check  frothing; 
about  i  gm.  of  sodium  thiosulphate  is  added 
to  liberate  nitrogen  from  mercuric  oxid. 
Sodium  hydroxid,  40  per  cent.,  in  excess  is 
run  in  from  the  tap  funnel  (6),  which  is 
drawn  out  to  a  fine  point  below.  On  heat- 
ing, the  ammonia  distils  into  the  absorp- 
tion flask  (h)  which  contains  a  measured 
amount  (about  30  c.c.)  of  one-fifth  normal 
sulphuric  acid.  This  acid  has  a  few  drops 
of  methyl-orange  in  it  and  was  poured  into 
flask  h  through  the  absorption  tube  (n)  so 
as  to  leave  the  broken  glass  in  it,  wet  with 
the  dilute  acid,  to  catch  any  traces  of 
ammonia  which  may  escape  the  acid  in 
flask  (h).  The  ammonia  enters  the  flask 
(h)  by  way  of  a  5o-c.c.  pipet  which  dips 
just  below  the  surface  of  the  acid  and  by 
its  enlargement  (d)  receives  any  of  the  acid 
sucked  back  from  flask  (h)  and  prevents 
its  entering  flask  (a).  As  soon  as  all  the 

NaHO  solution  has  dripped  slowly  in,  the  cock  is  closed  and  the 
mixture  is  boiled  about  a  half  hour,  when  about  two-thirds  have 
passed  over.  The  methyl-orange  must  not  change  to  yellow,  which 
would  indicate  that  the  acid  in  (h)  had  not  been  sufficient.  The 
evolution  of  ammonia  being  completed,  the  absorption  tube  (n) 
is  washed  with  water  and  the  acid  made  up  with  water  to  200  c.c. 
It  is  then  transferred  to  a  beaker  and  titrated  with  one-fifth  normal 
sodium  hydroxid  in  a  buret.  Example:  Suppose  it  is  found  that 
the  neutral  point  is  reached  when  20  c.c.  of  the  equivalent  soda 
solution  have  been  added.  Then  30  c.c.  —  20  c.c. 


FIG.  73. — Kjeldahl  process, 
apparatus  for  decomposition  of 
ammonium  sulphate. 


10  c.c.,  which 


MOLECULAR    FORMULA  367 

represents  the  amount  of  acid  consumed  in  absorbing  the  ammonia. 
As  i  c.c.  of  one-fifth  normal  H2SO4  corresponds  to  0.0028092  gm. 
of  nitrogen  this  balance  of  10  c.c.  contains  0.0028092X10  = 
0.028092  of  N.  As  5  c.c.  of  urine  yields  this  0.028092,  100  c.c. 
would  yield  20  X  0.028092  =  0.561840  gm.  percentage  of  nitrogen. 

Phosphorus  and  Sulphur  Content.  —  Having  removed  the 
carbon  and  hydrogen  by  oxidation,  the  residue  containing  sulphur 
and  phosphorus  is  completely  oxidized  by  fusing  a  known  quantity 
with  a  mixture  of  potassium  nitrate  and  sodium  carbonate.  The 
P  is  oxidized  to  P2O5,  which  is  determined  by  solution  and  pre- 
cipitation with  magnesia  mixture.  The  S  is  oxidized  to  SO4, 
which  is  determined  by  solution  and  precipitation  with  BaCl2. 

Empiric  Formula.  —  When  it  is  desired  to  determine  the 
formula  of  an  organic  substance,  we  first  analyze  it  by  the  com- 
bustion process  and  calculate  the  percentage  of  the  constituents. 
The  percentage  divided  by  the  atomic  weight  gives  the  propor- 
tional number  of  atoms,  which  proportion  can  be  simplified  by 
dividing  each  term  with  a  common  factor  which  in  the  case  below 

is  3-33- 

Example.  —  A  sample  of  acetic  acid  on  combustion  yielded  carbon, 
39.95  per  cent.;  hydrogen,  6.69  per  cent.  Then  the  remainder  was 
oxygen,  53.36  per  cent. 

C  =  -       -  =  3.33       or       i  as  lowest  ratio; 

6.60 
H  =  -  -  =  6.69       or       2 


O  -  =  3-33       or       i 

Molecular  Formula.—  The  simplest  expression  of  the  ratio 
of  its  elements  being  i  :  2  :  i,  the  empiric  formula  of  acetic  acid 
would  be  CH2O.  But  formaldehyd,  CH2O,  acetic  acid,  C2H4O2, 
and  lactic  acid,  C3H6O3,  all  have  the  same  percentage  composition, 
and  the  same  empiric  formula.  The  formula  found  most  useful 
is  one  which  tells  the  total  number  of  atoms  in  the  molecule. 
This  molecular  formula  may  not  express  the  lowest  ratio,  but  a 
multiple  of  it.  There  are  several  methods  of  deducing  it,  one  of 
these  depending  on  the  determination  of  the  vapor  density. 

The  law  is  that  the  molecular  weight  is  equal  to  twice  the  vapor 
density  (H=i)*or  to  the  specific  gravity  of  its  vapor  (air=i)  mul- 
tiplied by  28.88.  The  density  of  the  vapor  of  acetic  acid  is  30 
times  that  of  hydrogen;  therefore,  its  molecular  weight  is  30X2  = 
60.  But  the  formula  CH2O  sums  up  to  a  molecular  weight  of  30; 
to  make  it  60  we  must  double  the  atoms  and  write  it  C2H4O2. 


368  ORGANIC    CHEMISTRY 

As  acetic  acid  is  an  organic  acid,  the  analysis  of  one  of  its  salts 
is  of  value.  For  this  purpose  the  salt  of  silver  is  preferred,  a 
weighed  quantity  of  which  ignited  in  a  porcelain  crucible  gives 
a  residue  of  pure  silver.  Experiment  shows  that  there  is  but  i 
compound  of  silver  with  acetic  acid,  i  atom  of  hydrogen  being 
replaced  by  i  of  silver.  As  100  parts  of  silver  acetate  leave  a 
residue  of  64.68  parts  by  weight  of  silver,  the  vanished  portion 
was  35.32  parts  of  the  C,  H,  and  O.  The  atomic  weight  of 

35.32  X  107.66 

silver  is   107.66;  therefore, 7 — -^ =58.8.      In  the  salt   i 

O4«oo 

atom  of  hydrogen  of  the  acid  was  replaced  by  i  of  silver  and 
must  be  restored  to  get  the  true  molecular  weight:  58.8+1  = 
59.86;  in  round  number  60.  Its  formula  would  therefore  be — 

C2       =       24 

H4        =          4 

02       =       32 

60 

The  cryoscopic  method  for  determining  molecular  weight  is 
serviceable  for  substances  which  cannot  be  vaporized  without  de- 
composition. A  solution  of  sugar  freezes  at  a  lower  temperature 
than  does  pure  water,  the  depression  of  the  freezing-point  of 
weak  solutions  being  directly  proportional  to  the  weight  of  sugar 
dissolved.  For  example,  to  dissolve  sugar,  i  part  in  100  of  water, 
is  to  depress  the  freezing-point  of  the  water  from  o°  C.  (32°  F.) 
to  —0.058°  C.  (31.8956°  F.);  a  2-per  cent,  solution  lowers  it  to 
-0.116°  C.  (31.7912°  F.);  3  per  cent.,  -0.174°  C.  (31.6868°  F.). 
On  testing  weak  solutions  of  various  organic  substances  in  other 
solvents,  such  as  acetic  acid,  benzene,  etc.,  it  is  found  that  the 
lowering  of  the  freezing-point  is  approximately  proportional  to 
the  number  of  molecules  of  the  dissolved  substance  in  a  given 
weight  of  the  solvent,  irrespective  of  the  nature  of  the  substance. 

Law  of  Raoult. — From  these  facts  Raoult  deduced  the  law 
that  solutions  in  a  given  quantity  of  the  same  solvent  of  the  molec- 
ular weight  in  grams  oj  different  substances  will  lower  the  freezing- 
point  to  the  same  degree.  That  is  to  say,  with  normal  solutions 
(gram  molecular)  in  a  given  solvent  the  freezing-point  lowering  is 
a  constant  quantity,  called  the  co-efficient  oj  molecular  depression 
and  indicated  by  K.  The  value  of  K  for  water  is  19;  for  acetic 
acid,  39;  for  benzene,  49. 

To  determine  the  molecular  weight  of  an  organic  substance 
dissolve  i  gm.  (P)  in  100  of  the  solvent,  and  observe  the  de- 
pression of  the  freezing-point  (D).  Then,  molecular  weight  = 

KXP 

— — —  The  observation  is  best  made  with  Beckmann's  appa- 
ratus, described  under  Cryoscopy  (p.  38). 


MOLECULAR    FORMULA 


369 


Example. — Cane-sugar,  5.139  gm.  (P),  dissolved  in  100  c.c.  of 
water,  lowered  the  freezing-point  0.295°  C.   (P)-     The  constant 

for  water  as  solvent  (K)  is  19;  then,  — - — '— —  =  331, 


0.295 


This  is 


very  near  the  theoretic  value,  342. 

The  Boiling-point  Method. — In  another  place  it  has  been 
stated  that  dissolved  substances  raise  the  boiling-point  of  a  solvent 
to  an  extent  corresponding  to  the 
depression  they  cause  in  the 
freezing-point.  In  both  cases 
the  effect  depends  upon  the 
ratio  between  the  number  of 
molecules  of  the  dissolved  sub- 
stance and  the  number  of  those 
of  the  solvent.  Observations 
must  first  be  made  to  fix  the 
boiling-point  constant  of  the 
solvent.  This  is  done  by  noting 
the  rise  of  boiling-point  (p)  of 
the  solvent  occasioned  by  dis- 
solving in  100  gm.  of  it,  the 
molecular  weight  in  grams  of 
any  non-electrolyte  or  undisso- 
ciated  solid.  The  apparatus  em- 
ployed is  described  below. 

Beckmann's  Method  for  Deter- 
mining the  Boiling-point. — The 
effect  produced  upon  the  boiling- 
point  of  a  fluid  by  dissolving  sub- 
stances in  it  is  determined  by  the 
apparatus  shown  in  Fig.  74.  The 
solution  to  be  studied  is  put  in 
the  glass  tube,  A,  so  as  to  cover 
the  bulb  of  the  thermometer. 
Below  the  bulb  (not  touching  it) 
and  at  the  bottom  of  this  tube 
are  glass  beads  which  promote 


FIG.  74. — Beckmann's  boUing-point  apparatus. 


ebullition  at    a    uniform    rate. 


Rising  from  the  boiling  tube  is  a  worm-like  condenser,  K,  for 
returning  the  vapor.  Surrounding  the  tube,  A,  is  a  double- 
walled  glass  jacket,  B,  containing  some  of  the  same  solution 
that  is  being  studied  in  A.  Connected  with  B  is  a  returning  con- 
denser, K2.  The  apparatus  stands  on  an  asbestos  box,  heated  by 
two  burners  below. 

First,  pure  water  or  any  other  solvent  to  be  used  is  put  in  A, 
with  the  beads,  and  boiled.     The  special  thermometer  is  inserted 
24 


370 


ORGANIC    CHEMISTRY 


and  adjusted  while  in  the  apparatus,  so  that  the  surface  of  the 
mercury  stands  between  o°  C.  (32°  F.)  and  i°  C.  (33.8°  F.),  after 
the  thermometer  has  been  gently  knocked.  Heat  is  withdrawn 
and  the  tubes  emptied,  cleaned,  and  dried.  Again  the  beads  are 
put  in  A  with  a  weighed  amount  of  the  pure  water  or  other  solvent. 
The  thermometer  is  again  put  in  place  and  the  condenser  inserted. 
The  glass  jacket  B  is  also  filled  with  the  solvent,  and  the 
contents  of  A  and  B  are  both  heated  to  boiling  for  twenty 
minutes.  A  record  is  made  of  the  reading  of  the  thermometer 
and  the  barometer.  Again  the  heat  is  withdrawn;  a  weighed 
quantity  of  the  substance,  the  molecular  weight  of  which  is  to  be 
determined,  is  dissolved  in  the  solvent  contained  in  A  and  B. 
The  lamps  are  now  applied  and  the  liquids  boiled,  the  tempera- 
ture is  taken  and  corrected  for  any  barometric  changes.  The 
record  made  by  the  pure  solvent  subtracted  from  that  of  the 
solution  gives  the  rise  due  to  the  substance  dissolved.  The  ele- 
vation is  proportionate  to  the  quantity  dissolved,  provided  the 
substance  is  not  volatile. 

pw 
The  molecular  weight  is  determined  by  the  formula  m  =  — ,  in 

which  w  =  gram- weight  of  the  substance  dissolved;  ^  =  the  boil- 
ing-point constant  of  the  solvent;  r  =  observed  rise  in  boiling- 
point;  5  =  gram-weight  of  the  solvent.  The  value  of  p  for  water 
is  5.1;  for  acetic  acid  25.3;  for  ether  21.6;  for  ethyl  alcohol  11.7. 

Effect  oj  Dissociation. — The  inorganic  electrolytes  (acids,  bases, 
and  salts)  show  greater  depression  of  the  freezing-point  and  ele- 
vation of  the  boiling-point  than  do  the  organic  non-electrolytes. 
The  lowering  and  the  rise  are  dependent  upon  the  number  of 
particles,  which  in  organic  solutions  is  limited  to  the  molecules 
dissolved.  The  quantities  increase  in  value  with  the  inorganic 
electrolytes,  because  their  molecules  are  partly  dissociated  into 
ions  which  add  to  the  number  of  particles  in  solution. 

Constitutional  or  Structural  Formula.— Experiment  with 
bases  shows  that  only  i  of  the  H  atoms  in  acetic  acid,  C2H4O2,  is 
replaceable  by  a  metal.  To  express  this  fact  i  atom  may  be  set 
apart  as  C2H3O2H.  When  acted  upon  by  phosphorus  terchlorid, 
i  atom  each  of  H  and  O  are  substituted  by  a  single  atom  of 
chlorin.  Then  to  represent  this  idea  of  the  constitution,  the  OH 
must  be  set  apart  as  in  this  equation: 

3C2H3O.OH      +      PC13      =      3C2H3OC1      +      P03H3. 

We  are  justly  entitled  to  assume  that  the  H  and  O  are  linked 
together  in  the  group  hydroxyl.  Other  experiments  give  sanction 
to  the  view  that  3  of  the  hydrogen  atoms  are  contained  in  a  methyl 


CLASSIFICATION    OF    CARBON    COMPOUNDS  371 

group,  CH3,  and  this  notion,  added  to  the  others,  is  usually  rep- 
resented in  the  constitutional  or  rational  formula,  CH3.COOH, 
which  is  read,  methyl  united  with  carboxyl. 

Classification  of  Carbon  Compounds.— The  starting-point 
for  the  study  of  organic  chemistry  is  the  compound  consisting  only 
of  carbon  and  hydrogen,  and  known  as  a  hydrocarbon.  The 
other  more  complex  substances  may  be  regarded  as  derived  from 
hydrocarbons  by  rearranging  the  atoms  in  the  molecule,  or  by 
substituting  for  the  hydrogen  atoms  other  elements  or  groups 
of  elements  known  as  radicals.  These  changes  are  accomplished 
by  the  agencies  referred  to  under  Inorganic  Chemistry,  such  as 
heat,  oxidation,  reduction,  the  energetic  action  of  the  halogens, 
nitric  acid,  and  caustic  alkalis;  and  by  processes  called  organic, 
such  as  the  fermentations  and  putrefactions. 

The  number  of  substances  to  be  grouped  for  study  is  enor- 
mous and  their  classification  by  no  means  easy.  One  system, 
not  perfect,  but  which  is  generally  adopted  and  has  the  merit  of 
simplicity,  is  based  upon  the  assumption  that  all  organic  sub- 
stances with  constitutions  that  have  been  worked  out  are  deriv- 
atives of  one  of  two  hydrocarbons,  methane,  CH4,  or  benzene, 
C6H6.  The  two  great  classes  are  (i)  those  closely  related  to 
methane,  called  paraffins,  aliphatic  or  fatty  compounds,  and  (2) 
those  allied  to  benzene,  called  the  coal-tar,  cyclic,  or  aromatic 
compounds.  In  the  paraffins  the  carbon  atoms  are  linked  in  an 
open  or  arborescent  chain.  The  aromatic  compounds  contain  one 
or  more  closed  chains  or  rings. 


-U- 

|      I  -C     C- 

Open  chain.  \-^ 

I 
Closed  chain. 

In   both   classes   are   found   compounds,   the   nature   of   which 
is  indicated  in  the  following  summary: 

(1)  Hydrocarbons    containing    only    hydrogen    and    carbon,    as 
marsh  gas,  CH4. 

(2)  Halogen  derivatives,  or  halids,  in  which  one  or  more  halogen 
atoms  are  substituted  for  the  hydrogen  of  a  hydrocarbon,  as  methyl 
chlorid,  CH3C1. 

(3)  Alcohols,  the  hydroxids  of  hydrocarbon  radicals,  as  ethyl 
alcohol,   C2H5OH. 

(4)  Aldehyds,   compounds   of   a   hydrocarbon   radical   and  the 
group  COH;  for  example,  acetic  aldehyd,  CH3 .  COH. 


372  ALIPHATIC    COMPOUNDS 

(5)  Acids,    compounds    in    which    hydrocarbon    radicals    are 
united  to  carboxyl,  COOH,  as  acetic  acid,  CH3 .  COOH. 

(6)  Ethers,    combinations    of    two    hydrocarbon    radicals    with 
oxygen,  as  ethyl  ether,  (C2H5)2O  or  (C2H5)  .  O  .  (C2H5). 

(7)  Compound  ethers  or  esters,  compounds  formed  like  mineral 
salts  by  replacing  the  hydroxyl  in  an  alcohol  with  an  acid  radical: 

C2H5OH     +     CH3C02H     =     C2H5CH3C02     +     H2O. 

Ethyl  alcohol.  Acetic  acid.  Acetic  ether. 

(8)  Ketones,  compounds  of  two  hydrocarbon  radicals  with  car- 
bonyl,  as  dimethyl-ketone  or  acetone,  CH3 .  CO  .  CH3. 

(9)  Derivatives  not  classified  in  the  above  summary,  such  as: 
Carbohydrates,  originally  so  called  because  they  contain  carbon 

joined  to  hydrogen  and  oxygen,  which  are  combined  in  the  same 
ratio  as  in  water,  thus:  glucose  is  C6H12O6.  They  are  regarded  as 
being  aldehyd  alcohols  or  ketone  alcohols,  as  when  glucose  is 
written  CH2OH(CHOH)4COH. 

Amins  and  amids,  compounds  in  which  the  hydrogen  of  am- 
monia, NH3,  has  been  replaced  by  basic  and  acid  radicals  respec- 
tively, as  ethylamin,  NH2C2H5,  and  acetamid,  NH2C2H3O. 

Proteins,  compounds  of  carbon,  hydrogen,  oxygen,  nitrogen, 
sulphur,  and  sometimes  phosphorus  or  iron.  They  are  complex 
and  indefinite  in  structure,  as  albumin,  fibrin,  and  casein. 


ALIPHATIC  COMPOUNDS 

Methane  (CH4)  (Marsh  Gas).—  This  is  the  simplest  member 
of  a  numerous  series.  Its  common  name,  marsh  gas,  is  due  to 
its  occurrence  in  the  gases  which  bubble  up  on  stirring  the  decay- 
ing vegetable  matter  at  the  bottom  of  stagnant  pools.  Another 
name,  fire-damp,  is  given  it  by  coal  miners  who  encounter  it 
escaping  from  fissures  in  the  coal  veins.  It  is  the  chief  component 
of  the  natural  gas  of  petroleum  districts  of  Pennsylvania,  Ohio, 
and  Indiana,  and  of  the  illuminating  gas  manufactured  by  the 
distillation  of  bituminous  coal.  It  is  formed  when  steam  with 
vapor  of  carbon  bisulphid  is  passed  over  heated  copper: 

CS2  +   2H2O   +  6Cu  =    CH4   +    2Cu2S   +    2CuO. 

This  is  an  illustration  of  synthesis  or  building  up  of  an  organic 
compound  from  the  elements,  as  CS2  and  H2O  are  easily  made 
from  carbon,  sulphur,  hydrogen,  and  oxygen. 


METHANE  373 

Methane  is  prepared  by  heating  in  a  hard  glass  tube  i  part  of 
anhydrous  sodium  acetate  with  4  parts  of  soda  lime. 

CH3CO2Na      +      NaOH      =      CH4      +      Na2CO3 

Sodium  acetate.  Sodium  hydroxid.  Sodium  carbonate. 

In  this  reaction  acetic  acid  is  broken  up,  as  most  carbon  acids 
are,  by  heat,  yielding  a  hydrocarbon  and  a  carbonate. 

Experiment. — The  sodium  acetate  is  first  made  anhydrous  by 
heating  it  in  a  porcelain  capsule  until  it  fuses  to  a  brown  liquid. 
It  must  be  stirred  to  prevent  spurting.  The  cooled  residue  is 
ground  with  the  soda-lime  and  introduced  into  a  test-tube.  The 
tube,  fitted  with  a  delivery  tube  by  a  cork,  is  held  horizontally 
while  being  heated.  The  burner  is  kept  moving  to  prevent  melt- 
ing the  glass  tube.  The  gas  is  collected  over  water  in  other 
tubes.  If  a  tubeful  inverted  is  closed  with  the  thumb  and  held 
mouth  down,  the  gas  stays  in  the  tube  and  may  be  tested  with  a 
taper  as  hydrogen  is  sometimes  tested.  The  gas  burns  at  the 
mouth;  the  taper  goes  out  as  it  is  passed  up  inside  the  tube  (PL  i). 

Properties. — It  is  a  colorless,  odorless  gas,  slightly  soluble  in 
water,  over  which,  however,  it  can  be  collected.  It  does  not  sup- 
port combustion,  and  causes  suffocation  when  breathed.  It  burns 
with  a  non-luminous  flame,  and  mixed  in  the  properties  of  1-5 
with  air  forms  a  highly  explosive  mixture.  Accidents  in  coal 
mines  are  frequent  from  the  fire-damp.  Before  the  mixture  in  air 
reaches  the  explosive  ratio  the  presence  of  the  gas  is  detected  by 
the  blue  flame  or  corpse  light  inside  the  miner's  safety  lamp  (p.  103). 

CH4         +         202  C02         +         2H20 

2  volumes          +          4  volumes  =          2  volumes  +  4  volumes. 

A  very  marked  trait  is  its  stability,  being  unaffected  by  some 
of  the  most  energetic  chemical  agents.  It  is  equally  unaffected 
and  undissolved  when  passed  through  bromin  in  the  dark,  the 
caustic  alkalis,  strong  acids,  and  the  oxidizers,  potassium  per- 
manganate and  chromic  acid.  Other  hydrocarbons  of  the  same 
class  resist  reagents  in  the  same  way,  having  feeble  chemical 
energies;  hence  they  are  called  paraffins — slight  affinity. 

To  express  the  constitution  of  methane  and  the  valency  of 
each  atom  in  its  molecule,  the  following  diagram  is  used,  based 
upon  the  tetravalence  of  carbon  and  the  univalence  of  hydrogen: 

H 
H— C— H 


374  ALIPHATIC    COMPOUNDS 

Ethane,  C2H6,  is  a  constituent  of  the  natural  gas  of  petroleum 
districts,  and  is  dissolved  in  the  crude  petroleum.  It  is  produced 
when  methyl  iodid  is  treated  with  sodium  in  a  neutral  medium: 


2CH3I        +        2Na  C2H6        +         2NaI. 

Methyl  iodid.  Ethane. 

To  show  that  ethane  may  be  regarded  as  containing  two  methyl 
groups,  this  reaction  is  written  — 

=        2NaI        + 


This  reaction  illustrates  a  very  common  method  of  building  a 
more  complex  compound  from  simpler  parts.  It  has  been  shown 
how  methane  is  formed  by  synthesis  from  its  elements.  Methane 
treated  with  a  halogen,  such  as  chlorin  or  iodin,  forms  methyl 
chlorid  or  iodid,  which  is  one  step  toward  the  next  highest  hydro- 
carbon, ethane.  The  final  step  is  to  remove  the  halogen  by  its 
affinity  for  a  metal,  thus  permitting  the  residues  to  unite.  A 
similar  process  enables  us  to  pass  on  to  higher  members  of  the 
same  series. 

Experiment.  —  Fill  a  voltameter  with  a  saturated  solution  of 
potassium  acetate  (CH3CO2)'K*,  containing  some  potassium 
hydroxid  for  absorption  of  CO2.  The  electric  current  causes  the 
cation  K  to  decompose  water,  liberating  hydrogen  at  the  negative 
pole,  while  at  the  positive  pole  acetanion  breaks  up  into  CO2, 
absorbed  by  the  potash,  and  CH3,  which  combines  with  another 
CH3  to  form  ethane,  C2H6. 


Properties.  —  Ethane  is  a  colorless,  tasteless  gas,  insoluble  in 
water.  It  burns  with  a  feebly  luminous  flame,  and  mixed  with  air 
in  the  right  proportions  is  explosive.  Like  methane,  it  is  very 
stable  even  when  in  contact  with  acids,  alkalis,  and  oxidizers. 

The  structure  of  ethane  is  indicated  in  the  graphic  formula  — 

H    H 

H—  C—  C—  H 

I       I 
H    H 

This  is  deduced  from  the  fact  that  univalent  hydrogen  cannot 
link  the  two  carbon  atoms,  but  carbon,  being  quadrivalent,  can 
join  the  other  carbon  atom  and  leave  six  points  for  the  six  hydrogen 
atoms. 


BUTANE  375 

Propane,  C3H8,  occurs  in  petroleum  and  can  be  made  by  treating 
ethyl  and  methyl  iodids  with  sodium: 

C2H5I      +      CH3I     +      2Na      =      C3H8     +      2NaI. 

Ethyl  iodid.  Methyl  iodid.  Sodium.  Propane. 

Properties. — At  common  temperatures  propane  is  a  gas,  but 
below  —17°  C.  (1.4°  F.)  it  condenses  to  a  colorless  liquid.  It 
burns  with  a  more  luminous  flame  than  either  ethane  or  methane, 
because  of  the  increased  proportion  of  carbon.  In  its  chemical 
properties  it  closely  resembles  the  other  two  hydrocarbons. 

From  the  reaction  given  above  it  is  concluded  that  propane  is 
formed  by  the  junction  of  the  ethyl  group  (C2H5)  to  the  methyl 
(CH3).  Thus: 

H    H  H 

I      I  I 

H— C— C—    joins  with    — C— H 

H    H  H 

which  would  give  it  the  constitution — 

H    H    H 

H-C-C-C-H 

f       I       I 
H    H    H 

This  may  be  written  CH3 .  CH2 .  CH3  or  CH3 .  C2H5. 

Butane,  hexane,  and  a  number  of  other  hydrocarbons  are  found 
in  petroleum,  all  having  chemical  properties  similar  to  those  of 
methane. 

Butane,  C4H10. — There  are  two  hydrocarbons  of  this  formula. 
The  one  occurring  in  petroleum  is  often  called  normal  butane. 
From  its  reactions  it  is  considered  to  be  diethyl,  and  may  be  writ- 
ten C2H5.C2H5,  or  CH3.  CH2.  CH2.  CH3;  the  graphic  formula 
being  written  thus: 

H    H    H    H 

I      I       I       I 
H— C— C— C— C— H 

till 
H    H    H    H 

The  other  butane,  called  isobutane,  does  not  occur  in  petro- 
leum, and  differs  from  the  normal  butane  by  being  produced  in 
different  reactions  and  having  different  physical  properties.  All 
these  hydrocarbons  are  alike  chemically,  but  this  is  without  doubt 
distinct  from  normal  butane,  though  its  molecular  formula  is  the 
same,  C4H10. 

A  study  of  its  methods  of  formation  and  chemical  behavior 
leads  to  the  conclusion  that  isobutane  has  the  constitution  CH 
(CH3)3,  or,  graphically  represented: 


376  ALIPHATIC    COMPOUNDS 


H  H 

H— C— H 


Isomerism. — The  two  butanes  are  called  isomeric  because 
with  the  same  molecular  formula  they  have  different  properties. 
They  are  said  to  be  isomers.  By  reference  to  the  graphic  formulas 
given  above  it  is  plain  that  isomerism  can  be  explained  by  a  differ- 
ence in  the  arrangement  of  the  atoms.  When  the  hydrocarbons 
are  represented  in  this  way  there  is  always  found  an  agreement 
between  the  number  of  isomers  and  the  number  of  different  dia- 
grams it  is  possible  to  construct  from  the  molecular  formula, 
assuming  carbon  to  be  tetravalent  and  the  carbon  atoms  to  have 
the  power  of  joining  to  other  carbon  atoms  to  make  a  skeleton  or 
open  chain.  As  the  number  of  carbon  atoms  increases  in  the 
hydrocarbons  heavier  than  butane,  the  number  of  possible  isomers 
increases  according  to  the  law  of  permutation.  There  are  three 
pentanes,  nine  heptanes,  seventy-five  decanes,  etc. 

It  has  been  shown  that  by  similar  processes  of  formation,  start- 
ing with  methane  and  substituting  CH3  for  one  atom  of  hydrogen, 
we  could  pass  to  ethane,  from  ethane  to  propane,  from  propane 
to  butane,  etc.  Theoretically,  there  is  no  limit  to  the  number  of 
hydrocarbons  that  can  be  thus  constructed,  and  as  a  matter  of 
fact  those  up  to  C40  and  over  are  known  and  have  been  separated 
from  petroleum.  For  these  reasons  it  is  convenient  to  class  them 
together  and  arrange  them  in  a  series  beginning  with  CH4,  and 
following  with  other  members  according  to  the  numbers  of  carbon 
atoms.  The  number  of  isomers  are  indicated  by  the  figures  in 
parentheses: 

SATURATED  HYDROCARBONS 
PARAFFINS    OR   METHANE   SERIES 

Methane    (i)   molecular  weight    1 6 CH4   . 

\  difference  CH, 
Ethane      (i)  "  "          30      ....  C2H6 


Propane     (i)  «  «          44     ....  C3H8 

1  «  CH2 
Butane  (2}  «  "  58-..  •  C4H10  * 

}  "  CH2 
Pentane  (3)  "  "  72  ....  C5H12^ 

1  «  CHt 
Hexane  (5)  «  »  86  ....  C6HU^ 

I  ««  CH, 
Heptane  (9)  "  «'  icx)  .  .  .  .  C7H16  j 


PARAFFINS  377 

Homologous  Series. — This  series  is  said  to  be  homologous, 
because  the  members  are  alike  in  constitution  and  chemical 
behavior;  because  with  increase  in  molecular  weight  there  is  a 
regular  and  gradual  progression  in  density,  boiling-point,  and 
other  physical  properties;  and  because  consecutive  members  dif- 
fer by  CH2.  The  corresponding  derivatives — alcohols,  ethers, 
acids,  etc. — may  likewise  be  arranged  in  well-marked  homologous 
series  of  similar  compounds,  differing  consecutively  by  CH2. 

General  Properties  of  Paraffins.— In  any  homologous  series 
the  composition  of  all  the  members  can  be  expressed  by  a  molec- 
ular formula  in  general  terms.  For  the  paraffins  the  general 
formula  is  CnH2n+2  ,  the  coefficient  n  standing  for  the  number  of 
carbon  atoms.  From  this  general  formula  the  molecular  com- 
position of  any  number  can  be  known.  For  example,  in  the 
fourth  member  the  value  of  n  must  be  4,  and  2^+2  =  10;  thus, 
C4H10. 

There  being  a  similarity  in  modes  of  production  and  chemical 
properties,  it  suffices  to  state  the  general  properties  of  a  series  as 
illustrated  in  a  few  members.  What  is  said  about  these  types 
will  apply  with  small  allowances  to  every  member  of  the  series. 
Hence,  a  detailed  account  of  each  is  unnecessary,  and  for  lack  of 
space  will  not  be  attempted  in  this  work.  To  know  the  behavior 
of  a  few  common  or  simple  members  is  to  have  a  basis  for  under- 
standing all  the  remainder. 

Nomenclature.— It  will  have  been  observed  that  all  the  names 
of  the  methane  series  terminate  in  ane.  From  and  including 
the  fifth  member  the  prefix  is  a  Greek  numeral  denoting  the 
number  of  carbon  atoms,  as  pent-ane,  hex-Sine,  dec-ane,  dodec-ane. 
On  removing  a  hydrogen  atom  there  is  left  a  residue  or  univalent 
radical  which  is  designated  by  changing  the  termination  ane 
to  yl,  as  meih-yl,  pent-^,  etc.  When  the  hydrogen  of  ethane, 
C2H6,  is  reduced  by  2  atoms  there  is  left  a  bivalent  radical  which 
changes  ane  to  ene,  as  C2H4  eth-ene',  reduced  by  3  atoms  it  leaves 
a  trivalent  radical,  changing  the  final  e  of  ene  to  yl,  as  C2H3  ethen-yl. 

The  derivatives  of  the  bivalent  radicals  are  denoted  by  the 
ending  ylene,  as  eth-ylene  chlorid,  C2H4C12  (p.  381). 

Physical  Properties  of  Paraffins.— At  ordinary  tempera- 
tures the  first  four  members  of  this  series  are  colorless  gases;  at 
lower  temperatures,  under  pressure,  they  condense  to  liquids,  with 
a"  readiness  proportionate  to  the  number  of  carbon  atoms.  The 
members  from  the  fourth  to  the  sixteenth  are  colorless  liquids 
with  boiling-points  and  molecular  weights  rising  together.  Above 
the  sixteenth  (C16H34)  the  hydrocarbons  are  colorless  solids,  the 
melting-point  rising  as  the  series  is  ascended.  They  are  all 
insoluble  in  water,  but  soluble  in  alcohol  and  ether. 


378  ALIPHATIC    COMPOUNDS 

Chemical  Properties  of  Paraffins.— They  are  all  satu- 
rated compounds  and  therefore  do  not  unite  directly  with  any 
element.  Their  most  marked  trait  is  stability,  resisting  equally 
well  strong  acids,  alkalis,  and  oxidizing  agents.  In  sunlight 
chlorin  and,  less  readily,  bromin  break  them  up,  substituting 
halogen  atoms  for  hydrogen. 

Petroleum  and  Natural  Gas. — These  are  the  chief  sources  of 
the  paraffins.  In  western  Pennsylvania  and  many  other  parts 
of  the  earth  a  gas  issues  from  the  earth  under  pressure,  sponta- 
neously or  when  wells  are  bored  to  certain  depths.  This  gas 
contains  hydrogen,  methane,  ethane,  propane,  and  other  gaseous 
hydrocarbons.  It  is  probably  the  product  of  the  decomposition 
of  remains  of  fish  and  other  sea  animals  deposited  with  certain 
geologic  strata. 

Another  natural  product  of  the  same  animal  destruction  in  the 
rocks  is  petroleum  or  rock  oil,  which  escapes  into  borings  from 
cavities  or  gravelly  strata  under  the  pressure  of  gaseous  con- 
stituents. 

Preparation. — Crude  petroleum  is  a  thick,  yellowish  or  brown 
liquid,  lighter  than  water,  which  is  freed  from  extraneous  organic 
matter  and  hydrocarbons  other  than  paraffins  by  treatment  with 
concentrated  sulphuric  acid.  The  acid  is  removed  and  the  residue 
of  oil  treated  with  alkali.  Thus  purified,  Pennsylvania  oil  is  com- 
posed almost  entirely  of  hydrocarbons  of  the  methane  series. 
This  crude  mixture  has  some  of  the  gaseous  members  dissolved 
in  it  which  make  it  too  inflammable  for  use  in  lamps.  To  get  the 
various  gaseous,  liquid,  and  solid  components  in  suitable  forms,  it 
is  necessary  to  separate  them  into  mixtures  of  different  boiling- 
points.  The  crude  oil  is  distilled  from  large  iron  boilers,  and  the 
vapors  condensed  into  receivers  which  are  regularly  changed  as 
the  temperature  is  made  to  rise  from  point  to  point. 

Fractional  Distillation. — The  saturated  hydrocarbons  are  not 
decomposed  by  boiling,  and  hence  may  be  separated  and  purified 
like  other  volatile  organic  substances  by  distilling  in  fractions. 
This  operation  is  performed  in  the  apparatus  shown  in  Fig.  75. 
The  organic  mixture  is  placed  in  the  flask  A,  which  has  a  per- 
forated stopper  carrying  a  thermometer,  the  bulb  of  which  comes 
just  below  the  side  opening,  B.  This  side  tube  connects  writh  a 
condenser  for  fluids  of  low  boiling-point,  but  when  the  tempera- 
ture must  be  raised  above  125°  C.  (257°  F.)  the  strain  of  hot 
vapor  upon  the  cold  tube  of  the  condenser  cracks  it.  In  such 
cases  connection  is  made  with  a  single  long  tube,  C,  without  an 
envelop  of  cold  water. 

On  applying  heat  the  more  volatile  constituents  boil  first  and 
are  condensed  into  a  receiver.  By  means  of  the  thermometer 


PETROLEUM  379 

the  temperature  can  be  noted  and  regulated.  With  the  same 
source  of  heat  the  temperature  of  an  organic  mixture  slowly  and 
continuously  rises,  and  the  portions  passing  over  at  different  inter- 
vals of  5°  or  10°  or  of  25°  C.  are  separated  by  being  received  in 
different  vessels. 

Treated  on  this  principle  petroleum  yields  the  commercial 
products  rhigolin,  b.-p.  21°  C.  (69.8°  F.);  petroleum  ether  or 
benzin,  b.-p.  5o°-6o°  C.  (i22°-i4o°  F.);  gasolin  or  naphtha,  b.-p. 
75°  C.  (167°  F.);  ligroin,  b.-p.  8o°-i2o°  C.  (i76°-248°  F.); 


FIG.  75. — Apparatus  for  distillation:    C,  Condenser  without  water  jacket  for  130°  C.;  B,  condenser 
with  water  jacket  for  lower  temperature. 

kerosene  or  astral  oil  for  illumination,  b.-p.  i5o°-25o°  C.  (300°- 
480°  F.);  paraffin  oil  or  mineral  oil,  b.-p.  25o°-3oo°  C.  (482°- 
572°  F.);  lubricating  oil,  b.-p.  above  300°  C.  (572°  F.).  The 
residue,  purified  by  boneblack,  is  the  soft  solid,  vaselin  or  petrolatum, 
melting  at  40°-5o°  C.  (io4°-i22°  F.);  and  at  a  higher  melting- 
point,  5o°-75°  C.  (i22°-i67°  F.),  paraffin  or  mineral  wax.  Fuel 
oil  is  a  cheap  product  not  used  for  illumination,  but  valuable  for 
heating  and  used  for  spraying  marshes  to  kill  mosquitoes. 

Flashing-point  of  Burning  Oils.— Owing  to  the  explosive 
mixtures  made  by  the  gases  escaping  from  the  lighter  products,  the 
laws  prohibit  the  sale  of  burning  oils  which  give  off  inflammable 


380  ALIPHATIC    COMPOUNDS 

vapor  at  temperatures  lower  than  the  standard,  usually  48°  C. 
(120°  F.).  Official  inspectors  test  the  oil  by  the  flashing  test,  the 
basis  of  which  consists  in  the  gradual  heating  of  the  oil,  in  which 
the  bulb  of  a  thermometer  is  immersed  so  as  to  determine  the 
point  at  which  a  flame  will  cause  a  flash  due  to  ignition  of  surface 
vapors. 

Toxicology. — Petroleum  and  its  products  are  all  somewhat 
poisonous,  the  gases  by  inhalation,  the  liquids  and  solids  by 
swallowing. 

Symptoms. — In  the  oil  refineries  and  in  rubber  factories  using 
benzin  as  a  solvent  for  rubber,  inhalation  causes  the  following 
symptoms:  general  debility,  palpitation  of  the  heart,  staring 
eyes,  hallucinations,  cough,  chronic  bronchitis.  Naphtha  drunk 
is  the  name  given  to  the  intoxication  it  produces.  This  is  some- 
times induced  purposely  by  inhaling  gasolin.  In  the  early  stage 
of  this  condition  the  victims  may  be  excited  and  in  high  spirits. 
These  symptoms  are  due  to  benzin;  but  the  asphyxia  is  due  to 
the  deficiency  of  oxygen.  Symptoms  of  intoxication  have  followed 
the  spilling  of  petroleum  in  a  tenanted  room.  In  very  severe 
cases — cardiac  weakness,  insensibility,  and  convulsions  may  be 
forerunners  of  death.  When  swallowed,  petroleum  is  a  local 
irritant  to  the  stomach,  causing  pain,  vomiting,  colic,  diarrhea,  etc. 
After  absorption  it  produces  headache,  dizziness,  rapid  pulse, 
labored  breathing,  cyanosis,  drowsiness,  collapse,  insensibility. 
Workers  in  petroleum  are  liable  to  boils  and  a  disseminated  acne, 
chiefly  on  the  arms  and  thighs. 

Fatal  Dose. — A  death  is  reported  from  J  oz.  of  benzin;  on  the 
other  hand,  recovery  has  followed  from  taking  i  pt.  of  petroleum. 
Fatal  cases  are  very  rare. 

Treatment. — The  stomach  should  be  evacuated  by  emetics  or 
by  hypodermic  injection  of  5  drops  of  a  2-per  cent,  solution  of 
apomorphin;  or  by  the  stomach-tube.  Purgatives  are  used  to 
empty  the  bowels.  For  the  collapse  hot  applications,  strychnin, 
and  other  cardiac  stimulants. 

Postmortem  appearances  show  no  characteristic  lesion.  The 
odor  of  petroleum  products  should  be  detected  in  the  contents  of 
the  stomach  and  bowels. 

Detection. — The  characteristic  odor  will  be  noticed  in  the  sus- 
pected material  and  in  the  vapors  obtained  by  fractional  distilla- 
tion. The  distillate  will  reveal  the  form  of  product  by  inflamma- 
bility, boiling-point,  etc. 


OLEFINS  381 

UNSATURATED  HYDROCARBONS 

OLEFIN    SERIES 
(The  possible  isomerids  shown  by  numbers  in  parentheses.) 

(i)  Ethene  or  Ethylene,       C2H4,  or  || 

CH2. 

CHCH3 
(i)  Propene  or  Propylene,   CgHe,  or 

CH2. 

CHCH2CHS 
(3)  Butene  or  Butylene,       C4H8,  or 

CH2. 

CH(CH2)2CH3 
(5)  Pentene  or  Amylene,      C5H10,  or 

CH2. 

The  action  of  chlorin  and  bromin  upon  the  paraffins  is  to  pro- 
duce substitution  products,  such  as  ethyl  bromid  and  chlorid.  By 
heating  these  with  alcoholic  solution  of  potassium  hydroxid  a 
new  sort  of  hydrocarbon  is  formed  by  the  loss  of  2  hydrogen  atoms: 

C2H5C1     +     KOH     =     C2H4     +     KC1     +     H2O. 

Ethyl  chlorid.  Ethene  or  ethylene. 

Any  higher  hydrocarbon  of  the  methane  series  will  substitute  i 
atom  of  hydrogen  for  chlorin,  and  then  with  the  alkali  yield  the 
corresponding  ethene  hydrocarbon. 

The  paraffin  with  2  carbon  atoms  is  ethane,  C2H6,  a  com- 
pletely saturated  compound;  but  ethene  has  2  atoms  less  of  hydro- 
gen, and  under  certain  circumstances  can  take  up  this  hydrogen 
again;  hence  it  is  called  unsaturated.  Arranged  with  other 
hydrocarbons  formed  by  a  similar  reaction,  there  is  made  a  homolo- 
gous series  of  the  general  formula,  C»H2W. 

Nomenclature. — The  termination  -ene  or  -ylene  is  substituted 
for  the  ane  of  the  corresponding  paraffin.  There  is  no  methene 
or  methylene,  ethene  being  the  simplest  member.  With  chlorin, 
ethylene  forms  an  oily  liquid,  ethylene  dichlorid;  hence  it  was 
called  oil  making  or  olefiant.  From  this  word  is  derived  the  name 
of  the  series  olefin. 

General  Properties.— Not  being  saturated,  the  members  of 
this  series  are  unlike  the  paraffins,  combining  directly  with  other 
compounds  or  elements,  and  forming  saturated  additive  products. 
The  reactions  of  these  hydrocarbons  leave  no  room  to  doubt  that 
their  form  of  unsaturation  is  properly  indicated  by  the  relation  of 

CH2 
the  carbon  atoms  in  the  structural  formula  for  C2H4,  as    || 

CH2. 


382  ALIPHATIC    COMPOUNDS 

The  first  four  of  the  series  are  gases;  the  fourteen  or  more 
above  these  are  liquids;  the  highest  members  are  solids,  showing 
an  elevation  in  melting-  and  boiling-points  as  we  pass  up  the 
series.  Insoluble  in  water,  they  dissolve  slightly  in  alcohol.  They 
burn  in  air  with  a  bright  but  smoky  flame.  Mixed  in  the  right 
proportion  with  air  they  can  be  exploded. 

Ethene  (ethylene,  defiant  gas)  occurs  as  a  colorless  constitu- 
ent of  illuminating  gas,  to  which  it  imparts  the  luminous  quality 
not  given  by  methane. 

Preparation. — Beside  the  mode  of  formation  (p.  381)  from 
ethyl  chlorid  and  potassium  hydroxid,  ethene  is  prepared  by 
destructive  distillation  of  coal  and  many  organic  substances. 
Compressed  in  cylinders,  it  furnishes  the  gas  used  in  the  Pintsch 
system.  By  direct  union  it  yields  the  halogen  derivatives,  ethyl- 
ene  chlorid,  C2H4C12;  ethylene  bromid,  C2H4Br2;  and  ethylene 
iodid,  C2H4I2. 

Propene  is  methyl  ethene,  C2H3-CH3. 

Butene  is  dimethyl  ethene,  C2H2(CH3)2;  or  ethyl  ethene, 
C2H3  —  C2H5. 

Pentene  (amylene)  has  been  produced  in  three  isomers,  only 
one  of  which  is  important.  This  is  called  pental,  iso-amylene, 
or  trimethyl-ethene,  C5H10  or  C2H(CH3)3.  It  is  prepared  by  dehy- 
drating amylene  hydrate  with  acids.  It  is  a  colorless  inflammable 
liquid.  Pental  is  used  in  medicine  as  an  anesthetic  in  doses  of  2 
or  3  fl.  dr.  (7.50-11.25  c.c.). 

ACETYLENE  SERIES 

C— H 

Ethine  or  Acetylene,  C2H2,  or  III 

C— H 

C— CH3 

Propine  or  Allylene,  C8H4  or  C2H.CH3     111 

C — H. 

General  Properties.— They  are  unsaturated  hydrocarbons  of 
the  general  formula  CnH2rt_2,  and  are  formed  by  treating  the 
halogen  monosubstitution  products  of  the  olefins  with  alcoholic 
potassium  hydroxid: 

C2H3Br     +     KOH     =     C2H2     +     KBr     +     H2O. 

Being  unsaturated,  they  can  unite  directly  with  4  atoms  of 
chlorin  or  bromin,  or  with  2  molecules  of  hydrochloric  acid, 
to  form  additive  compounds.  The  formula  of  acetylene  expres- 

CH 
sive  of  this  fact  has  this  structure:   HI  „ 

CH. 


ACETYLENE    SERIES  383 

Up  to  the  member  C12H22  they  are  gases  or  volatile  liquids  of 
a  characteristic  odor.  Sparingly  soluble  in  water,  readily  in  alco- 
hol, they  are  inflammable  with  a  luminous  but  smoky  flame. 

Acetylene  (C2H2)  (Ethine).-The  simplest  of  this  series  is 
acetylene,  a  constituent  of  coal-gas,  and  formed  when  the  vapor 
of  methane  or  coal-gas  is  passed  through  red-hot  tubes.  It  has 
four  atoms  of  hydrogen  less  than  ethane  C2H6.  In  the  following 
manner  it  is  a  step  in  the  synthesis  of  alcohol  from  its  elements: 

In  the  presence  of  hydrogen  the  arc  light  between  carbon 
electrodes  produces  it  by  a  simple  synthesis: 

C2       +        H2        =        C2H2. 

By  nascent  hydrogen  it  is  raised  to  C2H4,  ethylene,  and  this,  by 
the  action  of  sulphuric  acid  and  water,  produces  ethyl  alcohol, 
C2H5.OH.  ^ 

Preparation. — The  most  convenient  method,  and  the  one  used 
industrially,  is  that  consisting  in  the  treatment  of  calcium  carbid 
with  water.  A  gaseous  acetylene  is  evolved  and  calcium  hydroxid 
remains: 

C2Ca       +        2H20        =        C2H2       +        CaH202. 

Experiment. — If  a  piece  of  calcium  carbid  is  dropped  into  some 
water  in  a  capsule,  gas  bubbles  arise  which  take  fire  when  touched 
with  a  lighted  match. 

Properties. — Acetylene  is  a  colorless  gas,  odorless  when  pure, 
but  when  impure  has  an  odor  resembling  garlic.  Readily  soluble 
in  alcohol,  it  is  but  feebly  so  in  water.  It  liquefies  under  48 
atmospheres  of  pressure  at  o°  C.  (32°  F.).  It  burns  with  a  brilliant 
flame,  and  from  a  special  jet  it  gives  a  light  more  intense  than  that 
of  any  other  gas.  Heated  by  a  red-hot  surface  without  air,  its  3 
molecules  change  to  the  polymeric  substance,  benzene,  C6H6, 
which  accounts  for  the  presence  of  benzene  in  coal-tar.  When 
mixed  with  the  proper  proportion  of  air  it  ignites  with  a  violent 
explosion.  By  cold  and  pressure  it  condenses  to  a  very  light 
liquid  with  a  high  coefficient  of  expansion.  This  is  classed  by 
some  governments  among  the  dangerous  explosives. 

Detection. — This  depends  upon  the  fact  that  when  passed  into 
a  solution  of  cuprous  chlorid  in  ammonia  it  forms  a  brownish, 
amorphous  copper  acetylid,  C2H2Cu2O;  and  the  dry  powder  ex- 
plodes by  percussion  or  by  heat.  When  absorbed  by  water  the 
acetylene  solution  precipitates  ammoniosilver  nitrate  a  white 
color;  or  ammoniocuprous  chlorid,  red.  It  is  not  poisonous,  as 
a  contaminant  of  the  air,  in  amounts  likely  to  be  inhaled. 


384  ALIPHATIC    COMPOUNDS 


HALOGEN  DERIVATIVES  OF  METHANE 

THE  methane  series  forms  halids  with  iodin,  chlorin,  and  bromin. 
Under  the  influence  of  daylight  upon  a  mixture  of  methane  and 
chlorin  the  following  compounds  are  successively  obtained  and 
hydrochloric  acid  formed: 

Methyl  chlorid        CH3C1  S.  G.  0.952  .  .  B.  P.  —23.7°  C.  (—10.66°  F.). 

Methylene  chlorid  CH2C12  "      1.377  •  •  "      +4i-6°  C.  (106.88°  F.). 

Chloroform              CHC13  "      1.526  .  .  "          61.2°  C.  (142.6°  F.). 

Tetrachlormethane    CC14  "      1.632  .  .  "          76.7°  C.  (170.06°  F.). 

The  reactions  for  the  first  two  are  indicated  in  the  following 
equations: 

(1)  CH*        -f        C12  CH3C1       +        HC1. 

(2)  CH3C1     +         Cla  CH2C12      +        HC1. 

To  indicate  that  these  are  not  additive  compounds  the  follow- 
ing graphic  equations  are  used: 

H  H  Cl  H  H 

X ± I,  X 

H  JH  Cli         — *•        HC1         +      H  Cl 

Methane.  Chlorin.  Methyl  chlorid. 

Another  molecule  of  chlorin  acting  upon  the  methyl  chlorid 
carries  the  change  one  step  further.  Thus: 

H          H  Cl  H  H 

X, ± I.  X 

Cl  !H  Clj         — *•        HC1         +      Cl  Cl 

Methyl  chlorid.  Methylene  chlorid. 

Substitution. — To  produce  the  other  two  derivatives  requires 
the  same  process  of  extracting  hydrogen  and  replacing  it  by 
chlorin,  step  by  step.  This  process  is  called  substitution.  It  is 
very  general  in  the  case  of  organic  compounds;  indeed,  a  system 
of  classifying  them  is  based  upon  the  notion  that  all  organic  sub- 
stances can  be  formed  from  one  another  by  substitution.  This 
process  differs  from  that  of  salt  formation,  where  the  hydrogen  of 
an  acid  is  replaced  by  a  metal.  All  the  hydrogen  of  the  hydro- 
carbons can  be  substituted,  but  this  cannot  be  done  with  the 
hydrogen  of  all  inorganic  acids,  a  few  of  which,  such  as  phospho- 
rous and  hypophosphorous  acids  have  some  hydrogen  that  resists 


HALOGEN    DERIVATIVES    OF    METHANE  385 

substitution  by  a  metal.  The  organic  hydrogen  can  be  replaced  by 
all  sorts  of  elements  and  groups,  while  that  of  acids  only  by  metals 
or  metal-like  compounds.  These  substitution  products  are  not 
dissociable  like  the  mineral  salts,  though  some  organic  acids, 
bases,  and  salts  behave  in  the  same  way  as  the  inorganic  com- 
pounds. 

General  Properties.— The  table  of  chlorids  shows  that  the 
halogen  derivatives  of  the  hydrocarbons  increase  in  density  and 
boiling-point  progressively  with  the  proportion  of  chlorin,  bromin, 
or  iodin.  None  of  them  is  a  salt;  none  of  them  conducts  elec- 
tricity. They  are  sparingly  soluble  and  their  solutions  do  not  give 
the  reaction  of  the  ions  of  chlorin  and  bromin  with  silver  nitrate. 

Radicals.— In  the  above  list  we  start  with  methane,  CH4; 
hence  the  substitution  products  are  sometimes  named  as  though 
they  were  species  of  methane.  Thus  CH3C1  is  chlormethane; 
CH2C12,  dichlormethane;  CHC13,  trichlormethane;  and  CC14, 
tetrachlormethane.  They  are  sometimes  considered  to  be  chlorids 
of  the  groups  CH3,  CH2,  CH,  and  the  element  C.  The  C  takes  4 
atoms  of  chlorin,  which  accords  with  the  recognized  tetravalence 
of  carbon.  In  all  these  compounds  this  valence  is  evident.  The 
group  CHEE  combines  with  3,  and  hence  is  trivalent;  CH2=  with 
2,  divalent;  and  CH3 —  with  i,  monovalent.  These  groups  do  not 
exist  in  the  free  state,  but  when  combined  as  above  hold  together 
through  many  changes  and  reactions,  with  evidences  of  persistent 
identity.  These  methane  radicals  are  named  as  follows:  CH3, 
methyl;  CH2,  methylene;  CH,  methenyl.  The  monovalent  groups, 
such  as  methyl,  ethyl,  propyl,  etc.,  are  called  alkyl,  or  alcoholic 
radicals,  and  they  are  often  indicated  by  the  letter  R.  The  name 
alkylene  is  given  to  the  divalent  radicals,  such  as  methylene, 
ethylene,  propylene,  etc.  Other  radicals  of  a  different  order  are  the 
monovalent  hydroxyl,  —OH;  carboxyl,  —  COOH;  cyanogen, 
-CN;  acetyl,  -COCH3,  and  the  divalent  carbonyl,  =CO. 

Methyl  chlorid,  CH3C1  (monochlor methane},  is  a  colorless  gas 
of  sweetish  odor  and  taste,  inflammable,  burning  with  a  greenish 
flame.  Liquefied  by  pressure,  it  is  applied  locally  for  neuralgia, 
producing  intense  cold  by  its  evaporation. 

Methylene  bichlorid,  CH2C12  (dichlormethane),  an  ethereal 
fluid,  is  an  effective  anesthetic,  but  dangerous,  as  it  paralyzes  the 
heart. 

Carbon  tetrachlorid,  CC14  (tetrachlormethane),  is  a  colorless 
liquid  having  anesthetic  properties.  It  is  dangerous  because  of 
its  effects  on  the  heart. 

Chloroform   (CHC13)  (Trichlormethane).— -The  most  important 
of  the  halogen  derivatives  of  methane  are  the  trisubstitution  prod- 
ucts: chloroform,  iodoform,  bromojorm. 
25 


386  ALIPHATIC    COMPOUNDS 

Preparation.  —  The  method  of  obtaining  chloroform  by  direct 
action  of  chlorin,  while  of  great  interest  theoretically,  is  not  con- 
venient nor  economic.  It  is  prepared  by  distilling,  over  a  water- 
bath,  ethyl  alcohol  or  acetone  with  calx  chlorinata,  in  a  large  flask 
fitted  to  a  condenser.  Chloroform  and  water  distil  over  and 
separate  by  difference  of  density,  chloroform  being  one  and  one- 
half  times  heavier  than  water. 

The  reaction  with  alcohol  is  complex,  that  with  acetone  is  as 
follows: 


Acetone.  Chloroform.  Calcium  acetate. 

Properties.  —  Chloroform  is  a  colorless  volatile  liquid  with  a 
sweetish  taste  and  characteristic  odor.  Its  specific  gravity  is 
1.491.  It  is  neutral  in  reaction,  sparingly  soluble  in  water,  dis- 
solving in  5  volumes  of  alcohol,  and  mixes  in  all  proportions  with 
ether,  benzin,  and  oils.  It  does  not  flash  at  ordinary  tempera- 
tures, but  burns  at  very  high  temperatures  with  a  green  flame.  It 
boils  at  62°  C.  (143.6°  F.).  Mixed  with  a  little  air,  in  a  bottle, 
and  exposed  to  diffused  daylight,  it  decomposes  easily;  to  prevent 
this  it  is  best  kept  in  amber-colored  bottles  or  opaque  containers. 
It  keeps  better  when  i  per  cent,  of  alcohol  is  added. 

When  used  for  inhalation  near  an  exposed  flame  the  same 
dangerous  irritant  products  of  decomposition  are  formed  as  when 
kept  for  a  long  time  exposed  to  daylight: 

CHC13        +        O  COC12        +        HC1. 

Chloroform.  Carbonyl  chlorid. 

This  carbonyl  chlorid,  or  phosgene  gas,  may  be  the  cause  of  fatal 
poisoning. 

Chloroformum  venale,  is  the  commercial  article,  which  con- 
tains sundry  hydrocarbons,  free  chlorin,  aldehyd,  and  hydrochloric 
acid.  These  enhance  the  toxicity  and  render  it  unfit  for  inhala- 
tion. 

Chloroformum,  U.  S.  P.,  is  purified  for  inhalation  and  con- 
tains about  i  per  cent,  of  alcohol.  Dose,  internally:  2  to  20  tTL 
(0.12-1.25  c.c.);  when  inhaled:  i  fl.  dr.  (3.75  c.c.),  repeated. 

Tests  for  Impurities.  —  A  lower  specific  gravity  than  1.48  indi- 
cates too  much  alcohol.  After  shaking  with  one-half  volume  of 
water,  separate  and  test  the  water  with  litmus-paper.  If  red,  then 
hydrochloric  acid  is  present  —  confirmed  with  silver  nitrate,  which 
precipitates  white  with  chlorin  and  hydrochloric  acid.  Mix  and 
shake  frequently  with  an  equal  volume  of  pure  sulphuric  acid 
and  set  aside  for  one  hour.  If  the  acid  separate  with  a  brown 
color,  then  organic  impurities  are  present.  Shaken  with  potas- 
sium hydroxid,  it  turns  brown  if  aldehyd  be  present. 


HALOGEN    DERIVATIVES    OF    METHANE  387 

Aqua  chlorojormi,  U.  S.  P.,  is  a  saturated  aqueous  solution. 
Dose:  4  fl.  dr.  (16  c.c.). 

Spiritus  chlorojormi,  U.  S.  P.,  is  the  alcoholic  solution  con- 
taining 6  per  cent  of  chloroform.  Dose  30  til  (2  c.c.). 

EmuLsum  chloroformi,  U.  S.  P.,  contains  4  per  cent,  of  chloro- 
form suspended  in  a  mucilage  of  tragacanth  and  oil  of  almond. 

Linimentum  chlorojormi,  U.  S.  P.,  contains  chloroform,  30  parts, 
and  soap  liniment,  70  parts. 

Symptoms. — The  irritant  action  is  shown  by  the  pain  in  the 
throat  and  stomach,  with  or  without  vomiting.  The  symptoms 
of  gastro-enteritis  are  soon  marked.  Some  of  the  vapor  is  inhaled 
and  the  liquid  itself  is  quickly  absorbed,  inducing  the  neurotic 
symptoms.  These  may  be  ushered  in  by  a  short  period  of  excite- 
ment, or  may  begin  at  once  with  the  characteristic  stupor.  The 
vomiting  soon  ceases;  the  breathing  becomes  irregular  and  snor- 
ing; the  pulse  thready;  the  pupils  either  dilated  or  contracted; 
the  skin  clammy  and  livid.  If  the  patient  recover  from  the  coma, 
the  abdominal  pain  again  becomes  urgent.  This  is  often  attended 
by  diarrhea  and  jaundice. 

Treatment. — The  stomach  should  be  emptied  by  the  siphon 
tube  or  by  vomiting  induced  with  hypodermic  injections  of  3  to  5 
min.  of  a  2  per  cent,  solution  of  apomorphin  hydrochlorid.  For 
a  draught  and  to  wash  out  the  stomach,  the  best  antidote  is  a 
solution  of  a  tablespoonful  of  sodium  bicarbonate  to  a  tumblerful 
of  water.  The  failing  heart  must  be  stimulated  with  hypodermic 
injections  of  2  or  3  drops  of  a  fresh  2-per  cent,  solution  of  strychnin 
nitrate.  The  chest  may  be  flicked  strongly  at  intervals  with  a 
wet  towel,  alternating  with  hot  applications  to  the  chest  and 
abdomen.  Electricity  and  artificial  respiration  are  called  for 
when  the  respiration  is  suspended.  After  recovery  from  coma 
the  symptoms  of  gastro-enteritis  must  be  treated  as  they  arise. 

Fatal  Dose. — By  the  stomach  the  smallest  fatal  dose  is  i  fl.  dr., 
given  to  a  boy  four  years  old.  For  an  adult  the  least  quantity 
swallowed  that  has  killed  is  about  i  fl.  oz.  Recovery  has  fol- 
lowed when  the  dose  was  as  much  as  4  fl.  oz. 

Fatal  Period. — Usually  death  is  delayed  for  twelve  hours, 
though  it  has  occurred  within  three  hours. 

Toxicology  when  Inhaled  as  Vapor. — Given  as  an  anesthetic 
in  surgical  practice,  chloroform  has  caused  many  deaths.  Sta- 
tistics warrant  the  estimate  that  i  case  out  of  3000  inhalations  will 
probably  be  fatal.  It  is  difficult,  but  not  impossible,  to  admin- 
ister chloroform  to  a  person  in  very  deep  natural  sleep.  The 
odor  usually  arouses  before  a  stupefying  quantity  has  been  inhaled. 
It  takes  between  five  and  ten  minutes  in  time,  and  between  3  and 
4  fl.  dr.  in  i-dr.  doses  to  produce  insensibility. 


388  ALIPHATIC    COMPOUNDS 

Symptoms. — After  a  short  period  of  excitement  there  follows 
one  of  lowered  activity  of  the  brain  and  later  of  the  spinal  cord. 
Sensation  is  lost  early  and  the  muscles  are  completely  relaxed. 
Breathing  is  affected  in  the  third  stage  and  the  heart's  action  is 
depressed.  The  temperature  declines,  the  skin  becomes  livid,  and 
if  the  anesthesia  be  prolonged,  death  may  ensue  from  failure  of 
respiration  or  cessation  of  the  heart's  activity.  Some  fatalities  are 
traceable  to  the  cases  being  obviously  unfit  from  old  age,  heart 
disease,  diabetes,  Bright's  disease,  and  alcoholism.  It  is  dangerous 
to  give  chloroform  in  quantities  greater  than  i  fl.  dr.  or  undiluted 
with  air.  The  blood  quickly  absorbs  it,  and  the  centers  that 
actuate  and  control  breathing  and  the  heart's  action  are  paralyzed. 
Vomiting  often  occurs  and  the  matter  may  choke  the  larynx. 

Fatal  Dose. — This  depends  on  the  concentration.  Death  has 
ensued  when  only  15  drops  were  inhaled  without  air.  It  is  hardly 
safe  to  give  it  in  a  stronger  proportion  than  4  parts  in  100  of  air. 
On  the  other  hand,  recovery  has  been  brought  about  after  the 
inhalation  of  20  oz.  properly  diluted,  and  the  administration 
distributed  over  twelve  or  more  hours. 

It  is  dangerous  to  use  chloroform  by  the  open  flame  of  a  candle 
or  gas  burner.  Its  vapor  is  burned  into  the  irritating  and  suffo- 
cative  fumes  of  carbonyl  chlorid,  COC12,  and  hydrochloric  acid. 
If  the  operation  and  inhalation  are  prolonged,  the  patient,  the 
physician,  and  nurses  may  all  show  signs  of  poisoning,  such  as 
cyanosis,  difficult  breathing,  cough,  collapse,  and  even  death  some 
hours  after. 

Treatment. — When  the  breathing  or  the  pulse  suddenly  de- 
clines there  is  need  of  artificial  respiration  with  oxygen  inhalation. 
The  head  should  be  lowered,  the  tongue  drawn  forward,  and 
strychnin  given  hypodermically. 

Tests  for  Chloroform. — (i)  A  drop  of  chloroform  added  to  a 
mixture  of  i  drop  of  anilin  and  alcoholic  potassium  hydroxid 
and  gently  warmed  develops  a  nauseous  smell  of  isobenzonitril: 

CHC13  +  C6H5NH2  +  3KOH  =  C6H5NC  +  3KC1  +  3H2O. 

Anilin.  Isobenzonitril. 

A  distinctly  offensive  odor  can  be  perceived  when  the  chloro- 
form is  present,  i  :  5000. 

Fallacies. — The  same  reaction  can  be  obtained  from  iodoform, 
bromoform,  chloral,  and  trichloracetic  acid. 

(2)  A  reagent  is  made  by  mixing  0.3  gm.  of  resorcinol  in  3  c.c. 
of  water  and  3  drops  of  10  per  cent,  sodium  hydroxid.  When 
this  is  boiled  strongly  with  i  drop  of  chloroform  it  becomes  yel- 
lowish red,  with  a  beautiful  greenish  fluorescence. 


HALOGEN    DERIVATIVES    OF    METHANE 


389 


(3)  Having  dissolved  about  o.oi  gm.  of  beta-naphthol  in  strong 
potassium  hydroxid  and  warmed  it,  add  the  chloroform.     A  blue 
color  results,  changing  to  green  and  brown. 

(4)  Ragsky  Test. — When  death  is  supposed  to  have  been  due 
to  inhalation  of  chloroform,  the  lungs  should  be  cut  up  finely  and 
mixed  with  a  small  quantity  of  water.     A  flask  is  provided  with 
a  cork,  perforated  to  admit  a  funnel  tube  passing  to  the  bottom,  and 
a  short  delivery  tube  at  the  top  (Fig.  76).     The  lung  mixture,  made 
alkaline  with  sodium  carbonate  to  fix  volatile  acids  and  free  chlo- 
rin,  is  heated  in  the  flask  over  a  water-bath.     The  delivery  tube  is 
connected  with  a  larger  hard  glass  tube,  about  18  in.  long,  which 
must  be  heated  to  bright  redness  through  4  in.  of  its  length  by 


FIG.  76. — Apparatus  for  detecting  chloroform  by  the  Ragsky  process. 

a  broad-flamed  Bunsen  burner.  About  4  in.  further  along  the 
tube  is  cooled  by  a  condenser  or  by  wetting  a  piece  of  muslin,  i  in. 
wide,  wound  about  the  tube.  In  the  tube,  beyond  the  muslin,  is 
placed  a  moist  piece  of  iodized  starch  test-paper.  The  end  of  the 
tube  connects  with  Geissler's  bulbs  or  a  wash  bottle  containing 
silver  nitrate  solution,  and  the  exit  tube  of  the  bottle  is  connected 
with  an  aspirator.  The  flask  is  heated,  and,  after  the  tube  is  red 
hot,  air  is  drawn  slowly  through  the  whole  apparatus  by  the  aspir- 
ator. It  carries  air  and  chloroform  to  the  hot  tube,  where  the 
vapor  decomposes  into  perchlorbenzene,  hydrochloric  acid,  and 
chlorin,  according  to  the  following  reaction: 


6CHCL 


=        C6C16 


6HC1 


+        6C1. 


390  ALIPHATIC    COMPOUNDS 

The  perchlorbenzene  is  deposited  as  needles  in  the  cold  tube, 
the  chlorin  liberates  iodin  from  potassium  iodid,  turning  the  paper 
blue,  and  the  hydrochloric  acid  precipitates  the  silver  nitrate. 

(5)  Fehling's  solution,  when  boiled,  is  reduced  by  chloroform  to 
red  cuprous  oxid. 

lodoform  (CHI3)  (tri-iodo  methane)  is  closely  related  to  chlo- 
roform, chemically.  It  is  formed  when  ethyl  alcohol,  aldehyd, 
acetone,  and  some  other  organic  substances  are  warmed  with 
iodin  and  potassium  hydroxid  or  carbonate: 


Alcohol.  Potassium  formate. 

Experiment.  —  A  few  drops  of  alcohol  are  added  to  a  small 
quantity  of  5-per  cent,  solution  of  sodium  carbonate,  and  the 
mixture  warmed.  Iodin  (Lugol's  solution),  added  gradually, 
causes  the  separation  of  iodoform. 

Properties.  —  It  is  precipitated  in  the  above  experiment  as 
lustrous  yellowish  crystals  in  the  form  of  six-sided  plates  having 
a  disagreeable  odor  of  saffron  and  an  unpleasant  taste  of  iodin. 
It  melts  at  119°  C.  (246.2°  F.),  sublimes  readily,  and  is  volatile  at 
ordinary  temperatures.  It  is  insoluble  in  water,  but  soluble  in 
alcohol  and  ether. 

Toxicology.  —  lodoform  is  extensively  used  in  surgical  dressings 
because  of  its  antiseptic  and  local  anesthetic  powers.  Used  too 
freely,  it  has  been  absorbed  with  poisonous  results.  Some  of  this 
action  is  due  to  iodin  set  free  in  the  wounds  and  appearing  later 
in  the  urine  and  saliva. 

Symptoms.  —  In  certain  persons  excessive  use  of  iodoform  dres- 
sings has  produced  local  irritant  effects  about  the  wound,  marked  by 
redness,  pain,  swelling,  diffused  eruptions,  inflamed  lymphatics, 
and  even  death.  The  systemic  phenomena  are  mainly  cerebral; 
they  are  malaise,  nausea,  wakefulness,  giddiness,  headache, 
depression  of  spirits,  melancholic  delusions,  delirium,  coma, 
collapse,  and  death.  Occasionally  the  type  is  different,  the  group 
of  symptoms  being  drowsiness,  stupor,  and  collapse. 

Fatal  Dose.  —  Taken  internally,  30  gr.  have  caused  death,  though 
recovery  has  followed  a  dose  of  120  gr.  It  is  not  regarded  as 
safe  to  apply  more  than  i  dr.  at  a  time  to  a  wound  or  absorbing 
surface. 

Fatal  Period.  —  Death  may  follow  after  several  days'  illness,  or 
life  may  be  prolonged  for  weeks. 

Treatment.  —  The  first  indication  is  to  clear  out  the  wound,  but 
the  gravest  symptoms  may  continue,  notwithstanding  removal  of 
the  iodoform.  The  nervous  phenomena  must  be  treated  accord- 


HALOGEN    DERIVATIVES    OF    ETHANE  391 

ing  to  their  nature.  Hypodermic  injections  of  normal  salt  solu- 
tion are  of  benefit. 

Postmortem  Appearances. — Acute  inflammation  of  the  kidneys 
and  pulmonary  edema  have  been  found,  but  most  commonly  there 
is  fatty  change  in  the  kidneys,  heart,  and  liver. 

Detection. — Mixed  with  an  alcoholic  solution  of  potassium 
hydroxid  and  kept  warm  for  a  while,  iodoform  yields  free  iodin  after 
acidifying  with  nitric  acid.  The  very  characteristic  odor  may 
lead  to  prompt  detection.  If  this  be  not  perceived,  the  suspected 
matter  is  digested  in  water,  made  alkaline,  and  distilled.  The 
distillate  is  again  made  alkaline,  agitated  with  ether,  and  the 
ethereal  extract  evaporated,  leaving  six-sided  lemon-yellow  tablets 
and  stars. 

Bromoform  (CHBr3)  (tribrom-methane)  is  formed  by  a  reaction 
like  that  of  preparing  chloroform  (p.  386),  using  the  action  of  alkali 
hypobromites  on  alcohol  or  acetone. 

Properties, — It  is  a  colorless,  heavy  liquid  with  a  sweetish 
odor  and  taste,  like  that  of  chloroform.  By  exposure  it  turns 
dark  from  liberation  of  bromin.  It  is  scarcely  soluble  in  water, 
but  soluble  in  alcohol  and  ether. 

Toxicology. — Bromoform  is  used  in  medical  practice  as  an 
antispasmodic  and  sedative  in  the  treatment  of  whooping-cough. 
Dose,  for  a  child:  2  to  5  drops  (0.12-0.3  c.c.)  in  dilute  alcohol 
or  emulsions.  After  a  dose  of  15  lit  a  child  of  four  years  be- 
came unconscious,  with  contracted  pupils,  labored  breathing, 
and  livid  complexion.  The  child  recovered  after  evacuation  of 
the  stomach  and  stimulation  by  warmth,  electricity,  and  coffee. 


HALOGEN  DERIVATIVES  OF  ETHANE 

Ethyl  chlorid  (C2H5C1)  (chlorethane}  is  formed  by  the  action 
of  sunlight  on  a  mixture  of  ethane  and  chlorin;  or  by  the  action 
of  phosphorus  pentachlorid  on  ethyl  alcohol: 

C2H5OH    +    PC15    =    C2H5C1    +    POC13    +    HC1. 

Ethyl  alcohol.          Phosphorus  Phosphorus 

pentachlorid.  oxychlorid. 

Ethyl  chlorid  is  a  gas  at  ordinary  temperature.  Under  pressure 
it  becomes  a  colorless,  very  volatile  liquid,  boiling  at  12.5°  C. 
(55°  F.).  It  is  soluble  in  ether  and  alcohol,  but  only  sparingly  so 
in  water.  It  does  not  precipitate  silver  nitrate  in  aqueous  solution, 
as  it  has  no  chlorin  ions,  but  when  warmed  with  an  alcoholic 
solution  of  silver  nitrate  it  throws  out  silver  chlorid.  Heated  with 


3Q2  ALIPHATIC    COMPOUNDS 

water  or  potash,  under  pressure,  it  yields  ethyl  alcohol.  Com- 
pressed as  a  liquid  in  tubes,  the  vapor  is  expelled  through  a  small 
opening,  to  play  upon  painful  parts  as  a  local  anesthetic.  It  is 
highly  inflammable. 

Ethyl  Bromid  (C2H5Br)  (Bromethane,  Hydrobromic  Ether). 
— This  compound  can  be  formed  by  the  same  reactions  as  ethyl 
chlorid,  substituting  bromin  for  chlorin.  It  is  a  colorless,  heavy, 
volatile  liquid,  with  a  burning  taste  and  a  pleasant  smell,  like  that 
of  chloroform.  It  is  miscible  with  alcohol,  ether,  and  chloroform. 
It  behaves  like  ethyl  chlorid  with  water,  potash,  and  silver  nitrate. 
Exposed  to  light  and  air  it  turns  yellow  and  decomposes,  as 
chloroform  does,  into  dangerous  compounds.  When  inhaled  it 
causes  rapid  anesthesia  with  quick  recovery. 

Dose,  for  inhalation,  2  to  3  fl.  dr.  (7.50-11.25  c.c.);  by  the  mouth, 
5  to  10  drops  on  sugar.  It  is  not  a  safe  anesthetic,  as  death  has 
happened  once  in  about  4000  cases.  It  has  occurred  in  less  than 
a  minute;  but,  on  the  other  hand,  has  been  delayed  for  days. 
Ethyl  bromid  boils  at  39°  C.  (102.2°  F.),  and  so  easily  breaks 
up  by  the  heat  that  isolation  by  distillation  is  extremely  difficult. 
The  disubstitution  compound,  C2H4Br2,  ethylene  bromid,  has  been 
given  for  it  by  mistake.  This  is  more  depressing  to  the  heart,  and 
therefore  more  poisonous. 

Ethyl  lodid  (C2H5I)  (lodethane,  Hydriodic  Ether).— This  is 
a  clear,  pleasant-smelling,  neutral  liquid,  which  rapidly  turns 
brown  when  exposed  to  light  and  air,  liberating  iodin.  Chemi- 
cally, it  resembles  the  chlorid  and  bromid.  Insoluble  in  water,  it 
dissolves  in  alcohol  and  ether.  It  is  given  by  the  stomach  in 
doses  of  5  to  16  min.  (0.3-1  c.c.),  as  an  antispasmodic.  Inhaled, 
10  to  20  drops  at  a  time,  it  allays  bronchial  irritation.  It  must  be 
given  with  caution,  for  it  depresses  the  heart  in  excessive  doses. 


OXYGEN   DERIVATIVES 

Alcohols,  Ethers,  Aldehyds,  Acids 

ALCOHOLS 

Methyl  Alcohol  (CH3OH)  (Wood  Spirit,  Wood  Naphtha).- 
The  name  alcohol  was  formerly  sacred  to  the  spirit  oj  wine,  the 
volatile  and  stimulating  essence  of  intoxicating  beverages.  Chem- 
ists having  concluded  that  it  was  a  compound  of  the  radical  hy- 
droxyl,  HO,  with  a  hydrocarbon  radical,  the  name  was  extended  to 
other  compounds  of  like  composition,  classing  them  as  the  alcohols. 


ALCOHOLS  393 

To  distinguish  organic  hydroxids  the  syllable  "-ol"  is  used  as 
a  suffix.  Thus:  methanol  for  methyl  alcohol,  ethanol  for  ethyl 
alcohol. 

When  dry  wood  is  heated  in  retorts  and  the  distilled  vapors 
are  condensed,  among  the  volatile  products  is  found  methyl  alco- 
hol. By  fractional  distillation  it  is  separated  from  the  creosote 
and  acetic  acid  that  were  mixed  with  it.  It  is  a  thin,  colorless 
liquid,  with  a  faint  aromatic  odor  and  a  burning  taste.  Its  specific 
gravity  is  0.796;  boiling-point  66°  C.  (150.8°  F.);  freely  soluble 
in  water.  It  burns  with  a  non-luminous  flame  and  without  soot;  it 
is  used  in  spirit  lamps  for  heating  chafing-dishes,  coffee-urns,  etc. 
It  dissolves  shellac  and  other  resins,  and  is  used  to  make  varnishes. 
For  these  purposes  commercial  forms  are.  found  in  the  shops, 
named  Colonial  spirits,  Columbian  spirits. 

Methylated  spirit  is  a  mixture  used  in  the  arts  under  the  name 
"  denatured  alcohol,"  free  under  the  excise  law  because  the  ethyl 
or  common  alcohol  is  rendered  undrinkable  by  10  per  cent,  of 
methyl  alcohol  with  a  trace  of  benzin.  Pure  methyl  alcohol  has 
been  substituted  by  druggists  for  ethyl  alcohol  in  preparing  es- 
sences of  cinnamon,  ginger,  peppermint,  lemon,  cologne,  and  bay 
rum.  In  certain  States  where  the  sale  of  alcoholic  beverages  is 
prohibited  it  is  a  common  custom  to  drink  these  essences  and 
cologne  spirits  for  the  ethyl  alcohol  they  should  contain  when 
properly  prepared. 

The  physiologic  action  of  methyl  alcohol  differs  from  that  of 
ethyl  alcohol  in  that  the  coma  persists  for  longer  periods.  While 
in  the  body  it  is  oxidized  to  formic  acid,  which  is  eliminated  as 
sodium  formate,  NaCO2H,  a  stronger  poison  than  the  alcohol. 
It  is  formed  and  excreted  so  slowly  that  small  repeated  doses 
overlap  each  other  with  a  cumulative  effect. 

Symptoms. — Its  exhilarating  effect  is  quickly  followed  by  ver- 
tigo, nausea,  vomiting,  headache,  dilated  pupils,  delirium,  per- 
sistent coma,  and  death.  Should  recovery  take  place,  there  is  danger 
of  more  or  less  blindness,  due  to  atrophy  of  the  optic  nerve. 

Fatal  Dose. — Blindness  has  followed  the  taking  of  5  teaspoon- 
fuls  of  methyl  alcohol.  Something  less  than  J  pt.  has  proved  fatal. 

Fatal  Period. — Death  may  occur  in  a  few  hours  or  be  delayed 
two  days. 

Treatment. — With  the  siphon  tube  the  gastric  contents  should 
be  diluted  with  warm  water  and  the  stomach  emptied.  Alterna- 
tions of  hot  and  cold  affusions  may  help  the  coma.  Artificial  res- 
piration may  be  called  for,  and  the  circulation  need  stimulation 
with  strychnin.  The  optic  neuritis  will  be  benefited  by  strychnin 
and  stimulants. 

Test. — Warmed    with    potassium    bichromate    and    sulphuric 


394  ALIPHATIC    COMPOUNDS 

acid,  the  methyl  alcohol  is  oxidized  to  formic  acid.  This  is  sep- 
arated by  neutralizing  the  sulphuric  acid  with  calcium  carbonate 
and  precipitating  the  chromate  with  lead  acetate.  Filtered,  the 
clear  nitrate  is  tested  for  formic  acid  by  warming  it  with  ammonio- 
nitrate  of  silver.  A  silver  mirror  is  formed  on  the  glass. 

Constitution  of  Alcohols. — It  has  been  stated  above  that 
alcohols  are  believed  to  be  the  hydroxids  of  hydrocarbon  radicals. 
The  proof  of  this  structure  rests  upon  certain  reactions  in  which 
the  alcohols  behave  like  metallic  hydroxids.  On  mixing  hydro- 
chloric acid  with  methyl  alcohol  there  is  no  immediate  change. 
After  a  time,  however,  new  chemical  combinations  arise  in  a 
manner  similar  to  those  attending  the  interaction  of  a  metallic 
hydroxid  and  an  acid.  Thus: 

CH40        +        HC1  CH3C1        +        H20. 

Methyl  alcohol.  Methyl  chlorid. 

This  recalls  the  reaction  of  a  hydroxid  base  and  an  acid  forming 
a  salt  and  water: 

KHO         +         HC1  KC1         +         H20. 

The  complete  oxidation  of  methane  by  combustion  is  as  fol- 
lows: 

CH4        +        2O2  CO2        +        2H2O. 

Intermediate  oxidation  products  (its  alcohol,  aldehyd,  and  acid) 
may  be  obtained  by  regulating  the  conditions.  An  alcohol  is  the 
first  stage  derived  by  introducing  i  atom  of  O  into  the  hydro- 
carbon. Thus: 

H  H 

H— C— H      +      O    — >    H— C— O— H 

I  I 

H  H 

Methane.  Methyl  alcohol. 

The  alcohol  is  no  longer  inert,  like  the  hydrocarbon  from  which 
it  was  derived.  The  i  atom  of  H  linked  by  O  to  the  C  is  peculiar. 
It  is  more  loosely  held  than  are  the  others,  and  easily  gives  place 
to  other  elements  or  groups. 

In  the  CH4O  of  methyl  alcohol  there  are  two  groups,  CH3 
methyl,  and  HO  hydroxyl.  Therefore,  it  may  very  properly  be 
written  CH3HO,  the  HO  group  stamping  it  as  an  alcohol.  In 
most  respects  the  alcohols  show  no  basic  properties,  being  neutral 
in  reaction,  non-conductors  of  the  electric  current,  and  undis- 
sociated  into  ions.  Methyl  chlorid  lacks  some  of  the  properties  of 
a  salt.  Its  aqueous  solution  is  a  non-electrolyte,  and  does  not 


ALCOHOLS  395 

precipitate  silver  nitrate.  Therefore,  there  is  no  amount  of  dis- 
sociated chlorin,  such  as  characterizes  metallic  chlorids.  That 
there  is  an  exceedingly  small  percentage  of  chloridion  is  shown  by 
the  circumstance  that  the  mixture  with  silver  nitrate  does,  after 
a  long  time,  throw  down  a  whitish  precipitate.  This  infinitesimal 
amount  of  dissociation  counts  for  something  and,  taken  with  other 
facts,  justifies  the  view  that  alcohols  are  hydroxyl  compounds, 
but  does  not  warrant  the  name  of  salt  for  the  class  of  which  CH3C1 
is  a  representative.  They  are  known  as  esters  (see  p.  430). 

Ethyl  Alcohol  (C2H6O  or  C2H5HO)  (Spirits  oj  Wine,  Grain 
Alcohol,  Ethyl  Hydroxid). — Different  varieties  of  ethyl  alcohol  are 
the  result  of  varying  degrees  of  dilution  with  water.  Absolute 
alcohol  is  free  from  water,  but  that  officially  called  absolute  has 
only  99  per  cent,  of  pure  alcohol.  Alcohol  (U.  S.  P.)  has  a  spe- 
cific gravity  of  0.816  and  contains  94.9  per  cent  by  volume.  This 
is  common  alcohol  or  rectified  spirit.  Alcohol  dilutum  (U.  S.  P.) 
has  a  specific  gravity  of  0.930  and  contains  48.9  per  cent,  by  vol- 
ume. It  has  the  concentration  of  commercial  proof  spirit  and  is 
the  form  used  in  making  some  tinctures. 

Denatured  alcohol,  a  cheap  preparation  of  grain  alcohol,  90  per 
cent.,  is  free  of  internal  revenue  tax  because  it  contains  methyl 
alcohol  10  per  cent,  and  benzin  0.5  per  cent.,  which  make  it  unfit 
for  use  in  beverages  without  impairing  its  value  to  the  arts. 

Preparation. — Ethyl  alcohol  occurs  in  many  beverages  which 
are  made  from  starch  and  the  sweet  juices  of  plants  by  the  action 
of  ferments,  and  is  prepared  in  three  well-defined  stages — malting, 
fermentation,  distillation. 

Malting.— The  starch  of  corn  or  of  other  grain,  of  rice,  or  of 
potatoes  is  mixed  with  malt  and  water  and  keut  for  several  hours 
at  a  temperature  of  about  65°  C.  (150°  F.).  In  three  hours  the 
starch  has  changed  to  dextrin,  maltose,  and  glucose.  This  conver- 
sion is  brought  about  by  a  catalytic  agent  known  as  diastase,  which 
is  generated  in  grains  of  barley  made  into  malt  by  the  process  of 
sprouting.  Diastase  is  a  soluble,  unorganized,  lifeless  principle, 
like  the  pepsin  of  gastric  juice.  It  is  a  type  of  the  enzyms  which 
hasten  chemical  action  by  their  presence: 

3(C6H1005)    +    H20    +    diastase    =    C12H22On    +    C6H10O5 

Starch.  Maltose.  Dextrin. 

The  dextrin  later  changes  to  maltose. 

2(C6H1005)          +         H20  C12H220U. 

Fermentation. — The  sweet  maltose  mixture,  when  cooled,  is 
mixed  with  yeast,  a  minute  plant  which  grows  rapidly,  secreting 


396  ALIPHATIC  COMPOUNDS 

an  enzym,  zymase,  which  causes  the  decomposition  of  the  maltose 
according  to  these  equations: 

(1)  C12H22On         +     H20          =      2(C6H1206) 

Maltose.  Glucose. 

(2)  2(C6H1206)     +     zymase     =     4C2H6O      +     4CO2. 

Glucose.  Alcohol. 

Other  higher  alcohols  are  formed  at  the  same  time  in  small  amount. 

Yeast,  under  the  microscope,  is  seen  to' be  a  mass  of  rounded 
living  cells  grouped  in  clusters.  In  saccharine  solutions  containing 
proteid  matter  and  phosphates  these  cells,  called  saccharomyces, 
bud,  divide,  and  send  up  spore-bearing  stems.  This  plant  does 
not  grow  freely  at  temperatures  below  5°  C.  (41°  F.)  or  above 
30°  C.  (86°  F.).  Kept  within  these  limits,  the  fluid  gives  off 
bubbles  of  carbon  dioxid  as  if  boiling;  hence  the  name  fermenta- 
tion (jervere  =  to  boil).  Above  30°  C  (86°  F.)  the  alcoholic 
fermentation  declines,  but  plants  different  from  the  yeast  cell 
thrive,  causing  butyric  and  other  decompositions.  These  also 
are  called  fermentations,  according  to  the  definition:  fermentation 
is  a  transformation  of  an  organic  substance,  brought  about  by  an 
enzym  produced  by  living  cells. 

The  plant  called  mycoderma  aceti  secretes  an  enzym  which 
changes  alcohol  to  vinegar;  the  plant  inducing  the  lactic-acid 
fermentation  is  called  the  lactic  ferment. 

Another  form  of  fermentation  is  putrefaction,  a  fetid  decom- 
position of  dead  nitrogenous  organic  substances  induced  by  the 
growth  of  bacteria.  The  products  of  putrefaction  are  the  foul- 
smelling  gases  NH3  :  H2S  :  NH4HS.  Three  conditions  must  be 
present  to  bring  about  any  of  these  fermentations  in  their  proper 
media:  (i)  The  specific  living  organism  secreting  the  ferment; 
(2)  a  favorable  temperature,  not  below  5°  C.  (41°  F.)  nor  above 
90°  C.  (194°  F.);  (3)  moisture.  To  preserve  fermentable  organic 
substances  unchanged  one  or  more  of  these  three  factors  must  be 
eliminated:  (i)  germs,  by  killing  them  with  antiseptics  or  by 
heating  to  90°  C.  (194°  F.)  (above  their  death-point)  and  ex- 
cluding new  spores;  (2)  warmth,  by  refrigerators;  (3)  moisture, 
by  drying  out  the  water,  as  is  done  for  dried  fruit  or  meat. 

Distillation. — The  fermented  fluid  having  changed  to  a  weak 
solution  of  alcohol  is  subjected  to  fractional  distillation.  The 
first  distillate  contains  80  to  90  per  cent,  of  ethyl  alcohol  and  a 
small  amount  of  the  higher  alcohols,  called  fusel  oil.  To  get  rid 
of  the  fusel  oil  the  raw  spirit  is  filtered  through  charcoal  and  again 
distilled,  reserving  the  middle  runnings  as  rectified  spirit. 

Fermented  Beverages. — From  malted  grains  and  flavored  with 


ALCOHOLS  397 

hops  are  made  beer,  ale,  and  porter,  containing  alcohol  from  i  to 
8  per  cent.  From  the  juice  of  the  grape  come  the  wines  of  dif- 
ferent alcoholic  strength:  hock,  8  per  cent.;  claret,  7  per  cent.; 
sherry,  16  per  cent.;  port,  20  per  cent.  From  cider  a  hard  or 
fermented  liquor  is  developed  of  3  to  7  per  cent,  alcohol. 

Ardent  spirits  are  liquors  distilled  so  as  to  separate  the  alcohol 
and  volatile  flavoring  from  the  water,  non-volatile  organic  matter, 
and  inorganic  salts.  Brandy  (spts.  vini  gallici,  U.  S.  P.)  is  dis- 
tilled from  wine  and  has  50  per  cent,  alcohol.  Whisky  (spts. 
jrumenti,  U.  S.  P.)  is  obtained  from  fermented  grain  and  has  50 
per  cent,  alcohol.  Gin  (spts.  juniperi,  U.  S.  P.)  is  distilled  from 
malted  grain  flavored  with  juniper  and  contains  40  per  cent. 
Rum  has  45  per  cent,  and  is  distilled  from  fermented  molasses. 
Liqueurs  or  cordials  are  alcoholic  spirits  made  aromatic  and 
sweetened. 

Properties. — Pure  alcohol  is  a  colorless,  volatile  liquid  of  an 
agreeable  odor  and  burning  taste.  It  quickly  absorbs  water  from 
the  air  and  mixes  with  it  in  all  proportions.  It  boils  at  78.5°  C. 
(173.3°  F-)  and  freezes  at  —130°  C.  (  —  202°  F.).  It  burns  with 
a  non-luminous  flame  and  without  soot.  It  is  a  solvent  for  many 
substances,  gases,  resins,  essences,  and  alkaloids.  It  is  a  starting- 
point  for  making  many  medicinal  and  industrial  chemicals. 

Toxicology. — As  a  poison,  alcohol  ranks  among  the  most  im- 
portant because  of  the  prevalence  of  the  habit  of  alcoholic  excess 
and  because  of  the  diseases  engendered  by  long-continued  use. 
The  cases  of  acute  alcoholism  are  especially  apt  to  follow  excessive 
doses  of  ardent  spirits,  which  may  contain  fusel  oil  in  addition  to 
the  ethyl  alcohol. 

Physiologic  Effects. — In  concentrated  forms  it  is  a  local  irri- 
tant to  the  stomach,  withdrawing  water  from  the  tissues  and 
coagulating  albumin.  When  absorbed  in  large  doses  it  is  a  cardiac, 
respiratory,  and  cerebral  depressant.  Doses  equal  to  J  fl.  oz. 
absolute  are  almost  entirely  oxidized  in  the  body  in  five  hours, 
supplying  the  place  of  the  carbohydrates  of  food.  Taken  in  larger 
amounts,  50  per  cent,  is  eliminated,  for  the  most  part  unchanged, 
by  the  lungs  and  kidneys. 

Symptoms  oj  Acute  Alcoholism. — When  first  seen  by  the  phy- 
sician, the  patient  is  in  profound  stupor.  He  is  said  to  be  dead 
drunk,  and  the  odor  of  alcohol  may  be  detected  upon  his  breath. 
There  is  a  history  of  the  following  symptoms:  Confusion  of  the 
mind  with  flushing  of  the  face,  nervous  excitement  and  tottering 
gait,  vertigo,  foolish  speech,  muscular  weakness,  ending  in  deep 
stupor.  On  recovery  from  the  sleep,  nausea,  headache,  and  vom- 
iting are  usually  experienced.  Though  the  pupils  are  usually 
dilated  they  are  sometimes  contracted  up  to  the  last  moment.  It 


398  ALIPHATIC  COMPOUNDS 

is  a  good  sign  when  the  pupils  are  sensitive  to  light.  Death  from 
shock  may  follow  in  a  few  minutes  after  taking  a  pint  of  undiluted 
whisky  at  one  time.  When  death  is  not  immediate  it  may  occur 
from  coma  and  syncope  or  asphyxia. 

Fatal  Dose. — Taken  at  one  draught,  a  dose  of  ardent  spirits 
containing  5  fl.  oz.  of  absolute  alcohol  may  prove  fatal.  A  half- 
pint  of  gin  has  been  fatal  to  an  adult.  The  equivalent  of  2  fl.  oz. 
of  absolute  alcohol  would  probably  be  deadly  to  a  child  of  ten 
years. 

Fatal  Period. — Death  has  occurred  in  a  few  minutes;  usually 
it  comes  on  in  ten  hours,  though  several  days  may  elapse  before 
the  final  symptoms. 

Treatment. — The  first  indication  is  to  wash  out  the  stomach 
through  the  siphon  tube,  or  to  cause  vomiting  by  emetics.  Cold 
and  hot  affusions  may  be  alternated,  and  warm  applications  main- 
tained to  the  extremities.  Strychnin,  hypodermically,  may  be  of 
service  to  sustain  the  heart. 

Postmortem  Appearances. — The  odor  of  alcohol  is  perceptible 
in  the  internal  organs.  Red,  congested,  and  inflamed  areas  are 
seen  in  the  stomach  lining.  The  lungs  are  usually  dropsical.  The 
brain  and  meninges  may  be  congested  and  edematous,  with  venous 
engorgement  and  extravasation  of  blood. 

Detection  of  Ethyl  Alcohol. — While  the  odor  is  characteristic, 
this  may  be  due  to  whisky  given  as  a  remedy  for  the  early  symp- 
toms of  some  other  condition  ending  in  coma,  such  as  opium- 
poisoning,  uremia,  diabetes,  cerebral  hemorrhage,  or  concussion 
of  the  brain.  Being  volatile,  the  alcohol  may  be  separated  by 
acidifying  the  materials  with  tartaric  acid  and  distilling  steam 
from  another  flask.  The  distillate  is  next  treated  with  magnesium 
oxid  and  redistilled  over  the  water-bath. 

Tests. — lodojorm  Test. — The  alcoholic  liquid  is  mixed  with  a 
few  drops  of  solution  of  iodin  in  potassium  iodid,  and  then  enough 
potassium  hydroxid  is  added  to  decolorize  it.  On  gently  warming 
the  mixture  yellow  crystals  of  iodoform  are  precipitated.  The 
crystals  have  the  odor  of  saffron  and  are  hexagonal  in  form.  The 
same  reaction  can  be  obtained  from  aldehyd,  lactic  acid,  and 
acetone.  ^^^^^wy^  ~ 

Bichr ornate  Test:. — If  an  aqueous  solution  of  alcohol  be  added 
to  a  mixture  of  potassium  bichromate  solution  and  sulphuric  acid, 
the  yellow  color  turns  green  from  the  chromium  sulphate  formed, 
and  the  odor  of  aldehyd  arises,  changing  to  that  of  acetic  acid. 

Acetic  Ether  Test. — Some  crystals  of  sodium  acetate  are  added 
to  the  alcoholic  solution  and  the  mixture  treated  with  sulphuric 
acid  and  warmed;  the  odor  of  acetic  ether  is  perceived. 

Ethyl  Benzoate  Test.—  A  drop  of  benzoyl  chlorid  is  shaken  with 


ALCOHOLS  399 

the  alcoholic  liquid  and  warmed  with  sodium  hydroxid  to  remove 
excess  of  the  chlorid.  The  odor  of  ethyl  benzoate  is  evolved. 

Amyl  alcohol,  C5HUHO,  is  the  pentacarbon  member  of  the 
alcohol  series.  In  small  amount  it  is  a  product  of  the  yeast  fer- 
mentation in  the  starch  of  corn  and  potatoes.  In  company  with 
butyl  alcohol  it  is  found  in  an  impure  mixture  known  commonly 
as  fusel  oil,  oil  of  grain,  oil  of  potatoes.  As  it  has  a  higher  boiling- 
point  than  ethyl  alcohol,  it  comes  over  in  the  last  stages  of  distil- 
lation of  that  spirit.  A  colorless  oily  liquid,  it  has  a  characteristic 
unpleasant  odor  and  an  acrid  taste.  It  is  insoluble  in  water, 
floating  like  an  oil.  In  fusel  oil  there  are  two  physical  isomers  of 
amyl  alcohol,  one  which  does  not  affect  the  plane  of  polarized 
light,  and  the  other  which  turns  it  to  the  right  and  which  boils 
two  degrees  higher.  By  oxidizing  agents  amyl  alcohol  is  con- 
verted to  valeric  acid: 

C5HUHO        +       20  H20       +       C5H1002. 

It  is  believed  that  some  of  the  injurious  effects  of  drinking  raw 
whisky  and  potato  spirit  are  attributable  to  the  presence  of  this 
substance  with  aldehyd.  Headache,  giddiness,  and  nausea  are 
among  the  sequels  of  intoxication  when  fusel  oil  is  present.  In 
cases  of  well-marked  poisoning  the  most  prominent  symptoms  are 
coma,  lasting  several  hours,  followed  by  glucose  in  the  urine.  It 
has  caused  dark  urine  from  the  presence  of  methemoglobin. 

In  time  changes  take  place  in  the  fusel  oil  of  raw  whisky  which 
deprive  it  of  poisonous  properties  and  improve  the  flavor. 

Detection  of  it  as  an  impurity  usually  rests  upon  the  character- 
istic odor  emitted  by  a  small  quantity  when  allowed  to  evaporate 
from  filter  paper. 

Alcohols  in  General. — The  term  alcohol  designates  a  large 
class  of  organic  compounds  which  differ  in  properties  and  appear- 
ance, but  are  alike  in  being  hydroxyl  derivatives  of  saturated 
hydrocarbons.  As  the  radicals  differ  in  their  valence  they  are 
named  according  to  the  number  of  hydroxyl  groups  they  take; 
monohydric  or  monatomic;  dihydric  or  diatomic;  trihydric  or 
triatomic.  The  monohydric  alcohols,  parallel  with  the  methane 
series  and  homologous  with  common  alcohol,  and  having  medical 
importance,  are: 

B.-P.  Sp.  Gr.  at  o°. 

Methyl  alcohol         CH3HO  66°  C.    (150.8°  F.)      0.796. 

Ethyl  "  C2H5HO  78°  C.  (172.4°  F.)  0.806. 

Propyl  "  C3H7HO  97°  C.  (206.6°  F.)  0.817. 

Butyl  "  C4HgHO  117°  C.  (242.6°  F.)  0.823. 

Amyl  "  C5H,,HO  132°  C.  (289.6°  F.)  0.825. 


400  ALIPHATIC    COMPOUNDS 

Three  alcohols  can  be  prepared  from  propane,  C3H8:  mon- 
atomic  propyl  alcohol,  C3H7HO;  diatomic  propylene  alcohol, 
C3H6(HO)2;  and  triatomic  propenyl  alcohol,  C3H5(HO)3.  The 
diatomic  alcohols  are  called  glycols. 

There  may  be  alcohols  with  even  more  hydroxyl  groups,  tetra- 
tomic,  pentatomic,  etc.  Mannitol  is  a  hexatomic  alcohol  with  six 
carbon  atoms,  each  having  a  hydroxyl  group  attached. 

Another  division  is  made  of  alcohols  into  primary,  secondary, 
and  tertiary,  according  as  the  facts  warrant  graphic  formulas  which 
show  that  the  carbon  atom  combined  with  hydroxyl  is  at  the 
same  time  directly  united  with  i,  2,  or  3  other  carbon  atoms. 
Thus,  there  are  three  butyl  alcohols  having  the  formula  C4H9HO. 
There  is  good  reason  for  employing  the  following  graphic  formulas 
to  express  their  differences  in  structure: 

H 


H—  C—  H 

H 

| 

1 

H—  C—  H 

H—  C—  H 

1 

1 

H—  C—  H 

H—  C—  H 

CH3 

| 

1 

H—  C—  H 

H3C—  C—  H 

H3C—  C—  CH3 

I 

I 

1 

HO 

HO 

HO 

Primary  butyl  alcohol. 

Secondary  butyl  alcohol. 

Tertiary  butyl  alcohol. 

(C3H7 .  CH2OH)       (C2H5 .  CH3 .  CHOH)  (CH3 .  CH3 .  CH3 .  COH.) 

A  primary  alcohol  is  one  in  which  the  carbon  atom  in  union 
with  the  hydroxyl  is  directly  united  with  only  i  other  carbon  atom; 
a  secondary  alcohol  is  one  in  which  the  carbon  atom  in  union 
with  the  hydroxyl  is  directly  united  with  2  other  carbon  atoms; 
a  tertiary  alcohol  is  one  in  which  the  carbon  atom  in  union  with  the 
hydroxyl  is  directly  united  with  3  other  carbon  atoms.  There  is 
a  decided  difference  among  these  three  alcohols,  especially  in  their 
behavior  under  the  action  of  oxidizing  agents.  Thus: 

Primary  alcohols  are  converted  first  into  aldehyds,  next  into 
acids  containing  the  same  number  of  carbon  atoms,  and  on  further 
oxidation  break  up  (pp.  406  and  417). 

Secondary  alcohols  are  converted  into  acetones,  which  upon 
further  oxidation  break  up  into  acids  with  a  smaller  number  of 
carbon  atoms  (p.  412). 

Tertiary  alcohols  are  decomposed  without  previous  formation 
of  aldehyds  or  acetones,  yielding  acids  with  a  smaller  number  of 
carbon  atoms. 


ALCOHOLS  401 

DIHYDRIC  ALCOHOLS  OR  GLYCOLS 

The  members  of  this  group  are  called  glycols,  after  the  name 
of  the  simplest  one,  C2H4(OH)2,  ethylene  glycol,  which  corresponds 
with  ethyl  alcohol. 

Ethylene  Glycol.— When  ethylene  bromid,  C2H4Br2,  is  heated 
with  a  dilute  alkali  the  bromin  is  replaced  by  hydroxyl,  and  eth- 
ylene alcohol  is  obtained.  Its  structure  is  indicated  by  this 
equation: 

CH2Br  CH2OH 

|  +      2KOH      =         |  +      2KBr. 

CH2Br  CH2OH 

Properties. — Ethylene  glycol  is  a  thick  colorless  liquid  with  a 
sweetish  taste,  freely  soluble  in  water  and  alcohol.  It  is  a  type 
of  the  class,  all  being  neutral  oily  liquids,  prepared  by  boiling  the 
dibromo-additive  products  of  the  olefins  with  alkalis.  In  compo- 
sition they  have  two  hydroxyl  groups,  thus  differing  from  mono- 
hydric  alcohols  as  calcium  hydroxid,  Ca(OH)2,  differs  from  potas- 
sium hydroxid,  KOH.  With  monobasic  acids  they  form  two 
esters,  neutral  and  alcoholic.  Thus,  mono-acetic  glycol  has  one 
alcoholic  group  left  in  it,  CH2(C2H3O2).  CH2OH,  while  diacetic 
glycol  has  all  the  hydroxyl  replaced  by  the  acid,  CH2(C2H3O2). 
CH2(C2H302). 

Under  the  action  of  oxidizing  agents  one  alcoholic  group 
changes  to  CO  OH,  characteristic  of  acids,  and  an  oxyacid  is 
formed.  If  both  alcoholic  groups  are  oxidized  a  diacid  is  the 
product.  Thus: 

CH2OH  COOH  COOH 

I  I  I 

CH2OH  CH2OH  COOH 

Glycol.  Oxyacetic  acid.  Oxalic  acid. 

TRIHYDRIC    ALCOHOLS 

On  a  preceding  page  it  has  been  stated  that  the  paraffin  pro- 
pane, by  substitution  of  hydroxyl  groups  successively,  can  be 
converted,  first,  into  monohydric  propyl  alcohol,  C3H7OH;  next, 
into  dihydric  propylene  alcohol,  C3H6(OH)2;  and,  last,  to  tri- 
hydric propenyl  alcohol,  C3H5(OH)3.  This  last  named  is  the  only 
trihydric  alcohol  prepared  with  ease  and  which  has  been  well 
studied.  It  is  used  in  medicine  under  the  common  name  of 
glycerin.  The  three  groups  containing  hydroxyl  are  represented 
in  the  formula:  CH2OH,  CHOH,  CH2OH.  The  trihydric  class 
corresponds  to  the  metallic  bases,  like  bismuth  hydroxid,  Bi(OH)3. 

Glycerinum,  U.  S.  P.,  Qlycerol  (C3H5(OH)3)  (Glycerin,  Pro- 
penyl Alcohol,  orGlyceryl  Alcohol). — This  is  obtained  by  the  action 
of  superheated  steam,  by  fermentation,  or  by  saponification  upon 
26 


402  ALIPHATIC    COMPOUNDS 

fats  which  are  not  very  stable  compounds  of  weak  fatty  acids  with 
glycerol,  which  is  weakly  basic. 

C3H5(O.C18H350)3  +  3H20   -    C3H5(OH)3   +   3(C18H35O.OH) 

Tristearin.  Glycerin.  Stearic  acid. 

After  separation  of  the  pasty  mass  of  stearic  acid  the  aqueous 
distillate  is  decolorized  by  charcoal  and  concentrated  by  evapora- 
tion. Redistillation  is  used  to  free  it  from  the  water  which  is 
collected  in  the  first  fractions  condensed. 

Properties.  —  Pure  anhydrous  glycerin  is  a  colorless  crystal,  but 
as  commonly  prepared  contains  some  water,  and  is  then  an  odor- 
less thick  liquid  with  a  specific  gravity  of  1.265  at  15°  C.  (60°  F.). 
It  is  very  hygroscopic,  absorbing  water  from  the  air,  and  is  freely 
miscible  with  water  and  alcohol,  but  not  with  ether  and  chloroform. 
It  is  a  solvent  for  many  solids  and  liquids,  the  official  solutions 
being  called  glycerites,  as  the  glycerite  of  carbolic  acid.  The 
taste  is  sweet,  a  property  common  to  the  glycols  and  other  alcohols 
containing  many  hydroxyl  groups,  such  as  mannitol  and  dulcitol. 
Glycerin  is  an  antiputrescent  and  antiseptic,  but  undergoes  decom- 
position into  acrolein  and  water  under  the  action  of  heat  and 
various  chemicals. 

Tests.  —  Acrolein  Test.  —  Heated  with  sulphuric  acid  it  splits  off 
2  molecules  of  water,  leaving  acrolein,  a  colorless  liquid,  giving 
an  irritating  vapor  with  an  unpleasant  odor  like  burning  grease: 

C3H5(OH)3  C3H40          +          2H20. 

Glycerol.  Acrolein. 

Fehling's  Test.  —  Adulterations  with  glucose  are  detected  by 
Fehling's  test  (see  p.  602).  Pure  glycerin  does  not  respond  to 
this  test  nor  will  it  ferment  with  yeast. 

Borax  Test.  —  Having  fused  borax  in  a  platinum  loop  the  bead 
is  wet  with  glycerin  and  again  heated.  A  green  color  to  the 
flame  shows  that  boric  acid  has  formed  a  volatile  ester  with  the 
glycerin. 

ETHERS   (Simple  and  Mixed) 

In  another  place  reasons  were  given  for  regarding  alcohols  as 
hydroxids  of  hydrocarbon  radicals.  If  hydroxyl  be  considered  as 
derived  from  water  by  the  loss  of  i  atom  of  hydrogen,  then  alco- 
hols, as  hydroxids,  may  be  constructed  on  the  water  plan  by 
replacing  that  atom  of  hydrogen  with  the  radical.  Thus,  water 

being       >O,  ethyl  alcohol  is  C 


By  substituting  another  ethyl  group  for  the  remaining  atom  of 

C*  TT 

hydrogen  in  hydroxyl,  we  get  an  oxid.     Thus,  ^2TT5>O  (p.  372). 

^3  "5 


ETHERS 


403 


This  oxid,  (C2H5)2O,  is  a  substance  long  known  as  ether.  Other 
monovalent  radicals  can  be  linked  by  oxygen  in  the  same  way, 
and  thus  give  rise  to  a  class  of  oxids  or  ethers  named  after  the 
radicals  contained  in  them.  In  the  series  of  simple  ethers,  (CH3)2O, 
is  methyl  ether;  (C2H5)2O  is  ethyl  ether,  the  official  form.  By 
manipulation  at  the  right  moment  the  2  hydrogen  atoms  may 
be  replaced  by  two  different  radicals,  making  a  mixed  ether, 

C*TT 
such  as  r  T|  >O,  methylethyl  ether. 


The  ethers  bear  the  same  relationship  to  the   metallic  oxids 
that  the  alcohols  do  to  the  metallic  hydroxids: 

C2H5  .  OH  corresponds  to  K  .  OH. 

C2H5  .  O  .  C2H5  "  K  .  O  .  K. 

As  ether  contains  no  HO  group  it  is  unaffected  by  potassium  and 
does  not  form  esters  with  weak  acids  like  those  made  by  alcohol. 


FIG.  77. — Apparatus  for  making  and  distilling  ether. 

Ethyl  ether  (C4H10O)  (cether,  sulphuric  ether,  ethyl  oxid) 
is  prepared  by  a  continuous  process  of  distilling  alcohol  with  con- 
centrated sulphuric  acid.  A  flask  having  a  thermometer  and  a 
delivery  tube  connected  with  a  condenser  (Fig.  77)  is  fitted  with 


404  ALIPHATIC    COMPOUNDS 

a  funnel  having  a  stop-cock.  The  funnel  is  charged  with  go-pet 
cent,  alcohol  and  the  tap  closed.  Five  parts  of  alcohol  and  9 
parts  of  sulphuric  acid  are  heated  in  the  flask  to  the  boiling-point, 
140°  C.  (284°  F.).  This  temperature  is  maintained,  for  it  is  the 
point  at  which  ether  distils  over,  and  at  which  alcohol  remains  in 
the  flask.  From  the  funnel  fresh  alcohol  is  slowly  supplied  to 
take  the  place  of  the  ether  which  collects  in  the  receiver.  In  the 
flask  there  accumulates  water  to  dilute  the  sulphuric  acid,  which 
ultimately  becomes  too  weak  to  act.  Up  to  that  limit  the  same 
small  quantity  of  acid  serves  to  convert  a  large  quantity  of  alcohol 
to  ether.  On  comparing  the  molecular  formula  of  ether,  C4H10O, 
with  a  proportional  formula  (2  molecules)  of  alcohol,  2C2H6O  or 
C4H12O2,  it  is  seen  that 

C4H10O  C4H12O2  minus  H2O; 

that  is,  ether  is  the  anhydrid  of  alcohol,  the  elements  of  water 
being  abstracted  by  sulphuric  acid.  The  process  has  two  stages, 
as  shown  in  the  equations: 


C*  "FT 

\SO4      =         lr  5>SO4      +      H2O. 
H^  H   ' 

Alcohol.  Sulphuric  acid.  Ethyl  hydrogen  sulphate. 

+      H2S04. 

If  a  mixture  of  two  alcohols  be  used,  the  distilled  product  will 
consist  of  three  ethers.  Thus,  methyl  and  ethyl  alcohols  yield 
methyl  ether,  ethyl  ether,  and  the  mixed  methylethyl  ether, 
CH3 .  O  .  C2H5. 

Properties. — Ether  is  a  colorless,  neutral,  mobile  liquid  with  a 
characteristic  sweetish  smell.  Its  specific  gravity  is  0.736;  its 
boiling-point  35°  C.  (95°  F.).  The  official  ether  (aether,  U.  S.  P.) 
contains  4  per  cent,  of  alcohol,  which  raises  the  boiling-point. 
Ether  is  highly  volatile  and  inflammable.  Exposed  to  the  air,  an 
explosive  mixture  of  its  vapor  and  air  at  once  forms,  which  renders 
experimentation  with  it  dangerous  and  its  administration  near  an 
open  flame  unsafe.  When  this  exposure  is  unavoidable,  the  light 
should  be  well  above  the  ether,  as  its  vapor,  being  heavier  than  the 
air,  settles  down. 

C4H10O       +       6O2       =       4CO2       +       5H2O. 

Ether.  Air. 

Experiment. — Into  a  slightly  warmed  beaker  put  2  c.c.  of 
ether  and  cover  it  until  the  ether  has  filled  the  beaker  with  vapor. 


ETHERS  405 

Pour  the  heavy  vapor  into  an  empty  beaker  and  prove  its  presence 
by  a  lighted  taper. 

Miscible  in  all  proportions  with  alcohol,  chloroform,  and  other 
organic  liquids,  ether  requires  10  volumes  of  water  to  dissolve  it. 
In  the  arts  it  is  used  as  a  solvent  for  oils,  resins,  alkaloids,  bromin, 
and  iodin.  In  surgery  it  is  used  enormously  as  an  anesthetic, 
the  physiologic  effects  being  those  of  alcohol,  but  the  narcotism 
comes  on  more  promptly  and  is  more  transient.  When  sprayed  on 
the  skin  its  rapid  evaporation  lowers  the  temperature  and  causes  a 
local  numbness.  Spiritus  (ztheris,  U.  S.  P.,  contains  i  part  of  ether 
with  a  little  more  than  2  parts  of  alcohol.  Dose:  i  fl.  dr.  (4  c.c.). 
Spiritus  (Etheris  compositus  (Hoffman's  anodyne)  is  a  mixture  of  i 
part  of  ether  and  2  parts  of  alcohol  with  2.5  per  cent,  of  ethereal 
oil.  Dose:  5  to  60  tit  (0.33-4  c.c.). 

Toxicology. — As  an  anesthetic,  ether  is  safer  than  chloroform, 
the  record  justifying  expectation  of  i  death  in  12,000  etherizations. 
It  is  sometimes  used  for  suicidal  purposes  and  as  a  habitual 
intoxicant. 

Symptoms. — When  inhaled,  the  vapors  irritate  the  larynx  and 
increase  the  flow  of  saliva  and  mucus.  Unconsciousness  comes 
on  soon,  the  pulse  and  breathing  becoming  slow  and  irregular. 
An  overdose  may  cause  death  by  asphyxia.  Notably  dangerous 
is  the  sequel,  in  the  shape  of  pneumonia  from  pulmonary  irrita- 
tion. When  taken  by  the  stomach,  ether  causes  a  sense  of  local 
irritation  in  stomach  and  bowels,  and  symptoms  of  general  intoxi- 
cation come  on  quickly. 

Fatal  Dose. — By  inhalation  death  has  followed  2^  fl.  oz.  (75 
c.c.).  Continuous  inhalation  of  air  containing  6  per  cent,  of  ether 
vapor  arrested  respiration  in  ten  minutes.  Anesthesia  may  be 
induced  with  about  half  that  concentration  in  the  same  period  of 
time. 

Fatal  Period. — Failure  of  respiration  may  occur  before  or 
after  full  unconsciousness.  The  pulmonary  and  renal  sequels 
may  cause  death  days  after  recovery  from  the  narcotism. 

Treatment. — The  immediate  indication  is  for  fresh  air  and  res- 
piratory stimulants,  such  as  ammonia,  artificial  respiration,  oxygen, 
and  hypodermic  doses  of  strychnin. 

Detection. — If  not  identified  by  odor  or  information  from  the 
surroundings,  the  detection  is  most  difficult,  as  the  ether  quickly 
escapes  from  the  body  by  its  vaporization.  A  few  drops  may  be 
recovered  by  distillation  at  a  low  heat  and  condensation  in  re- 
ceivers surrounded  by  a  mixture  of  salt  and  ice.  The  distillate 
will  have  the  ethereal  odor,  will  burn  quickly,  evaporate,  and  its 
vapor  will  turn  to  green  the  yellow  spot  made  on  filter  paper  with 
potassium  bichromate  and  sulphuric  acid. 


406  ALIPHATIC    COMPOUNDS 

ALDEHYDS 

These  compounds  are  the  first  stage  in  the  process  of  oxida- 
tion of  alcohols,  the  next  products  being  the  acids.  As  the  first 
effect  of  oxidizing  an  alcohol  is  the  abstraction  of  2  atoms  of 
hydrogen  to  form  water,  the  resulting  compound  is  named  by 
blending  significant  syllables  from  the  phrase  "alcohol  dehydroge- 
natum." 

CH40  +          O  CH20  +          H20. 

Methyl  alcohol.  Formaldehyd. 

C2H6O          +          O  C2H4O          +          H2O. 

Ethyl  alcohol.  Acetaldehyd. 

The  structural  changes  are  represented  by  graphic  equations 
thus: 

H  H 

(i)  H  —  C  —  0-j-H     H-    O        =        H  —  C  =  0     4-     H2O. 

ri  ..... 

Methyl  alcohol.  Formaldehyd. 

H  O.H 

(ii)  H  —  C-0    +    O        =        H  —  C  =  0. 

Formaldehyd.  Formic  acid. 

Structure.  —  With  phosphorus  pentachlorid  the  aldehyds  yield 
phosphoric  oxychlorid  and  ethyledene  chlorid,  thus: 

C2H40      +      PC15      -      POC13      +      C2H4C12. 

Ethyl  aldehyd. 

The  atom  of  oxygen  alone  is  replaced  by  2  of  chlorin,  which 
would  not  happen  if  the  oxygen  were  in  a  hydroxyl  group,  but  is 
possible  if  the  oxygen  be  in  carbonyl,  CO,  where  it  is  in  com- 
bination with  carbon  by  both  affinities,  C=O.  The  simplest 
aldehyd  is  formic  aldehyd,  CH2O,  and  there  is  but  one  way  of 

/TT 

expressing  its  constitution  graphically:  H—  C^~-      The  peculiar 


/TT 

properties   of  aldehyds   are   due    to    the   group    —  C-     Acetic 


/TT 

aldehyd  then  becomes  CH3  —  C^     •     Under  certain  conditions  for- 

maldehyd  forms  additive  compounds  as  if  it  were  not  wholly  sat- 
urated: its   valence   at   such   times   is   expressed   by   the   graphic 

formula  H- 


ALDEHYDS  407 

Formaldehyd,  H  .  COH  or  CH2O,  can  be  formed  by  oxidizing 
methyl  alcohol  vapor,  through  the  catalytic  agency  of  incan- 
descent platinum.  This  reaction  is  much  accelerated  when 
the  platinum  is  finely  divided,  as  spongy  platinum.  When  cal- 
cium formate  is  heated  formaldehyd  comes  off  as  a  vapor: 

Ca(H.CO2)2  CaCO3          +          H .  COH. 

It  is  a  colorless  gas  with  a  strong  pungent  odor,  and  condenses 
at  -21°  C.  (-5.8°  F.)  to  a  colorless  liquid.  It  is  readily  soluble 
in  water,  making  a  colorless  volatile  liquid  which  is  a  convenient 
preparation  for  medicinal  use.  The  4o-per  cent,  aqueous  solution 
is  called  liquor  jormaldehydi,  U.  S.  P.,  and  sometimes  formalin.  By 
heat  it  evolves  the  gas  with  some  steam.  It  is  of  great  value  in 
hardening  and  preserving  anatomic  specimens  and  as  a  germicide, 
antiseptic,  and  deodorizer.  The  aldehyds  are  unstable,  and  not 
being  saturated  compounds  they  readily  join  to  other  elements  or 
groups.  Intermediate  between  alcohols  and  acids,  they  take  oxy- 
gen to  form  the  latter  or  take  hydrogen  to  make  the  former.  Thus: 

CH2O  +  O  =  CH2O2  (Formic  acid). 

CH2O  +  H2  CH4O  (Methyl  alcohol). 

CH2O  -f  NH3  :    :  CH3ONH2  (Aldehyd  ammonia). 

CH20  +  H2S  =  H20  +  CH2S  (Sulphaldehyd). 

Like  other  lower  aldehyds  it  forms  an  additive  compound  with 
sodium  bisulphite  which  is  soluble. 

For  disinfecting  a  closed  room  the  liquor  jormaldehydi  may 
be  vaporized  by  heat  or  sprayed.  The  vapor  combines  directly 
with  the  albumin  of  the  bacterial  cell  and  destroys  its  reproductive 
powers.  An  approved  method  known  as  permanganate  formalin 
depends  upon  the  fact  that  potassium  permanganate  oxidizes  a 
portion  of  the  formaldehyd  to  formic  acid,  liberating  enough 
heat  to  evaporate  the  remainder.  A  deep  tin  pail  is  warmed 
and  then  receives  the  permanganate  as  crystals  or  powder,  8J  oz. 
for  every  1000  cu.  ft.  of  room  space.  Upon  this  20  fl.  oz.  of  for- 
malin is  poured.  Effervescence  begins  at  once,  the  room  is  closed, 
and  the  operation  is  over  in  five  or  ten  minutes  without  the  use  of 
a  lamp.  After  twelve  hours  the  room  is  opened  and  the  odor 
removed  by  sprinkling  ammonia. 

Paraformaldehyd  [(CH2O)J  (Tri-oxymethylene).— When  for- 
maldehyd is  evaporated  or  when  moderately  heated,  2  or  more 
molecules  join  to  make  a  polymeric  modification.  This  is  a  color- 
less, amorphous  solid,  melting  at  171°  C.  (339°  F.),  subliming 
at  a  slightly  higher  temperature,  and  when  strongly  heated  breaking 


408  ALIPHATIC    COMPOUNDS 

up  into  gaseous  formaldehyd.  As  the  gas  cools  paraformaldehyd 
is  again  obtained.  The  formation  of  the  gas  may  be  shown  by 
Schiff's  reaction,  using  paper  wet  with  decolorized  fuchsin  (see 
Tests). 

Polymerism  is  the  condition  of  a  substance  where  the  molecules 
in  their  original  proportion  are  aggregated  into  a  more  complex 
group.  The  different  modifications  are  similar  to  the  allotropic 
forms  of  elements,  and  their  relationship  to  one  another  resembles 
that  of  yellow  and  red  phosphorus.  The  constitution  of  the 
polymer  of  formaldehyd,  (CH2O)3,  is  usually  represented  by  the 
graphic  formula  below,  the  dotted  lines  showing  the  method  of 
union: 


H— H 


Toxicology  of  Formaldehyd.— In  spite  of  its  reputation  as 
a  disinfectant  harmless  to  man,  there  are  many  instances  of  inflam- 
mation of  the  conjunctiva  and  air-passages  among  those  who  manu- 
facture formaldehyd,  or  who  breathe  its  vapor  when  disinfecting 
houses.  The  higher  animals  are  injured,  if  not  killed,  by  the  vapor 
when  it  is  present  in  sufficient  strength  to  destroy  infectious  germs. 
Under  the  names  preservalene  and  jreezene  it  is  widely  used  by 
dairymen  to  preserve  milk  in  hot  weather.  In  any  but  the  smallest 
amounts  it  inhibits  the  action  of  the  digestive  ferments  and  causes 
indigestion  and  imperfect  assimilation.  Very  small  amounts  suf- 
fice to  preserve  milk  for  several  days  with  very  little  retarding 
effect  on  digestion,  but  the  mixture  should  be  labeled  preserved. 
(See  Milk,  p.  568.) 

Symptoms. — Solutions  containing  i  part  in  2000  irritate  the 
skin,  causing  eczema,  ulcerations,  and  even  gangrene.  When  the 
40  per  cent,  liquid  is  taken  in  doses  of  J  oz.  or  more,  the  symp- 
toms are  pain  in  the  mouth  and  abdomen,  vomiting,  giddiness, 
diarrhea  with  straining,  urinary  suppression,  and  recovery  or, 
may  be,  death  by  dyspnea  and  syncope. 

Treatment. — After  evacuating  the  stomach  dilute  spirits  of 
ammonia  will  be  of  help.  The  odor  of  its  vapor  in  a  room  is  at 
once  removed  by  ammonia  vapor. 

Test. — For  detection  of  the  presence  of  formaldehyd  in  milk 
see  p.  569.  When  in  a  solid  form,  the  material,  minced,  is  digested 
for  an  hour  at  80°  C.  (176°  F.)  in  water  acidified  with  sulphuric 


ALDEHYDS  409 

acid.  Dry  powdered  sodium  sulphate  in  excess  is  added,  and  the 
paste  distilled.  If  the  first  portions  of  the  distillate  contain  for- 
maldehyd,  it  will  respond  to  the  following  tests: 

Schiffs  Fuchsin  Reaction.  —  Dissolve  0.2  gm.  of  rosanilin  or 
the  hydrochlorid  in  10  c.c.  of  a  freshly  prepared,  saturated  aqueous 
solution  of  sulphur  dioxid.  Allow  the  solution  to  stand  until  all 
signs  of  pink  disappear  and  it  becomes  colorless  or  pale  yellow. 
Then  dilute  with  water  to  200  c.c.  and  preserve  for  use  in  a  tightly 
stoppered  bottle.  It  turns  pink  or  violet  with  formaldehyd. 

With  light  excluded,  the  reagent  keeps  well.  If  necessary  its 
sensitiveness  may  be  restored  by  addition  of  sodium  acetate  till  a 
pink  color  appears,  which  is  discharged  by  a  few  drops  of  the 
original  reagent.  Not  only  do  aldehyds  redden  it,  but  also  alkaline 
solutions,  heat,  or  prolonged  exposure  to  the  air. 

When  the  formaldehyd  is  in  a  gaseous  state,  the  test  may  be 
applied  by  hanging  in  the  air  filter-paper  wet  with  the  reagent. 

Resorcin  Test.  —  Having  made  a  solution  of  5  parts  of  resor- 
cin  in  100  of  potassium  hydroxid  (40  per  cent.),  a  portion  is 
heated  with  an  equal  volume  of  formaldehyd,  and  a  red  color  is 
obtained. 

Acetaldehyd  (CH3.COH)  (Acetic  Aldehyd).—  This  is  formed 
by  the  oxidation  of  ethyl  alcohol  in  the  operation  of  distilling  a 
mixture  of  alcohol,  manganese  dioxid,  and  sulphuric  acid.  The 
distillate  is  a  mixture  which  is  redistilled  below  50°  C.  (122°  F.). 
The  second  distillate  is  mixed  with  ether  and  saturated  with  am- 
monia to  get  a  crystalline  precipitate  of  aldehyd  ammonia.  This 
substance,  distilled  with  dilute  sulphuric  acid  at  a  low  temperature, 
yields  a  dilute  aldehyd.  The  water  is  removed  with  calcium 
chlorid.  Acetic  aldehyd  is  a  colorless,  volatile,  inflammable  liquid, 
boiling  at  20.8°  C.  (69°  F.).  Its  odor  is  suffocating,  like  that  of 
sulphur  dioxid.  It  is  soluble  in  water,  alcohol,  and  ether,  and 
acts  as  a  reducing  agent  on  ammoniacal  solutions  of  silver. 

The  formation  of  aldehyd  from  ethyl  alcohol  by  abstracting 
H2  is  shown  in  equation  (i);  in  equation  (2)  is  shown  how  acetic 
acid  is  formed  by  oxidation  of  the  aldehyd: 

H    H  H    H 

!)  H—  C—  C-O-I-H     +     0         =        H—  C—  C  =  0     +    H2O 


(!) 


Ethyl  alcohol.  Acetaldehyd. 


H    H  H    O.H 

(2)  H—  C—  C-O  -f      O          =         H—  C—  C  = 
H  H 

Acetaldehyd.  Acetic  acid. 


410  ALIPHATIC    COMPOUNDS 

Acetic  aldehyd  is  a  rapid  intoxicant,  inducing  profound  stupor 
and  deleterious  after-effects,  such  as  attend  the  drinking  of  high 
wines — raw  spirits  which  have  not  been  deprived  of  it,  as  they 
should,  before  being  taken  internally. 

Three  polymerids  of  aldehyd  are  known:  aldol,  (C2H4O)2; 
paraldehyd,  (C2H4O)3;  and  metaldehyd,  (C2H4O)n. 

Paraldehyd  is  formed  when  a  drop  of  sulphuric  acid  is  added  to 
aldehyd.  There  is  violent  action  and  a  change  to  a  more  pleasant- 
smelling  liquid  with  a  burning  taste,  boiling  at  124°  C.  (255°  F.) 
and  solidifying  by  cold.  It  is  soluble  in  water,  and  if  distilled  with 
dilute  sulphuric  acid  goes  back  to  aldehyd. 

Toxicology. — Its  physiologic  effects  in  doses  of  30  to  60  min. 
(2-4  c.c.)  are  those  of  a  soporific  like  chloral,  but  with  less  depres- 
sion of  the  heart.  It  gives  a  strong  disagreeable  odor  to  the 
breath  and  the  urine.  A  very  large  amount,  such  as  3  fl.  oz. 
(90  c.c.),  will  cause  nausea,  vomiting,  vertigo,  headache,  ending  in 
profound  stupor.  Habitual  use  of  it  in  doses  of  2  oz.  (60  c.c.) 
leads  to  a  deplorable  condition,  characterized  by  mental  weakness, 
dyspepsia,  sleeplessness,  and  delusions. 

Treatment. — The  indications  are  the  same  as  in  poisoning  from 
chloral. 

Detection. — Paraldehyd  does  not  give  the  reactions  nor  show 
the  ordinary  properties  of  aldehyd.  It  must  first  be  converted  to 
aldehyd  by  distilling  with  steam,  the  suspected  material  having 
been  first  acidified  by  sulphuric  acid.  The  distillate  should  give 
Schiff's  reaction  with  fuchsin  (see  Formaldehyd,  p.  407). 

Tollen's  Test. — A  deposit  occurs  of  a  silver  mirror  on  the  glass 
of  a  test-tube  that  has  been  cleaned  with  hot  caustic  soda  and 
washed  with  distilled  water,  when  weak  aldehyd  is  added  to  am- 
moniacal  solution  of  silver  oxid: 

CH3 .  COH    +    Ag2O    =    CH3CO .  OH    +    2Ag. 

This  is  a  very  sensitive  test.  The  reagent  is  made  by  dissolving 
3  gm.  of  silver  nitrate  in  30  gm.  of  25  per  cent,  ammonia  water 
and  adding  3  gm.  of  sodium  hydroxid  dissolved  in  3  c.c.  of  water. 

Chloral  (CC13 .  COH)  (Trichloraldekyd).—'This  most  important 
derivative  of  acetic  aldehyd  is  prepared  by  saturating  absolute 
alcohol  with  dry  chlorin.  The  first  product  is  a  crystalline  sub- 
stance which  is  shaken  with  sulphuric  acid  and  distilled.  The 
distillate  treated  with  lime  and  again  distilled  yields  chloral.  The 
syllable  -al  used  as  a  suffix  indicates  an  aldehyd.  Thus  acetic 
aldehyd  is  sometimes  called  ethanal,  to  indicate  that  it  is  the  alde- 
hyd formed  from  ethanol  (ethyl  alcohol).  Chloral  is  an  abbrevia- 
tion for  chlorethanal.  The  first  effect  of  chlorin  is  to  convert  the 


ALDEHYDS  41 1 

alcohol  to  aldehyd  by  extracting  two  hydrogen  atoms  to   make 
2HC1;  the  second  is  to  chlorinate  the  aldehyd: 

CH3COH    +    3C12    =     CC13COH     +     3HC1. 

Aldehyd.  Choral. 

Chloral  is  a  colorless  oily  liquid  with  a  pungent  odor  and  acrid 
taste.  Its  reactions  show  it  to  be  an  aldehyd  in  its  chemical 
properties.  It  is  soluble  in  water,  and  in  a  small  amount  of  the 
solvent  it  forms  a  colorless  crystalline  compound,  chloral  hydrate, 
CC13COH .  H20. 

On  heating  with  an  alkali,  chloral  yields  chloroform  and  a 
formate: 

CC13COH       +       KOH       =       CHC13       +       H.COOK 

Chloral.  Chloroform.  Potassium  formate. 

Chloralum  hydratum  (U.  S.  P.)  occurs  as  volatile  crystals 
having  a  odor  like  .that  of  a  melon  and  a  taste  the  unpleasant 
nature  of  which  is 'masked  by  solution  in  beer,  whisky,  or  wine. 
It  is  soluble  in  water,  alcohol,  and  ether.  Dose:  10  to  25  gr. 
(0.66-1.62  gm.).  It  is  incompatible  chemically  with  alcohol,  potas- 
sium iodid,  carbolic  acid,  and  camphor. 

Toxicology. — Acute  poisoning  occurs  from  accidental  over- 
dosing, also  from  criminally  mixing  it  with  the  drink  of  a  victim, 
when  it  is  known  as  knock-out  drops.  At  no  stage  does  it  exhila- 
rate like  alcohol,  nor  does  it  relieve  pain  like  chloroform  until  a  full 
hypnotic  dose  has  caused  sleep.  With  massive  doses  the  soporific 
effects  are  much  like  those  of  heavy  doses  of  alcohol  or  chloroform. 
The  skin  is  cold  and  clammy;  the  brain  and  spinal  centers  are 
depressed  and  finally  paralyzed.  As  a  gastric  irritant  it  may  first 
cause  nausea  and  vomiting,  but  deep  coma  soon  sets  in  with 
thready  pulse  and  feeble  respiration,  growing  more  shallow  and 
irregular  until  it  ceases  altogether.  .Chronic  poisoning  is  quite 
common,  the  habit  of  chloral  tippling  being  formed  to  cure  insom- 
nia. In  time  varied  symptoms  are  produced,  such  as  indigestion, 
wasting,  skin  eruptions,  conjunctivitis,  pains,  wakefulness,  ner- 
vous depression  with  melancholia,  and  death  from  heart  failure. 

Dose. — The  maximum  safe  dose  is  20  gr.  (1.29  gm.),  repeated 
twice  at  intervals  of  an  hour. 

Postmortem  Appearances. — Characteristic  changes  are  not  found 
at  the  autopsy. 

Treatment. — The  stomach  should  be  promptly  evacuated  and 
washed  out  with  warm  alkaline  water.  If  no  tube  be  at  hand, 
then  apomorphin,  in  hypodermic  doses  of  5  min.  of  a  2  per  cent, 
solution,  or  other  emetics,  may  be  used.  To  rouse  the  heart 


412  ALIPHATIC    COMPOUNDS 

strong  coffee  may  be  given  by  mouth  or  rectum,  and  hypodermic 
injections  of  2  or  3  min.  of  a  2  per  cent,  solution  of  strychnin 
nitrate.  Applications  of  hot  bottles  and  blankets,  flicking  the  face 
with  a  wet  towel,  artificial  respiration,  and  oxygen,  are  measures 
that  may  prove  of  service  to  combat  the  depression. 

Fatal  Dose. — Three  grains  have  proved  fatal  to  a  child  one 
year  old.  Ten  grains  have  proved  fatal  to  a  woman  of  seventy 
with  a  weak  heart.  On  the  other  hand,  recovery  has  followed 
doses  of  more  than  half  an  ounce. 

Tests. — In  the  urine  some  chloral  is  eliminated  unchanged,  but 
most  of  it  forms  a  compound  with  glycuronic  acid  called  uro- 
chloralic  acid,  which  may  be  mistaken  for  glucose,  as  it  reduces 
the  copper  sulphate  of  Fehling's  solution.  As  urochloralic  acid 
and  its  salts  are  levorotatory  to  polarized  light,  by  means  of  the 
polariscope  we  can  distinguish  between  " chloral  urine"  and 
"  sugar  urine,"  which  is  dextrorotatory.  If  the  urine  be  acidified 
with  sulphuric  acid  and  shaken  with  ether  in  a  separating  funnel, 
the  ether  takes  up  the  chloral  and  on  evaporation  leaves  it  as  a 
solid  residue.  The  contents  of  the  stomach  should  be  digested 
for  twenty-four  hours  with  four  volumes  of  absolute  alcohol 
acidified  with  sulphuric  acid;  then  filtered  and  evaporated.  Petro- 
leum ether  will  remove  fat  and  sulphuric  ether  will  extract  the 
chloral. 

Tests  may  be  applied  to  the  ethereal  residue.  Strong  alkalis 
warmed  convert  chloral  to.  chloroform,  yielding  the  familiar  odor 
of  that  substance.  The  chloroform  may  be  identified  by  the 
Ragsky  process,  the  betanaphthol  test,  and  the  offensive  isobenzo- 
nitril  test  (pp.  388,  389). 

Chloral,  having  in  it  the  group  COH,  like  other  aldehyds, 
reduces  Fehling's  solution  (p.  602). 

To  determine  the  quantity  of  chloral  dissolved  magnesia  is 
first  used  to  neutralize  acids,  and  a  measured  amount  of  normal 
solution  of  sodium  hydroxid  is  added  to  render  the  solution  dis- 
tinctly alkaline.  The  excess  is  estimated  by  a  normal  oxalic-acid 
solution,  and,  subtracted  from  the  original  amount,  gives  the  pro- 
portion taken  up  by  the  chloral.  For  i  c.c.  of  normal  sodium 
hydroxid  that  has  united  with  the  chloral  calculate  0.1655  gm.  of 
chloral. 

KETONES    (Acetones) 

The  interesting  substance  called  acetone,  or  dimethyl  ketone, 
CH3 .  CO  .  CH3,  belongs  to  a  class  of  compounds  produced  by 
the  incomplete  oxidation  of  secondary  alcohols  (p.  400).  If  sec- 
ondary propyl  alcohol  be  oxidized,  2  atoms  of  hydrogen  are  ab- 
stracted, just  as  when  a  primary  alcohol  is  so  treated.  But  the 


KETONES  413 

primary  alcohol  forms  an  aldehyd,   while  the  secondary  alcohol 
forms  a  ketone.     Thus: 

+      O  CH3>CO     +     H'°' 

Secondary  propyl  Acetone. 

alcohol. 

All  ketones  are  regarded  as  containing  divalent  carbonyl,  ZZCO, 
linking  together  2  hydrocarbon  radicals.  A  mixed  ketone  is  one 
which  contains  2  different  radicals,  as  methylethyl  ketone,  CH3. 
CO  .  C2H5.  Both  ketones  and  aldehyds  may  be  regarded  as 
derived  from  the  paraffins  by  substituting  i  atom  of  oxygen  for 
2  atoms  of  hydrogen;  they  are,  therefore,  isomeric.  Thus,  C3H6O 
is  the  empiric  formula  for  acetone,  CH3  .  CO  .  CH3,  and  also  for 
propaldehyd,  CH3  .  CH2  .  COH.  The  difference  of  constitution 
is  shown  by  the  further  action  of  oxygen,  which  causes  a  ketone 
to  break  up  into  a  mixture  of  two  or  more  acids,  but  unites  with 
an  aldehyd  to  make  a  single  corresponding  fatty  acid.  They 
have,  however,  many  resemblances  in  chemical  behavior,  such  as 
the  similar  reaction  with  phosphorus  pentachlorid,  explicable  from 
the  fact  that  both  contain  the  carbonyl  group  (p.  406): 


Acetone,  ;;;:3>c=o-     Aldehyd,          >C=O. 


Ketones  are  more  stable  than  aldehyds,  as  they  have  no  avail- 
able hydrogen  left  for  oxidation;  they  do  not  reduce  alkaline 
solutions  of  copper  and  other  metallic  salts,  nor  do  they  combine 
directly  with  alcohols  or  with  ammonia.  They  do  not  polymerize, 
as  do  the  aldehyds.  Their  names  always  have  the  suffix  -one, 

Acetone  is  the  most  important  ketone.  It  can  be  prepared 
by  the  dry  distillation  of  sugar,  tartaric  acid,  or  the  acetates: 

Ca(CH3CO2)2  (CH3)2CO         +         CaCO3. 

Calcium  acetate.  Acetone. 

It  is  a  mobile,  colorless  liquid,  with  a  pleasant  ethereal  odor,  spe- 
cific gravity  0.792.  It  boils  at  56°  C.  (132.8°  F.),  is  miscible  with 
water,  alcohol,  and  ether.  It  dissolves  fats,  resins,  and  guncotton. 
In  diabetes  and  some  other  diseased  states  it  exists  in  the  blood 
and  urine,  and  its  peculiar  odor  may  be  detected  on  the  breath. 
With  its  congeners,  diacetic  acid  and  oxybutyric  acid,  it  is  prob- 
ably due  to  faulty  fat-metabolism  and  contributes  to  bring  on  the 
symptoms  of  diabetic  coma. 

Tests  for  Acetonuria.  —  (i)  Distil  25  c.c.  from  500  c.c.  of  urine, 
which  has  been  acidulated  with  phosphoric  acid  to  prevent  frothing, 


414  ALIPHATIC    COMPOUNDS       • 

and  apply  the  iodoform  test  by  adding  a  small  quantity  of  iodin 
and  dropping  in  potassium  hydroxid  until  the  iodin  color  disap- 
pears. The  odor  of  iodoform  is  recognized,  and  soon  a  yellow 
crystalline  precipitate  appears. 

(2)  Without  distilling,  add  to  the. urine  an  excess  of  a  solution 
of  5  gm.  of  fresh  mercuric  oxid  in  100  c.c.  of  2  per  cent,  sulphuric 
acid.  By  filtration  remove  the  precipitate  and  boil  the  filtrate  for 
several  minutes.  A  white  precipitate  or  even  a  cloudy  appearance 
denotes  acetone. 


SULPHUR  DERIVATIVES  OF  THE  PARAFFINS 

NOT  only  does  sulphur  form  a  series  of  mineral  compounds 
parallel  with  those  of  oxygen,  but  also  a  class  corresponding  to 
the  simple  ethers,  alcohols,  aldehyds,  acids,  and  ketones,  which 
are  oxygen  derivatives  of  the  paraffins.  These  are  named  from 
theion  (sulphur)  as  //w'0-alcohols,  //^'0-ethers,  //^Valdehyds,  thio- 
acids,  //^o-ketones.  In  addition,  sulphur  forms  compounds  which 
have  no  oxygen  counterpart,  such  as  the  sulphoxids,  sulphones, 
and  sulphonic  acids.  Two  classes  of  compounds  are  formed  by 
the  action  of  hydrogen  sulphid  upon  the  alcohols — namely,  hydro- 
sulphids  and  sulphids.  The  relationship  of  these  to  alcohols  and 
ethers  is  shown  by  the  formulas: 

Ethyl  alcohol  or  hydroxid C2H6 .  OH. 

Ethyl  thio-alcohol  or  hydrosulphid C2H5 .  SH. 

Ethyl  ether  or  oxid (C2H5)2O. 

Ethyl  thio-ether  or  sulphid (C2H5)2S. 

The  thio-alcohols  or  organic  hydrosulphids  have  been  long 
known  as  mercaptans  (mercurium  captans)  because  they  readily 
seize  on  mercuric  oxid  to  form  crystalline  compounds,  called 
mercaptids  or  thio-ethylates: 

2C2H5.SH     +      HgO     =      (C2H5.S)2Hg     +      H2O. 

Ethyl  mercaptan.  Mercuric  mercaptid. 

Ethyl  Mercaptan  (C2H5.SH)  (Thio-alcohol').— This  substance 
has  become  important  as  the  material  from  which  the  drug  sul- 
phonal  is  made.  It  is  prepared  by  the  action  of  ethyl  chlorid  on 
potassium  hydrosulphid: 

C2H5C1       +       KHS       =       C2H5.SH       +       KC1. 


SULPHUR    DERIVATIVES    OF    THE    PARAFFINS  415 

It  is  a  colorless  neutral  liquid,  with  an  unpleasant  odor,  like 
that  of  garlic.  It  boils  at  36.2°  C.  (97.2°  F.).  Other  mercaptans 
are  obtained  by  similar  reactions.  They  all  have  disagreeable 
odors,  and  in  chemical  properties  resemble  ethyl  mercaptan. 

Thio-ethers  or  sulphids,  like  ethyl  sulphid  (C2H5)2S,  are  made 
by  distilling  salts  of  ethyl  sulphuric  acid  with  potassium  sulphid: 

2C2H5.KSO4     +      K2S     =      (C2H5)2S     +      2K2SO4. 

Ethyl  potassium  sulphate.  Ethyl  sulphid. 

Sulphonic  acids  are  acids  containing  the  group  SO2  .  OH 
attached  to  a  hydrocarbon  radical  by  the  sulphur  atom  and  not 
by  the  oxygen,  as  in  sulphites,  thus: 

O  /OC2H5 

O  S^O 

\OH  \OC2H5 

Ethyl  sulphonic  acid.  Ethyl  sulphite. 

They  are  obtained  by  oxidation  of  mercaptans  with  nitric  acid: 
C2H5.SH       +       3O  C2H5.SO2.OH 

Ethyl  mercaptans.  Ethyl  sulphonic  acid. 

They  are  strong  acids,  which  unite  with  metals  instead  of  the 
hydrogen  of  hydroxyl,  forming  salts  like  potassium  ethyl  sulpho- 
nate,  C2H5  .  SO2  .  OK. 

Mercaptols  (thioketones)  are  formed  by  the  union  of  ketones 
and  mercaptans: 


|      C2H5  .  SH  CH3^p^C2H5S      , 

C2H6  .  SH  CH,^    ^C2H5S 

Acetone.  Ethyl  mercaptan.  Ethyl  mercaptol. 

When  a  mercaptol  is  oxidized  the  product  is  a  sulphone,  such 
as  sulphonmethane  "sulphonal"  and  sulphonethylmethane  "trional." 

Sulphonmethanum  (Diethylsulphone-dimethylmethane).  —  This 
is  formed  by  oxidizing  ethyl  mercaptol  with  potassium  permanga- 
nate: 


^p^as        \      Ar\        .          3^   p^252 
CH3>(  <C2H6S  CH3>(  <C2H5S02 

Ethyl  mercaptol.  Sulphonal. 

It  is  obtained  in  colorless,  tasteless  prismatic  crystals,  sparingly 
soluble  in  cold  water  or  cold  alcohol,  but  quite  soluble  in  hot 
water  or  hot  alcohol.  It  is  used  as  a  hypnotic,  having  the  same 
properties  as  paraldehyd,  though  more  uncertain  because  of  its 
insolubility  in  water.  Dose:  20  to  40  gr.  (1.25-2.50  gm.). 

Toxicology.  —  The  symptoms  due  to  excessive  doses  are:  Stupor, 
insensibility,  sometimes  preceded  by  convulsions;  the  breathing 


416  ALIPHATIC    COMPOUNDS 

is  irregular,  pulse  weak,  and  skin  cyanotic.  Death  may  be  due  to 
failure  of  respiration  or  to  suppression  of  urine.  In  lingering  cases 
the  urine  is  red  from  the  hematoporphyrin  of  dissolved  blood. 
The  sulphonal  habit  has  caused  this  symptom  with  albuminuria, 
eruptions,  and  impairment  of  mind  and  locomotion.  Chronic 
poisoning  from  long-continued  small  doses  is  attributable  to  the 
slow  elimination  by  the  kidney,  causing  a  cumulative  action. 

Fatal  Dose  and  Period. — Death  has  been  caused  by  30  gr. 
(1.94  gm.),  yet  recovery  after  ninety  hours  of  sleep  has  followed 
a  dose  of  3  oz.  (93  gm.).  A  fatal  result  in  a  few  hours  or  days 
would  probably  follow  75  gr.  (4.85  gm.). 

Treatment. — The  stomach  should  be  evacuated  with  a  siphon 
tube,  using  hot  water,  and  the  intestines  emptied  with  purgatives. 
Hypodermic  injections  of  strychnin  are  useful  to  sustain  the 
heart  and  respiration. 

Detection. — Owing  to  its  remarkable  stability,  urinary  or  post- 
mortem isolation  is  not  difficult.  It  is  accomplished  by  making 
an  alcoholic  extract  of  the  material,  evaporating,  extracting  the 
residue  with  hot  water,  evaporating,  and  finally  extracting  the 
residue  with  ether.  The  tests  are  applied  to  the  residue  of  this 
last  extraction. 

Test. — Mixed  with  powdered  charcoal  and  heated  in  a  test- 
tube,  sulphonal  is  reduced  and  breaks  up  into  mercaptan  (detected 
by  garlicky  odor);  formic  and  acetic  acids  (the  vapor  reddens 
litmus  paper),  and  sulphur  dioxid  (which  bleaches  paper  wet  with 
blue-starch  iodid). 

Trional,  Sulphonethylmethanum,  U.  S.  P.  (Diethylsulphone- 
methylethyl methane). — This  syllable  tri-  is  used  because  there  are 
three  ethyl  groups  in  the  compound,  while  sulphonal  has  only  two: 

)2.C2H5 


It  is  a  white  powder  with  a  faint,  bitter  taste.  It  is  sparingly 
soluble  in  water,  and  resembles  sulphonal  in  its  effects,  but  is  more 
hypnotic.  Dose:  7  to  30  gr.  (0.5-2  gm.).  It  has  caused  death 
with  symptoms  like  those  of  sulphonal. 

Tetronal  (Diethylsulphone-diethylmethane).  —  In  this  sulphonal 
compound  there  are  four  ethyl  groups,  each  addition  of  ethyl 
increasing  the  hypnotic  power: 

-j  .  C2H5 


It  is  used  like  sulphonal.     Dose:  7  to  30  gr.  (0.5-2  gm.). 

It  is  a  narcotic  poison  with  symptoms  like  those  of  sulphonal. 


FATTY    ACIDS 


417 


FATTY  ACIDS 

THE  relationship  of  the  fatty  acids  to  other  oxygen  derivatives 
of  the  paraffins  is  shown  in  the  structural  formula  of  the  second 
member: 

C2H6         C2H5.HO         CH3.COH         CH3 .  COOH 

Ethane.  Ethyl  alcohol.        •        Acetic  aldehyd.  Acetic  acid. 

In  another  place  (p.  409)  are  the  equations  for  the  stages  of 
oxidation  from  an  alcohol  to  an  acid  by  way  of  an  aldehyd.  The 
aldehyd  group,  — COH,  receiving  an  addition  of  oxygen,  be- 
comes — COOH,  carboxyl,  and  the  reactions  of  the  substance 
change  from  those  of  an  aldehyd  to  those  of  an  acid.  As  the 
higher  members  of  the  acid  series  are  components  of  animal  and 
vegetable  fats,  the  entire  class  is  called  fatty,  or  aliphatic. 

The  first  acid,  formic,  H  .  COOH,  has  an  atom  of  hydrogen 
which  does  not  ionize  joined  to  the  carboxyl,  which  contains 
another  atom  of  hydrogen  that  is  ionizable.  Like  the  lower 
members  of  this  large  series  it  is  a  volatile  liquid,  miscible  with 
water,  and  having  a  strong  acid  reaction.  In  the  succeeding 
members  the  non-ionizable  hydrogen  is  replaced  by  an  alkyl 
radical,  such  as  methyl  (CH3)  or  ethyl  (C2H5),  the  molecular 
weight  increasing  by  CH2,  the  boiling-point  rising  and  the  spe- 
cific gravity  falling  as  they  ascend.  The  higher  compounds  are 
light,  solid,  waxy  substances  without  pungent  odor,  insoluble  in 
water  and  having  very  little  acid  property. 

The  hydrogen  of  carboxyl  only  is  replaceable  by  metals  or 
basic  radicals,  forming  salts.  If  replaced  by  an  alcoholic  radical, 
the  product  is  called  a  compound  ether.  The  basicity  of  an  organic 
acid  is  in  accordance  with  the  number  of  carboxyl  groups  it  con- 
tains. The  fatty  acids  are  monobasic,  but  some  other  organic 
acids  are  dibasic  and  some  are  tribasic,  forming  normal  acid, 
and  basic  salts.  Sometimes  the  basicity  is  indicated  by  a  formula 
which  sets  apart  the  hydroxyl,  all  the  remainder  being  called  the 
acid  radical;  thus,  C2H3O  is  called  acetyl  when  acetic  acid  is 
written  C2H3O  .HO.  The  general  formula  for  the  fatty  acids  is 
CnH2n+1  CO  .  OH. 

Melts  at 

C.         F. 

8.3°  (47°) 

16.5°  (62°) 

-24°  (-11-2°) 

—4°  (24-8°) 
— 16°  (3-2°) 
—2°  (28.4°) 
62°  (143-6°) 
69°  (158°) 


Fatty  acids. 

Formic,      H .  COOH 
Acetic,        CH3 .  COOH 
Propionic,  C2H5 .  COOH 
Butyric,      C3H7 .  COOH 
C4H9.COOH 
C5Hn  .  COOH 


Occurs  in 


Valeric, 
Caproic, 


Palmitic,    C15H3i.COOH 
Stearic,       C17H35 .  COOH 


Nettles  and  ants. 

Organic  decompositions,  vinegar. 

Urine,  sweat. 

As  glycerid  in  butter. 

Valerian  plant. 

As  glycerid  in  butter. 

As  glycerid  in  palm  oil,  solid  fats. 

As  glycerid  in  stearin,  lard,  tallow. 


27 


418  ALIPHATIC    COMPOUNDS 

Nine  acids  of  no  medical  importance  come  between  caproic 
and  palmitic.  The  higher  members  end  in  melissic  acid, 
C29H59COOH,  found  in  beeswax. 

Formic  Acid. — This  was  first  observed  in  the  stinging  liquid 
ejected  by  the  ant  (jormica).  It  is  also  found  in  the  stings  of  the 
nettle.  When  carbon  monoxid  is  passed  over  gently  heated 
potassium  hydroxid,  potassium  formate  is  obtained: 

CO         +          KOH  H.COOK. 

The  acid  is  set  free  by  distilling  the  formate  with  sulphuric 
acid.  The  usual  method  of  preparing  it  is  by  heating  oxalic  acid 
with  glycerin.  The  formic  acid  at  once  combines  with  the  glyc- 
erin, which  readily  gives  it  up  on  distillation.  Oxalic  acid  has 
two  carboxyl  groups  and  breaks  up  as  shown  in  the  formula: 

1COOH        =        H.COOH        +         CO,. 

i  I 

COOiH 

Proof  that  formic  acid  is  closely  related  to  carbonic  acid  is 
found  by  the  action  of  carbonic-acid  water  on  potassium: 

2H2C03     +      2K     =      K.C02H     +      KHC03     +      H2O. 

Potassium  formate.       Potassium  carbonate. 

Properties. — Formic  acid  is  a  colorless,  volatile  liquid  with  a 
peculiar  pungent  odor,  marked  acid  properties,  and  highly  irritat- 
ing local  effects. 

Tests. — Its  powerful  deoxidizing  action  enables  it  to  precipitate 
metallic  silver  from  warm  ammoniacal  solutions  of  the  oxid  (see 
Tollen's  reagent,  p.  410).  This  reducing  power  is  due  to  the 

O^ 
aldehyd  group   shown  in  its   structure       /C— OH.      The  other 

fatty  acids  are  not  reducing  agents  because  they  do  not  have  the 
aldehyd  group  seen  in  the  formic-acid  formula.  Heated  with 
concentrated  sulphuric  acid,  H2O  is  abstracted,  freeing  CO.  This 
proves  that  carbon  monoxid  is  an  anhydrid  of  formic  acid: 

CH2O2       =        H2O       +        CO. 

Acetic  acid,  CH3.COOH,  is  so  readily  formed  by  natural 
fermentations  that  its  general  properties  have  been  known  from 
the  earliest  times.  Other  substances  discovered  later  to  have 
a  similar  sharpness  in  taste  were  given  the  name  acids,  derived 
from  the  same  root  word.  Its  synthesis  starts  with  the  action  of 
iodin  on  methane,  making  methyl  iodid  CH3I.  In  the  presence 
of  potassium  cyanid  this  changes  to  methyl  cyanid.  Thus: 

CH3I     +     KCN     =     CH3 .  CN     +     KI. 


FATTY    ACIDS  419 

Boiling  methyl  cyanid  with  a  dilute  mineral  acid  causes  it  to 
react  with  water  and  yield  acetic  acid  and  ammonia: 


2 

Methyl  cyanid.  Water.  Acetic  acid. 

The  above  series  of  reactions  constitutes  strong  proof  that  the 
structural  formula  of  acetic  acid  must  include  methyl,  CH3,  and 
hydroxyl  associated  with  carbonyl  in  the  formula— 


Vinegar  Method.  —  Acetic  acid  is  produced  on  a  large  scale  in 
vinegar  making.  Oxidation  of  ethyl  alcohol  results  from  the 
influence  of  a  microscopic  unicellular  plant,  Mycoderma  aceti, 
which  in  large  masses  is  called  mother  of  vinegar.  To  facilitate 
the  process  of  conveying  oxygen  from  the  air  the  natural  alcoholic 
liquor,  weak  wine,  cider,  or  beer  is  made  to  trickle  slowly  through 
a  ventilated  cask  over  shavings  already  wet  with  old  vinegar. 

Pyroligneous  Method.  —  Among  the  products  of  dry  distilla- 
tion of  wrood  are  methyl  alcohol  (wood  spirits)  and  acetic  acid. 
The  acid  is  fixed  with  lime,  forming  calcium  acetate,  the  other 
volatile  products  being  distilled  off.  Distilled  with  sulphuric  acid, 
the  acetic  acid  separates  in  the  distillate.  By  repeated  distillations 
and  freezing  this  is  purified  and  freed  from  water  to  make  anhy- 
drous acetic  acid. 

A  little  water  remains  (not  more  than  i  per  cent.)  in  the  com- 
mercial acid  known  as  glacial  acid  or  acidum  aceticum  glaciate. 
This  is  a  colorless  crystalline  solid  with  an  irritating  odor,  melting 
at  15°  C.  (59°  F.)  to  form  a  strongly  acid  liquid  soluble  in  water, 
alcohol,  and  ether. 

Acidum  aceticum,  U.  S.  P.,  contains  only  36  per  cent,  of  the 
anhydrous  acid,  and  acidum  aceticum  dilutum,  U.  S.  P.,  has  6  per 
cent. 

Vinegar.  —  In  the  household  a  mixture  containing  from  3  to  6 
per  cent,  of  acetic  acid  is  commonly  used.  The  flavor  and  the 
color  of  the  vinegar  varies  somewhat  according  to  its  source  — 
wine,  cider,  beer,  or  an  artificial  mixture  of  essences  and  coloring 
matter  with  dilute  acetic  acid.  Should  mineral  acids  be  used  as 
adulterants,  they  can  be  detected  by  the  tests  mentioned  in  other 
places. 

Tests  for  Acetic  Acid.  —  It  has  a  characteristic  odor.  When 
heated  with  alcohol  and  sulphuric  acid  it  develops  the  agreeable 
odor  of  acetic  ether.  With  ferric  chlorid  it  yields  a  deep  red  color 


420  ALIPHATIC    COMPOUNDS 

which,  when  boiled,  changes  to  a  red-brown  precipitate  of  ferric 
subacetate. 

Chloracetic  Acids. — One,  two,  or  all  three  hydogen  atoms 
in  the  methyl  group  of  acetic  acid  may  be  substituted  by  chlorin, 
making  the  three  acids  monochloracetic,  CH2C1COOH;  dichlor- 
acetic,  CHC12COOH,  a  colorless  liquid  used  in  medicine;  and  tri- 
chloracetic,  U.  S.  P.,  CC13COOH,  a  crystalline  substance  used  as  a 
reagent  for  albumin.  It  is  deliquescent,  has  a  pungent  odor,  and  is 
soluble  in  water,  alcohol,  and  ether.  It  is  a  local  caustic  used 
to  destroy  warts  and  other  cutaneous  growths. 

Butyric  Acid. — Two  isomeric  forms  are  known  of  the  for- 
mula C3H7COOH.  Normal  butyric  acid  occurs  in  animals  and 
vegetables,  sometimes  free,  but  more  often  as  an  ester  with  glyc- 
erin. This  ester,  butyrin,  is  characteristic  of  butter,  from  which 
butyric  acid  is  set  free  by  the  rancid  fermentation.  This  acid 
gives  the  rancid  odor  and  flavor.  When  milk  sours,  lactose  is  con- 
verted into  lactic  acid  by  the  lactic  ferment  from  various  bacteria. 

C12H220U         +         H20  4C3H603 

Lactose.  Lactic  acid. 

By  adding  decaying  cheese  the  lactic  acid  is  broken  up  by  the 
butyric  ferment  secreted  by  some  putrefactive  bacteria: 

2C3H603     -     C4H802     +     2C02     +     2H2. 

Lactic  acid.  Butyric  acid. 

Butyric  acid  is  a  thick,  sour,  colorless  liquid,  smelling  like  stale 
perspiration  or  rancid  butter.  It  mixes  with  water  in  all  pro- 
portions and  boils  at  163°  C.  (325.4°  F.). 

Valeric  Acid  (C4H9 .  COOH).— Of  the  four  isomeric  forms 
known,  two  of  them  occur  in  the  plants  valerian  and  angelica 
root,  and  the  mixture  obtained  by  distillation  of  valerian  is  the 
valeric  acid  used  in  medicine.  This  is  an  oily  liquid  boiling  at 
174°  C.  (345.2°  F.)  and  forming  valuable  medicinal  salts — the 
valerates  of  zinc,  ammonium,  iron,  and  quinin. 

Palmitic  acid,  C15H31COOH,  and  stearic  acid,  C17H35 .  COOH, 
occur  abundantly  in  animal  and  vegetable  fats  as  glycerin  esters 
— palmitin  and  stearin.  In  stearin  candle-making  these  are  pre- 
pared on  a  large  scale.  They  are  waxy,  colorless  solids,  melting 
respectively  at  62°  C.  (143.6°  F.)  and  69°  C.  (156.2°  F.).  They 
are  soluble  in  alcohol  and  ether,  but  insoluble  in  water. 

Margaric  acid,  C16H33COOH,  does  not  occur  in  nature, 
though  the  name  was  formerly  given  to  a  mixture  of  palmitic  and 
stearic  acids.  It  is  now  reserved  for  an  acid  which  is  prepared 
artificially. 


ORGANIC    ACIDS,   NOT    FATTY  421 


ORGANIC  ACIDS,  NOT  FATTY 

Oleicacid,  U.  S.  P.,  C17H33 .  COOH,  belongs  to  the  acrylic  acids, 
which  differ  from  the  fatty  acids  as  the  olefins  from  the  paraffins. 
It  is  usually  found  in  plants  and  animals,  associated  with  palmitic 
and  stearic  acids  as  glycerin  esters. 

In  the  process  of  soap-making  this  acid  is  produced  from  fats. 
The  other  acids  crystallize,  leaving  oleic  acid  as  an  oily  liquid  at 
temperatures  above  14°  C.  (57.2°  F.). 

Oxalic  Acid,  U.  S.  P.,  (H2C2O4).— Glycol,  C2H4 .  (OH)2,  has 
been  described  (p.  401)  as  a  dihydric  alcohol  containing  two 
hydroxyl  groups.  As  a  primary  alcohol  it  yields  on  oxidation  an 
acid  with  one  carboxyl  group— glycollic,  CH2(OH)COOH, 
and  a  remaining  alcohol  group,  CH2OH,  thus  forming  a  hydroxy- 
or  alcohol-acid.  Another  acid  is  formed  when  it  is  more  com- 
pletely oxidized  with  two  carboxyl  groups,  oxalic  acid,  2(COOH): 

CH2OH  COOH 

|  +         2O2         =  |  +         2H2O. 

CH2OH  COOH 

Glycol.  Oxalic  acid. 

It  is  dibasic,  making  two  series  of  salts,  neutral  and  acid  oxalates, 
which  are  fully  discussed  in  another  place  (p.  200). 

Succinic  Acid,  H2C4H4O4. — There  are  two  isomers  of  this  acid 
namely: 

CH2COOH  CH(COOH)2. 

Ordinary  succinic    |  ;  isosuccinic   | 

CH2COOH  CH3 

They  are  distinguished  by  heating  to  150°  C.  (302°  F.);  the  ordi- 
nary acid  is  not  changed,  but  the  isosuccinic  splits  to  form  pro- 
pionic  acid  and  carbon  dioxid.  A  trace  of  the  ordinary  acid  is 
produced  in  alcoholic  fermentation  and  is  also  found  in  the  gastric 
contents  when  mould  is  present. 

Detection. — The  gastric  contents  are  shaken  with  ether,  which 
is  then  separated  by  a  funnel  and  evaporated  to  dryness.  The 
residue  is  dissolved  in  weak  ammonia,  the  excess  of  ammonia 
then  boiled  off,  and  the  neutral  solution  remaining  is  added  to 
dilute  ferric  chlorid;  a  brown-red  precipitate  is  formed  by  succinic 
acid. 

Glutaric  Acid,  COOH(CH2)3COOH.—  Normal  pyrotartaric, 
the  next  member  of  the  homologous  series  with  succinic  acid, 
crystallizes  in  large  plates,  soluble  in  water.  It  forms  an  amino- 
acid  (glutamic)  which  is  a  constituent  of  proteid  matter. 


422  ALIPHATIC    COMPOUNDS 

HYDROXY-  OR  ALCOHOL-ACIDS 

Lactic  Acid,  U.  S.  P.,  (C3H6O3)  (Hydroxypropionic  Acid).—  It 
has  been  stated  above  that  this  acid  is  the  characteristic  product 
of  the  lactic  fermentation  occurring  in  sugar,  starch,  and  other 
carbohydrates,  when  animal  nitrogenous  matter  is  present  (see 
Butyric  Acid,  p.  420).  It  can  be  prepared  also  by  oxidizing  pro- 
pyleneglycol  with  nitric  acid.  Several  acids  are  known  of  the  same 

OTT 
molecular  formula,  and  three  are  stereo-isomeric,  C 


These  are  distinguished  apart  by  differences  of  crystalline  structure, 
solubility,  and  effects  on  polarized  light.  This  last  property  gives 
the  names,  inactive,  dextro-,  and  levo-rotatory  lactic  acids. 

Ordinary  Lactic  Acid  (Inactive  to  Polarized  Light).  —  This  is  the 
acid  present  in  sour  milk  and  in  the  gastric  contents  in  the  first  half- 
hour  of  digestion  (see  pp.  544  and  552).  The  lactic  acids  are  thick, 
sour  liquids,  miscible  with  water  and  alcohol  in  all  proportions. 

From  organic  mixtures  lactic  acid  can  be  separated  by  first 
acidifying  with  sulphuric  acid  and  shaking  with  ether.  This 
ethereal  extract,  underlaid  with  solution  of  ferric  chlorid,  gives 
at  the  line  of  contact  a  yellow  band.  It  is  a  monobasic  acid, 
forming  metallic  salts  and  esters  known  as  lactates.  It  contains 
the  alcoholic  group,  >CH  .  OH  and  shows  many  of  the  reactions 
of  a  secondary  alcohol. 

Sarcolactic  acid  (C3H6O3)  (paralactic  acid,  dextrolactic  acid) 
occurs  in  the  juices  of  muscles,  and  can  be  prepared  from  extract 
of  meat.  The  constitution  and  chemical  behavior  are  the  same 
as  those  of  ordinary  lactic  acid,  but  optically  this  acid  is  active, 
turning  the  polarized  ray  to  the  right.  The  acid  rotating  to  the  left, 
levolactic,  is  produced  by  a  special  ferment  working  on  cane-sugar. 

Oxyblltyric  Acid.  —  In  the  oxidation  of  secondary  normal 
butyl  alcohol,  (p.  400),  the  first  group*  only  (CH3)  is  oxidized  to 
CO  OH.  This  must  always  be  at  either  end  of  the  chain  to 

/OTT 
give  the  carbon  atom  the  three  valences  needed  for  the  —  C^o    . 

The  alcohol  hydroxyl  may  be  attached  to  any  of  the  remaining  C 
atoms,  and  thus  make  it  a  hydroxyacid  or  oxyacid.  The  rela- 
tive position  of  the  HO  group  in  the  three  possible  oxybutyric 
acids  are  indicated  below  by  the  Greek  letters  (a)  alpha,  (ft)  beta, 
fr)  gamma. 

COOH  COOH  COOH  COOH 

CH,  a  CHOH  a  CH,  a  CH, 

CH,  pCH,  0CHOH  /3CH2 

CHS  yCHs  7CHS  y  CH2OH 

Butyric  acid.  a  Oxybutyric  acid.          ft  Oxybutyric  acid.        y  Oxybutyric  acid. 


ORGANIC    ACIDS,   NOT    FATTY  423 

The  levo  beta  oxybutyric  acid  is  especially  interesting,  as  it  is 
found  associated  with  diacetic  acid  and  acetone  in  the  blood  and 
urine  of  severe  cases  of  diabetes.  It  is  a  factor  in  the  acidosis  of 
diabetic  coma. 

Test. — Detection  in  the  urine  is  not  easy.  Dependence  is 
placed  usually  on  the  red  ferric  chlorid  reaction  given  by  its  con- 
stant companion,  diacetic  acid.  One  method  is  to  remove  dex- 
trose from  the  urine  by  fermentation  and  then  estimate  the  re- 
maining oxybutyric  acid  by  its  levorotation  of  the  ray  in  the 
polariscope  (p.  61). 

Tartaric  acid,  U.  S.  P.,  C4H6O6,  is  a  constituent  of  a  large 
number  of  plants,  occurring  in  many  fruits,  such  as  the  berries  of 
the  mountain  ash,  and  particularly  in  grapes.  In  the  making  of 
wine  the  secondary  fermentation  in  the  cask  causes  the  formation 
of  a  dark  red  deposit.  This  deposit,  argol,  or  crude  tartar,  is 
an  impure  potassium  bitartrate.  By  solution  and  recrystalliza- 
tion  this  is  purified  and  then  treated  with  chalk  and  calcium 
chlorid  to  form  a  precipitate  of  calcium  tartrate.  With  dilute 
sulphuric  acid  the  calcium  is  removed  as  insoluble  sulphate  and 
tartaric  acid  is  left  in  solution.  The  solution  is  filtered  off  and 
crystallized  in  large  colorless  prisms  without  odor,  but  with  a 
sour  taste.  This  is  the  ordinary  tartaric  acid  (dihydroxy-succinic 
acid),  which  is  dibasic,  forming  neutral  and  acid  tartrates,  such 
as  monopotassium  tartrate,  sodium  potassium  tartrate,  and  anti- 
mony potassium  tartrate. 

By  synthesis  it  can  be  built  up  in  such  a  way  as  to  indicate 
that  its  constitution  consists  of  two  similar  groups  united,  as  a 
dihydroxy-dicarboxylic  acid: 

CH(OH)COOH 
CH(OH)COOH 

The  two  dark  carbon  atoms  are  linked  together  at  one  point, 
but  have  different  atoms  or  groups  at  other  points. 

When  substances  of  the  composition  C4H6O6  having  similar 
chemical  properties  are  studied  by  polarized  light,  four  different 
isomeric  modifications  are  recognized:  dextrotartaric,  levotartaric, 
mesotartaric,  and  racemic  acids.  These  examples  of  optic  activity 
are  regarded  as  proofs  of  the  rule  that  it  depends  upon  molecular 
asymmetry. 

Stereo-isomerism  is  isomerism  explained  by  differences  of 
arrangement  in  space  of  three  dimensions.  Ordinary  tartaric  acid 
crystallized  from  grape  juice  rotates  the  polarized  ray  to  the 
right,  but  the  remaining  juice  contains  another  acid,  racemic,  with 
the  same  formula,  C4H6O6,  and  identical  chemically,  but  different 


424 


ALIPHATIC    COMPOUNDS 


physically,  its  solution  being  inactive  to  polarized  light.  The 
sodium-ammonium  salts  of  these  acids  have  the  same  composi- 
tion, Na(NH4)C4H4O6,  and  the  same  difference  optically  as  their 
acids.  The  crystalline  form  of  the  tartrate  is  shown  in  D  (Fig. 
78)  while  the  racemate  is  found  to  crystallize  in  two  forms,  one 
like  D,  the  other  like  L,  each  the  reflected  image  of  the  other. 


V  L 

FIG.  78.— Isomeric  salts  of  tartaric  acid:  P=dextrorotatory;  Z,=levorotatory. 

The  differences  are  in  the  arrangement  of  the  small  faces  (a,  b), 
darkened  in  the  figure.  When  the  crystals  of  each  kind  are  set 
apart,  separately  dissolved,  and  tested  with  the  polariscope,  the 
solution  of  D  is  found  to  be  dextrorotatory,  and  that  of  L,  levo- 
rotatory.  There  is  then  a  dextrotartaric  acid  and  a  levotartaric 
acid.  If  these  solutions  of  equal  concentration  be  mixed,  they 


.D-tartaric  acid.  L-tartaric  acid.  Mesotartaric  acid. 

FIG.  79. — Isomeric  forms  shown  by  tetrahedral  models. 

neutralize  each  other  optically  and  racemic  acid  (D  +  L  tartaric 
acid)  is  produced. 

From  dibromsuccinic  acid  a  fourth  isomer,  ^,  mesotartaric  acid, 
is  obtained.  This  is  optically  inactive,  like  racemic  acid,  but  can 
not  be  split  into  the  right-  and  left-handed  acids. 

A  study  of  the  optically  active  substances  shows  that  this 
property  depends  upon  the  presence  in  the  molecule  of  an  asym- 


ORGANIC    ACIDS,   NOT    FATTY  425 

metric  carbon  atom — that  is,  one  which  is  joined  immediately  to 
four  different  atoms  or  groups.  Each  of  the  four  atoms  or  groups 
is  supposed  to  be  placed  on  one  of  four  different  lines  drawn  from 
the  center  of  an  imaginary  tetrahedron  to  the  four  corners. 

If  two  tetrahedral  models,  representing  two  compounds,  are 
manipulated  it  is  found  that  the  two  asymmetric  carbon  atoms 
are  capable  of  three  distinct  arrangements,  corresponding  to  the 
three  tartaric  acids,  the  fourth  being  an  externally  compensated 
mixture  of  two  others  (Fig.  79). 

Three  of  the  forms  may  be  represented  by  the  three  different 
graphic  formulas  below,  in  which  the  solid  black  letter  Q  stands 
for  an  asymmetric  carbon  atom. 

COOH  COOH  COOH 

H— C— OH      OH— C— H         H— C— OH 
OH— Q— H         H— C— OH       H— C— OH 

T  T  i 

COOH  COOH  COOH 

.D-tartaric  acid.  L-tartaric  acid.  Mesotartaric  acid. 

Using  tetrahedral  models  for  the  black-letter  carbon  atoms, 
these  compounds  are  represented  in  the  diagrams  above  (Fig. 
79),  where  the  groups  are  arranged  in  space  of  three  dimensions, 
thus  giving  a  perect  illustration  of  stereo-is omerism. 

Citric  acid,  U.  S.  P.,  C6H8O7,  is  found  free  in  the  juice  of  the 
lemon,  orange,  gooseberry,  raspberry,  and  many  other  sour  fruits. 
It  is  prepared  by  boiling  lemon  juice  and  neutralizing  with  calcium 
carbonate.  The  calcium  is  fixed  by  sulphuric  acid,  leaving  free 
citric  acid  in  solution.  The  filtrate  on  evaporation  deposits  large 
colorless  prismatic  crystals,  freely  soluble  in  water. 

It  is  extensively  used  in  pharmacy  to  prevent  the  precipitation 
of  ferric  hydroxid  and  other  hydroxids  from  their  salts.  The 
solutions,  thickened  by  evaporation  and  dried  on  glass  plates, 
yield  the  brilliant  scales  which  have  given  the  name  scale  prep- 
arations to  these  compound  tartrates  and  citrates. 

The  synthetic  reactions  of  this  acid  show  that  it  is  a  hydroxy- 
tricarboxylic  acid  of  the  constitution: 

CH2-  COOH 

C(OH)'COOH 

I 
CH2-  COOH. 

Being  tribasic,  it  forms  three  classes  of  salts,  in  which  one,  two, 
or  three  hydrogen  atoms  of  the  carboxyl  groups  are  replaced  by 
metals. 


426  ALIPHATIC    COMPOUNDS 

Tests  for  Tartaric  and  Citric  Acids.— Calcium  chlorid  yields 
a  white  precipitate  with  both.  Boiling  does  not  change  citrates, 
but  darkens  tartrates.  Potassium  permanganate  decolorizes  tar- 
trates,  but  turns  citrates  green. 

KETONE-ACIDS 

These  acids  contain  the  CO  of  ketones  as  well  as  the  CO  OH  of 
acids.  The  only  one  of  medical  interest  is  aceto-acetic  acid,  or 
diacetic  acid,  CH3CO  .  CH2COOH,  which  is  associated  with 
acetone  in  the  urine  and  blood  of  severe  cases  of  diabetes.  It 
is  a  colorless  syrupy  liquid.  It  is  believed  to  be  derived  in  the 
blood  from  /5-oxbutyric  acid  CH3 .  CHOH  .  CH3 .  COOH  by  oxi- 
dation. It  is  called  diacetic  acid  because  two  molecules  of  acetic 
acid  are  united  in  it  by  the  elimination  of  H2O,  thus: 

CH3 .  CO:OH-H;CH2 .  COOH. 

Later  oxidation  readily  removes  the  COOH  group,  leaving  acet- 
one CH3 .  CO  .  CH3  (p.  413). 

Test. — Having  acidulated  50  c.c.  of  urine  with  sulphuric  acid, 
it  is  shaken  with  an  equal  volume  of  ether.  The  ether  separated 
is  shaken  with  a  small  quantity  of  dilute  solution  of  ferric  chlorid. 
A  red  or  violet  color  in  the  reagent  indicates  aceto-acetic  acid. 

Fallacy. — Antipyrin,  salicylates,  and  other  synthetic  aromatic 
drugs  give  a  blue-red  or  purple  color  to  ferric  chlorid,  but  the 
color  is  deepened  by  warming,  whereas  the  diacetic-acid  red  ether 
disappears  or  is  greatly  lessened  (Plate  8,  Fig.  6). 


FATS  AND  FATTY  OILS 

Tallow  is  the  solid  fat  obtained  from  beef  and  mutton  suet  by 
expression  when  kneaded  in  a  muslin  bag  under  hot  water.  Lard 
is  hog  fat  treated  by  a  similar  process.  Fatty  oils  are  obtained 
by  pressing  the  seeds  or  fruits  of  cotton,  olive,  linseed,  and  palm. 
When  treated  with  superheated  steam  all  of  them  absorb  water  and 
break  up  into  glycerin  (glycerol)  and  the  acids,  oleic,  palmitic, 
and  stearic.  Distilled  in  the  hot  steam,  these  pass  over  and  are 
collected  in  the  receiver  with  the  acids  in  a  semisolid  mass,  floating 
on  the  dilute  glycerin. 

Fat  +  water  at  200°  C.   =  glycerin  +  acid. 

To  express  the  movement  of  the  atoms  the  following  equation 
is  used,  the  fat  being  tristearin: 


FATS    AND    FATTY    OILS  427 

CH,.O.OC.C1TH,5  CHa.OH         HO.OC.^H^ 

CH  .O.OC.C17H35  +  3H20   =  CH.OH   +   HO.OC.C,^ 
CH2.O.OC.C17H85  CH2.OH         HO.OC.C^. 

Tristearin  Glycerin  Stearic  acid 

(i  molecule)  (i  molecule).  (3  molecules). 

Glycerin  has  already  been  described  as  a  tri-acid  base,  under 
the  class  of  Trihydric  Alcohols  (p.  401);  its  formula  is  C3H5(OH)3, 
or  glyceryl  trihydroxid.  The  fats  are  sometimes  called  glycerids, 
glycerin  esters,  or  ethereal  salts.  They  are  named  after  the  acids 
forming  them,  as  tripalmitin  (or  glyceryl  tripalmitate),  tristearin, 
and  triolein.  The  firm  solid  fats,  such  as  tallow,  get  their  hafdness 
at  ordinary  temperatures  from  their  large  proportion  of  tristearin 
and  tripalmitin.  Those  that  are  soft,  like  lard,  have  a  large  pro- 
portion of  olein,  and  the  liquid  oils  are  composed  chiefly  of  that 
constituent. 

Saponification. — The  fats  decompose  more  readily  by  the 
action  of  alkalis  than  by  hot  water  alone.  The  acids  leave  the 
weak  base  glycerin  to  join  the  alkali  metals,  forming  soaps.  A 
soap  then  is  a  salt  containing  an  alkali  metal  united  with  oleic, 
palmitic,  or  stearic  acids.  They  remain  dissolved  in  water  until 
common  salt  is  added  to  make  them  insoluble,  when  the  curds  of 
soap  rise  to  the  surface.  The  glycerin  is  left  dissolved  in  the  liquid 
with  the  mineral  salt. 

/O.C18H350  X)H 

CSH5^O.C18H350  -f  3KOH  ^  C3H6^OH 

XO.C18H35O  \OH 

Glyceryl  stearate  (stearin).  Glycerin.  Potassium  stearate 

(soft  soap) . 

When  sodium  replaces  the  hydrogen  of  stearic,  palmitic,  and 
oleic  acids  the  product  is  hard  soap  (sapo,  U.  S.  P.).  If  potassium 
be  the  alkaline  metal,  then  soft  soap  (sapo  mollis,  U.  S.  P.)  is  the 
product. 

From  this  first  process  of  splitting  up  a  fatty  ester  of  glycerin 
with  a  metallic  hydroxid  the  term  saponification  was  extended 
to  the  decomposition  of  esters  by  alkalis,  even  when  the  product  was 
not  a  soap.  Thus: 

(C2H5)2SO4   +   2KOH   =    2C2H5OH   +    K2SO4. 

Ethyl  sulphate.  Alcohol. 

Experiment  i. — Make  a  solution  of  potassium  hydroxid,  10  gm., 
in  100  c.c.  of  water  and  put  in  a  beaker  with  25  gm.  of  tallow. 
Boil  and  stir  about  half  an  hour  until  oil  globules  disappear  from 
the  surface.  The  homogeneous  liquid  is  a  mixture  of  glycerin, 
soap,  and  potassium  hydroxid.  Add  a  solution  of  15  gm.  of 
sodium  chlorid  in  75  c.c.  of  water  and  boil  again.  The  soft 
potash  soap  changes  to  hard  sodium  soap,  which  separates  and 
floats  on  the  briny  liquid. 


428  ALIPHATIC    COMPOUNDS 

Experiment  2. — Skin  off  the  sodium  soap  or  use  a  piece  of  ordi- 
nary soap;  dissolve  in  water,  with  the  aid  of  alcohol.  Add  solution 
of  cilcium  chlorid;  a  white  precipitate  of  insoluble  lime  soap 
separates. 

Hydrolysis  is  a  term  for  the  analogous  decomposition  when 
water  is  absorbed  and  not  the  alkaline  hydroxid.  It  implies  that 
the  breaking  up  of  one  compound  into  two  or  more  is  consummated 
by  the  participation  in  the  process  of  the  elements  of  water  as  in  the 
splitting  of  fats  by  superheated  steam  (p.  402).  Thus: 

C2H5 .  C2H302  +  H20  =  C2H402  +  C2H5OH 

Ethyl  acetate.  Acetic  acid.  Alcohol. 

Hydrolysis  may  be  brought  about  by  an  enzym  of  the  pan- 
creatic juice  known  as  steapsin.  The  process  is  sometimes 
referred  to  as  hydrolytic  cleavage. 

Experiment  3. — Put  in  a  test-tube  5  c.c.  of  oil  and  a  few  drops 
of  oleic  acid,  add  10  drops  of  a  strong  solution  of  sodium  carbonate 
and  shake  well.  The  sodium  and  the  free  acid  unite  to  make 
a  soap  which  envelops  the  fat  globules  so  that  they  do  not  coalesce, 
but  make  a  permanent  emulsion. 

Butter. — The  butter-jat  of  milk  is  a  complex  mixture  of  glycerids, 
characterized  by  a  relatively  larger  amount  of  lower  volatile  fatty 
acids.  When  decomposed  by  hydrolysis  it  yields  about  95  per 
cent,  of  fatty  acids,  85  to  90  per  cent,  of  which  are  the  non-volatile, 
insoluble,  higher  acids — stearic,  palmitic,  oleic,  myristic — and  the 
remainder,  5  to  10,  is  made  up  of  the  volatile,  soluble  acids — 
butyric,  caproic,  caprylic,  and  capric.  No  other  fat  yields  so  large 
a  percentage  of  volatile  acids  when  distilled  with  water. 

Oleomargarin  is  an  imitation  of  butter  in  color,  odor,  and 
taste.  It  is  manufactured  from  beef  suet.  The  beef  fat  is  minced 
fine,  heated  by  steam,  and  at  a  certain  temperature  put  under 
pressure.  A  yellow  oil  (oleo  oil}  exudes  and  solid  stearin  remains. 
The  oleo  oil  is  churned  with  milk  to  get  the  butter  flavor  and 
colored  with  artificial  butter  yellow.  When  the  process  is  care- 
fully conducted  a  product  is  obtained  which  may  not  be  so  easily 
digested  as  butter,  but  which  is  wholesome  and  nutritious.  But- 
terin  and  suin  are  of  similar  manufacture,  using  the  fat  not  only 
of  beef,  but  also  of  mutton;  and  sometimes  they  contain  lard  and 
cotton-seed  oil. 

Properties  of  Fats. — When  pure,  the  fats  are  without  odor 
or  color,  leave  a  greasy  stain  on  paper,  are  lighter  than  water, 
with  which  they  do  not  mix.  They  are  soluble  in  ether,  chloroform, 
carbon  disulphid,  benzol,  alcohol,  etc.  When  the  solid  fats  are 
dissolved  in  ether  or  chloroform  and  evaporated  on  the  slide  of  a 
microscope,  characteristic  crystals  are  seen.  As  found  in  nature, 


FATS    AND    FATTY    OILS  429 

they  have  taste,  odor,  and  color,  due  to  more  or  less  impurity. 
On  standing  they  become  rancid — that  is,  they  acquire  an  un- 
pleasant smell  and  taste  and  an  acid  reaction.  This  is  due  to  the 
action  of  oxidizing  ferments,  which  in  the  case  of  butter  may  be 
prevented  or  retarded  by  the  admixture  of  antiferments,  such  as 
boric  acid.  Rancidity  is  sometimes  corrected  and  the  butter 
''renovated"  by  heating  with  solution  of  sodium  carbonate. 

Fats  and  fatty  acids  are  extracted  from  other  material  by 
shaking  with  ether,  which  dissolves  them,  but  not  the  mineral  salts, 
proteins,  or  carbohydrates.  A  separating  funnel  lets  the  aqueous 
material  run  off  first,  retaining  the  ether. 

Tests. — i.  Fats  are  the  only  substances  that  are  stained  by  the 
alcoholic  solution  of  red  Sudan  III. 

2.  Osmic  acid,  in  i  per  cent,  aqueous  solution,  stains  olein 
black,  but  does  not  stain  the  other  fats.  Olein  is  always  present 
in  animal  fats. 

Fats  in  the  Body. — A  certain  percentage  of  fats  is  present 
in  almost  all  our  food-stuffs.  They  make  up  nearly  all  of  the 
weight  of  olive  oil,  cream,  butter,  bacon,  and  the  fatty  tissue  of 
ordinary  meats.  The  fundus  of  the  stomach  secretes  a  lipase 
which  can  split  emulsified  fat  of  milk.  Fats  are  not  completely 
digested  until  they  reach  the  small  intestine,  where  they  undergo 
hydrolytic  cleavage  (p.  428)  by  the  action  of  a  pancreatic  enzym, 
steapsin,  and  another  lipase  of  the  bile  into  glycerin  and  the  fatty 
acids.  Some  of  the  free  acid  unites  with  the  sodium  of  the  alkaline 
bile  and  intestinal  juices  to  form  a  soap. 

This  soap  emulsifies  the  rest  of  the  fat,  hastening  the  action  of 
the  steapsin  upon  it,  and  promoting  its  absorption.  It  is  a  growing 
opinion  that  the  fat  is  all  split  first  and  passes  into  the  intestinal 
cells  in  solution  as  soap,  glycerin,  and  free  acid,  which  during 
transmission  are  recombined  into  molecular  fat  by  the  cells, 
reversing  the  reaction  and  splitting  off  the  sodium.  Some  of  the 
stored  fat  of  adipose  tissue  in  the  body  is  derived  from  sugar  and 
some  from  proteid  substances,  beside  what  may  be  obtained  from 
fatty  foods.  Most  of  the  fat  of  food  is  oxidized  to  CO2  and  H2O 
in  the  tissue  cells  as  fast  as  it  comes  to  them,  affording  molecular 
and  chemical  energy  and  maintaining  the  normal  temperature. 
Being  rich  in  carbon,  fat  is  very  combustible  and  liberates  a  large 
amount  of  heat.  The  stored  fat  is  a  reserve  of  potential  energy 
brought  into  use  in  wasting  diseases  attended  by  failure  of  nutrition. 

Waxes. — The  class  of  which  beeswax  is  a  member  does  not 
have  glycerin  as  a  component.  It  includes  the  esters  of  mona- 
tomic  alcohols,  such  as  melissyls  up  to  C30  united  with  higher  fatty 
acids  up  to  C18. 


430  ALIPHATIC    COMPOUNDS 


ESTERS 

COMPOUND  ETHERS,  ETHEREAL  SALTS 

In  the  presence  of  acids  the  alcohols  behave  like  metallic  hy- 
droxids  replacing  acid  hydrogen  with  a  radical,  with  water  as 
a  by-product.  These  are  sometimes  called  ethereal  salts,  but 
a  better  name  is  esters,  as  they  do  not  dissociate,  after  the 
manner  of  true  salts.  Mention  has  been  made  of  the  first  reaction 
between  sulphuric  acid  and  alcohol,  producing  ethyl  hydrogen 
sulphate,  C2H5HSO4,  and  water  (p.  404),  the  intermediate  products 
in  the  conversion  of  alcohol  into  ether.  This  compound,  also 
called  ethyl  sulphuric  acid  and  sulphovinic  acid,  has  an  acid 
reaction  and  acts  like  a  monobasic  acid,  since  it  retains  one  atom 

OP  TT 

of  replaceable  hydrogen.     The  formula,  SO2<Qjj2     5'  is  typic  of 

a  class  known  as  ethereal  sulphuric  acids,  in  which  the  radical  (R) 
is  linked  to  the  sulphur  by  an  oxygen  atom,  while  in  sulphonic  acids 
the  radical  is  directly  united  to  the  sulphur  atom.  This  difference 
of  constitution  is  indicated  as  follows: 


/OR  CK   /R 

" 


Ethereal  sulphuric  acid.  Sulphonic  acid. 

For  the  hydrogen  of  the  —  OH,  metals  and  bases  can  be  sub- 
stituted, thus  constituting  a  large  class  known  as  ethereal  sulphatesy 

T-T 

' 


as  sodium  ethyl  sulphate,  SOj 

It  is  the  characteristic  of  sulphanion,  (SO4)",  to  form  with 
barium,  Ba**,  an  insoluble  BaSO4.  As  ethyl  sulphuric  acid  forms 
no  precipitate  with  barium  chlorid,  its  dissociation  must  be  into 
the  hydrogen  cation  and  a  complex  anion,  thus:  H'(C2H5SO4)'. 
In  order  to  precipitate  an  ethereal  sulphate  with  barium  chlorid 
this  complex  anion  is  first  broken  up  by  boiling  with  hydrochloric 
acid  to  liberate  (SO4)"  (p.  588). 

Ethyl  Nitrate  (C2H5.NO3)  (Nitric  Ether).—  Owing  to  the 
heat  evolved  and  explosive  violence  of  the  reaction,  it  is  not  pru- 
dent to  make  this  compound  by  the  direct  action  of  concentrated 
nitric  acid  upon  alcohol.  When  urea  is  present  to  decompose  the 
nitrous  acid  formed,  the  operation  is  much  less  violent  and  the 
distilled  product  is  ethyl  nitrate. 

It  is  a  colorless,  volatile  liquid,  with  an  agreeable  fruity  odor. 

Ethyl  nitrite  (C2H5  .  NO2)  (nitrous  ether)  can  be  prepared  by 
the  action  of  nitrous  acid  on  alcohol: 

C2H5OH     +      HN02     =      C2H5.N0 


ESTERS  43 1 

This  is  a  colorless,  volatile  liquid,  with  an  odor  like  that  of  apples. 
When  4  per  cent,  is  mixed  with  alcohol  it  is  employed  in  medicine 
as  sweet  spirits  oj  niter,  spiritus  cetheris  nitrosi. 

Amyl  nitrite  (C5Hn .  NO2)  (amylis  nitris),  prepared  by  the 
action  of  nitrous  fumes  on  amyl  alcohol.  It  is  a  yellowish  volatile 
liquid,  with  a  peculiar  fruity  and  suffocative  odor.  It  is  insoluble 
in  water.  The  8o-per  cent,  alcoholic  solution  is  used  in  medicine. 
Its  vapor  explodes  when  heated  to  95°  C.  (203°  F.). 

Toxicology. — When  inhaled  it  dilates  the  arteries,  causing 
flushing  of  the  face  and  a  sense  of  fulness  about  the  head.  It 
relieves  cardiac  tension  and  the  painful  feelings  of  angina  pectoris. 
In  poisonous  doses  it  produces  weakness,  nausea,  vomiting, 
thready  pulse,  stupor,  and  collapse  with  cyanosis. 

The  antidotes  are  strychnin  hypodermically,  and  digitalis. 
When  swallowed  it  may  be  detected  in  the  gastric  contents  by 
distillation,  carefully  protecting  the  distillate  from  evaporation. 
By  agitation  of  the  aqueous  distillate  with  ether  it  may  be  sep- 
arated. By  heating  with  potassium  hydroxid  the  amyl  nitrite 
forms  amyl  alcohol  and  potassium  nitrite.  The  latter  may  be 
identified  by  the  tests  for  nitrites. 

Nitroglycerin  (C3H5(NO3)3)  (glyceryl  trinitrate,  trinitrin, 
glonoiri)  is  an  ester  of  nitric  acid  and  glycerin.  It  is  prepared 
by  gradually  mixing  glycerin  with  sulphuric  and  nitric  acids. 
The  product  is  a  heavy  oil,  which  is  washed  thoroughly  with 
water  and  dried. 

Properties. — It  is  a  pale  yellow  oil  of  specific  gravity  of  1.6, 
with  a  sweet  taste,  insoluble  in  water,  soluble  in  ether,  and  spar- 
ingly soluble  in  alcohol.  It  ignites  with  difficulty  by  a  flame  in 
an  open  vessel,  but  when  suddenly  heated  to  250°  C.  (482°  F.) 
it  explodes.  Its  most  remarkable  property  is  that  of  exploding 
with  violent  energy  on  percussion.  The  complex  molecule  con- 
taining combustible  elements  in  intimate  association  with  oxygen 
instantly  breaks  up  into  a  large  volume  of  mixed  gases,  CO2,  H2O, 
and  free  N.  To  make  it  safer  when  handled  the  nitroglycerin 
is  absorbed  into  an  inert  infusorial  earth,  and  is  then  called 
dynamite.  This  does  not  explode  by  pressure  or  by  a  simple 
jar. 

When  mixed  with  guncotton  (nitrocellulose)  it  is  employed  as 
blasting  gelatin.  It  enters  into  the  composition  of  certain  forms 
of  smokeless  powders. 

Medical  Uses. — When  inhaled  nitroglycerin  causes  aching  and 
a  sense  of  fulness  with  throbbing  in  the  head.  Its  effects  on 
heart  diseases  are  like  those  of  amyl  nitrite,  only  intensified  and 
more  persistent.  By  relaxing  the  peripheral  vessels  it  relieves 
the  high  blood-pressure  and  spasmodic  pain  of  angina  pectoris. 


432  ALIPHATIC    COMPOUNDS 

Spiritus   glycerylis   nitratis   is    a    i-per    cent,    alcoholic    solution. 
Dose:   i  to  2  min. 

Toxicology  of  Nitroglycerin. — Powder  headache  is  a  symptom 
frequently  seen  in  persons  employed  in  the  manufacture  of  the 
high  explosives  containing  nitroglycerin.  One  drop  applied  to 
the  unbroken  skin  may  cause  prolonged  headache.  Criminals 
give  it  in  whisky  to  " knock  out"  the  victim. 

Symptoms. — Severe  headache  is  constantly  present,  with  gid- 
diness, fulness  of  the  arteries,  throbbing  of  the  temples,  and  mus- 
cular weakness.  Marked  distress  is  caused  by  vomiting,  diarrhea, 
and  griping  pains.  The  breathing  is  hurried  and  difficult;  cyanosis 
and  coma  soon  appear.  Habitual  exposure  and  dosing  soon  induce 
tolerance. 

Fatal  Dose. — A  few  drops  of  the  undilute  nitroglycerin  would 
probably  be  fatal.  Death  does  not  usually  occur  for  several 
hours,  even  after  large  doses. 

Treatment. — The  stomach  and  bowels  should  be  promptly 
washed  out  or  evacuated.  The  symptoms  should  be  treated  as 
they  arise. 

Postmortem  Appearances. — The  alimentary  tract  shows  con- 
gestion, due  to  local  irritation;  the  brain  and  meninges  are  hyper- 
emic. 

Detection. — Nitroglycerin  rapidly  decomposes  after  absorp- 
tion. It  must  be  sought  in  the  vomited  matters  and  contents  of 
the  stomach.  These  are  to  be  shaken  out  with  chloroform  or 
ether.  The  extract  evaporated  leaves  a  residuum  of  fat  and 
nitroglycerin.  Cold  alcohol  dissolves  the  nitroglycerin,  leaving 
the  fat,  and  evaporation  of  the  alcohol  gives  us  the  material  to 
test. 

Tests. — (i)  Heated  in  a  capillary  tube  nitroglycerin  explodes. 
(2)  Like  all  nitrates  and  nitrites  it  develops  a  crimson  color 
when  treated  with  brucin  and  a  drop  of  concentrated  sulphuric 
acid. 

ESTERS  OF  ORGANIC  ACIDS 

These  resemble  one  another  more  closely  than  do  the  esters  of 
the  diverse  mineral  acids.  They  are  formed  to  some  extent  when 
an  alcohol  is  treated  by  an  organic  acid,  such  as  formic,  acetic, 
or  butyric.  The  process  is  soon  arrested,  as  the  water  formed 
hydrolyzes  the  ethereal  salt,  reconverting  it  into  ester,  acid,  and 
alcohol,  an  equilibrium  resulting.  To  remove  the  water  the 
complete  process  requires  that  some  dehydrating  agent,  such  as 
sulphuric  or  hydrochloric  acid,  should  be  present. 

When  an  ester  such  as  ethyl  acetate  is  added  to  water  the 
process  is  reversed.  Alcohol  and  acetic  acid  are  formed  until 
all  four  are  present  in  a  certain  degree  of  concentration,  which  is 


CARBOHYDRATES  433 

maintained  until  a  dehydrating  agent,  such  as  sulphuric  acid,  is 
added.  This  breaks  up  the  phases  of  the  system  in  equilibrium 
by  removing  the  component  water.  The  double  arrows  of  the 
following  equation  mean  that  the  movements  are  opposite  in  direc- 
tion and  equal  in  velocity  (p.  83). 

Alcohol  +  Acetic  acid  ^^  Ethyl  acetate  +  Water. 

Ethyl  Acetate  (C2H5 .  C2H3O2)  (Acetic  Ether).— This  is  pre- 
pared by  mixing  alcohol,  acetic  acid,  and  strong  sulphuric  acid, 
and  distilling  by  heat.  The  distillate  is  shaken  with  a  strong 
solution  of  common  salt,  to  take  up  the  alcohol,  and  the  ethyl 
acetate  rises  to  the  top  as  a  colorless,  mobile,  oily-looking  fluid. 
It  has  a  pleasant  fruit-like  smell,  and  is  moderately  soluble  in  water. 
The  fine  bouquet  of  hock  wine  is  due  mainly  to  the  small  amount 
of  ethyl  acetate  it  contains. 

This  is  a  type  of  the  class  of  ethereal  salts  which  are  found 
naturally  in  fruits  and  flowers,  giving  to  them,  by  varied  blend- 
ings,  the  scent  and  flavor.  Artificial  fruit  essences  are  prepared 
after  processes  like  that  given  above  for  ethyl  acetate,  and  largely 
sold  to  flavor  ices,  syrups,  candies,  and  pastries.  Pear  oil  is  amyl 
acetate,  pineapple  oil  is  methyl  butyrate,  wintergreen  oil  is  methyl 
salicylate. 


CARBOHYDRATES 

THE  term  carbohydrate  is  applied  to  substances  composed  of 
carbon,  hydrogen,  and  oxygen,  the  two  latter  being  in  the  ratio 
to  form  water.  The  carbon  atoms  are  in  an  open  chain.  In  this 
group  will  be  found  the  most  important  solid  constituents  of 
plants  suitable  for  human  food — sugars,  starches,  gums,  and 
cellulose. 

For  good  reasons  substances  have  been  admitted  to  the  group 
which  are  known  to  contain  hydrogen  and  oxygen  in  a  ratio 
different  from  H2O. 

The  termination  -ose  is  used  to  denote  membership  in  the  car- 
bohydrates; thus,  dextrose,  levulose,  amylose. 

Properties. — Most  of  the  carbohydrates  are  fermentable  with 
yeast,  or  easily  change  to  fermentable  compounds.  They  are 
usually  neutral,  white,  non-volatile,  odorless  solids,  and  in  solution 
turn  a  polarized  ray  of  light  from  the  direct  path.  The  sugars  are 
sweet,  reduce  metallic  oxids,  and  change  by  oxidation  to  sac- 
charic, mucic,  or  oxalic  acids. 

Classification. — The    modern    division    of    carbohydrates    is 
into  simple  sugars,  compound  sugars,  and  starches,  or: 
28 


434 


ALIPHATIC    COMPOUNDS 


Monosaccharids  (monoses  or  simple  sugars),  which  cannot  be 
made  to  yield  other  sugars  by  the  action  of  dilute  acids  (glucose, 
levulose,  pentose,  galactose,  etc.).  About  12  simple  sugars  occur 
in  nature,  all  of  which,  and  in  addition  40  others,  purely  artificial, 
have  been  made  by  synthesis  in  the  laboratory. 

Disaccharids  (saccharobioses),  which,  by  boiling  with  dilute 
acids,  can  be  made  to  take  up  i  molecule  of  water  and  split  up 
into  2  simple  sugar  molecules  (saccharose,  maltose,  lactose,  etc.). 

Polysaccharids,  which  are  not  sugars,  but  by  the  hydrolytic 
action  of  boiling  dilute  acids  take  up  2  or  more  molecules  of  water 
and  yield  a  number  of  simple  sugar  molecules  (starches,  gums, 
cellulose,  etc.). 

MONOSACCHARIDS 

The  structure  of  the  monosaccharids  has  been  determined  as 
that  of  mixed  compounds,  which  are  either  alcohols  and  aldehyds 
(aldoses),  or  alcohols  and  ketones  (ketoses).  The  aldoses  contain 
the  alcohol  group,  CH2OH,  and  the  aldehyd  group,  COH;  the 
ketoses  have  the  same  alcohol  group  and  the  ketone  group  CO, 
linking  2  radicals. 

The  monosaccharids  are  called,  according  to  the  number  of 
carbon  atoms  they  contain,  trioses,  C3H6O3;  tetroses,  C4H8O4; 
pentoses,  C5H10O5;  hexoses,  etc.,  up  to  nonoses,  C9H18O9,  which 
have  9  carbon  atoms.  Only  those  containing  3  carbon  atoms  or 
a  multiple  of  three  (trioses,  hexoses,  nonoses)  are  capable  of 
alcoholic  fermentation  or  of  assimilation  by  digestive  processes. 
They  are  neutral,  white,  sweet,  odorless  compounds,  soluble  in 
water  and  sparingly  so  in  alcohol.  They  share  with  aldehyds  and 
kstones,  containing  a  number  of  alcoholic  groups,  a  reducing 
power  on  metallic  oxids;  hence  give  the  familiar  reaction  of  reduc- 
tion shown  by  Fehling's,  Boettger's,  and  Nylander's  tests  (p.  602). 
Minute  traces  of  any  sugar  are  detected  by  Molisch's  test  (p.  473), 
in  which  a  violet  color  is  developed  when  the  carbohydrate  is 
mixed  with  a  small  amount  of  alpha-naphthol  and  sulphuric  acid. 
This  is  due  to  a  combination  of  alpha-naphthol  with  the  fur- 
furaldehyd  formed  by  the  action  of  sulphuric  acid  on  the  sugar. 
Their  solutions  acidulated  with  acetic  acid  and  heated  with  phenyl- 
hydrazin  all  give  yellow  crystalline  precipitates,  called  osazones 
(Plate  3).  This  last  reaction  separates  the  sugars  from  aldehyds, 
ketones,  and  all  other  substances.  While  all  are  interesting  chemi- 
cally, to  the  physician  only  the  hexoses  and  pentoses  have  any 
importance. 

The  hexoses,  C6H12O6,  include  dextrose,  levulose,  and  galac- 
tose. Dextrose  (glucose)  is  called  also  grape  sugar,  because  it  is 
abundant  in  grapes  and  forms  the  brownish  warty  masses  on 


MONOSACCHARIDS  435 

raisins.  Mixed  with  levulose  (fructose)  it  is  widely  distributed  in 
the  sweet  juices  of  fruits  and  in  honey.  Human  blood  and  urine 
in  their  normal  condition  may  contain  traces,  but  not  more  than 
o.i  per  cent.,  revealed  by  very  delicate  tests.  In  diabetes  mellitus 
the  proportion  rises  sometimes  higher  than  5  per  cent.,  and  then 
constitutes  the  chief  phenomenon  of  disease. 

Preparation. — When  a  solution  of  starch  or  other  polysac- 
charid  is  acidulated  with  sulphuric  or  some  other  mineral  acid 
and  boiled,  the  starch  is  hydrolyzed  and  splits  up,  forming,  when 
dry,  the  commercial  grape-sugar,  of  which  60  per  cent,  is  true 
glucose.  Sometimes  the  product  is  not  evaporated  to  dryness, 
and  is  a  thick,  colorless  syrup,  commercial  glucose,  which  con- 
tains, besides  sugar,  some  dextrins  and  nitrogenous  bodies. 

From  both  of  these  products  the  sulphuric  acid  is  removed  in 
the  manufacture  by  neutralizing  with  calcium  carbonate,  which 
precipitates  calcium  sulphate.  As  commercial  sulphuric  acid 
often  contains  traces  of  arsenic  and  lead,  it  is  not  surprising  that 
glucose  made  by  its  aid  sometimes  causes  slow  poisoning.  Wide- 
spread epidemics  have  resulted  from  brewing  beer  with  such 
a  glucose  (p.  288). 

Sulphurous  acid  is  sometimes  used  to  decolorize  the  syrup,  and 
sulphites  may  be  left  in  it  as  a  contaminant.  These  are  active 
antiferments,.  injurious  to  the  digestion. 

Properties. — Dextrose,  C6H12O6,  is  an  aldose — that  is,  it  has 
the  behavior  of  an  aldehyd  and  also  of  a  polyhydric  alcohol. 
From  a  sufficient  number  of  experimental  data  its  constitution 
has  been  worked  out  to  be  CH2OH  .  (CHOH)4 .  COH. 

The  ordinary  syrup  of  the  grocers  is  commonly  liquid  glucose 
made  from  starch,  decidedly  less  sweet  than  the  syrups  made 
from  cane-sugar.  Dextrose  by  evaporation  may  be  obtained  as 
hard  anhydrous  crystals,  or  another  sort  with  i  molecule  of  water 
of  crystallization.  It  is  less  soluble  and  less  sweet  than  cane- 
sugar,  and,  unlike  that  substance,  is  not  charred  when  warmed 
with  sulphuric  acid.  Its  aqueous  solutions  placed  in  the  polar- 
izing apparatus  are  dextrogyrous  (hence  the  name  dextrose)— 
that  is,  they  turn  the  ray  of  polarized  light  toward  the  right  hand, 

[ak=+52-5°  (P-  6l)- 

Dextrose,  like  the  aldehyds,  is  an  active  reducing  agent,  pre- 
cipitating the  metal  from  warm  solutions  of  the  salts  of  silver, 
gold,  and  platinum.  Its  reduction  tests  (Fehling's,  etc.)  are 
given  in  detail  in  another  place  (p.  602).  With  brewer's  yeast  its 
dilute  aqueous  solutions  readily  ferment  at  ordinary  temperatures, 
according  to  the  equation: 

C6H1206       =        2C2H60       +       2C02. 

Glucose.  Alcohol. 


436  ALIPHATIC    COMPOUNDS 

In  addition  to  the  principal  products,  ethyl  alcohol  and  car- 
bon dioxid,  a  trace  of  amyl  alcohol  is  formed  and  some  glycerin 
and  succinic  acid.  A  weak  solution  made  feebly  alkaline  and 
exposed  to  direct  sunlight  yields  the  same  products,  thereby 
showing  a  natural  tendency  to  break  up  this  way,  which  the  zymase 
of  yeast  accelerates.  With  phenylhydrazin  acetate  and  gentle  heat 
it  forms  fine  crystals  of  phenylglucosazone,  which  fuse  at  205°  C. 
(401°  F.)  (Plate  3,  a). 

When  oxidized  with  bromin  water,  dextrose,  CH2OH(CHOH)4- 
COH,  is  changed  to  monobasic  gluconic  acid,  CH2OH(CHOH)4- 
COOH.  More  powerful  oxidizers,  such  as  nitric  acid,  produce 
dibasic  saccharic  acid,  COOH(CHOH)4COOH,  the  last  oxida- 
tion derivative  of  dextrose  being  oxalic  acid.  In  the  body  the  COH 
group  of  glucose  is  not  oxidized  first  to  gluconic  acid,  but  the 
CH2OH  group  is  oxidized,  making  glycuronic  acid.  In  the 
laboratory,  by  reduction  of  saccharic  acid,  the  first  product  is 
glycuronic  acid,  COOH.  (CHOH)4COH,  a  normal  constituent  of 
the  body  which  is  eliminated  in  appreciable  amounts  by  the  urine 
after  full  doses  of  chloral,  camphor,  ajid  other  similar  substances. 
As  it  responds  to  the  copper  and  other  reduction  tests  like  glucose, 
it  is  the  source  of  a  fallacy  in  testing  the  urine  for  that  substance. 
Glycuronic  acid  does  not  ferment  with  yeast  nor  form  glucosazone 
with  phenylhydrazin  acetate.  The  free  acid  is  dextro-rotatory, 
but  its  usual  compounds,  the  conjugate  glycuronates,  are  levo- 
rotatory. 

Levulose  (C6H12O6)  (Fructose,  Fruit-sugar). — This  is  the 
portion  of  the  sweet  juices  of  fruits  and  of  honey  which  does  not 
crystallize;  or  does  so  with  great  difficulty.  In  composition  it  is 
a  ketose,  its  constitutional  formula  being  CH2OH(CHOH)3CO  .- 
CH2OH.  It  is  obtained,  with  an  equal  quantity  of  dextrose, 
when  cane-sugar  is  inverted  by  hydrolysis  with  dilute  mineral 
acids: 

C12H220U     +     H20     =      C6H1206     +     C6H1206 

Cane-sugar.  Dextrose.  Levulose. 

Its  name  is  derived  from  its  levorotatory  property,  turning  the 
polarized  ray  strongly  to  the  left,  as  shown  by  its  equation,  [a]D  = 
—  93°  (p.  61).  As  this  is  a  greater  angle  than  that  of  dextrose, 
inverted  sugar  is  slightly  levorotatory.  An  explanation  of  the 
optical  difference  is  found  in  the  stereochemical  formulas  of 
dextrose  and  levulose.  Dextrose  is  the  aldehyd  of  the  alcohol 
sorbite,  or  CH2OH(CHOH)4COH.  Levulose  is  the  ketone  of 
the  alcohol  mannite  or  CH2OH(CHOH)3CO  .  CH2OH  which 
shows  it  to  have  the  ketone  group  CO  and  in  addition  alcohol 
groups  at  both  ends.  By  oxidation  it  readily  yields  acids  and 


MONOSACCHARIDS  437 

ultimately  oxalic  acid.  Like  dextrose,  it  reduces  Fehling's  solu- 
tion, by  virtue  of  two  alcohol  groups,  and  forms  glucosazone  with 
phenylhydrazin.  It  is  less  fermentable  than  dextrose.  It  may 
be  recognized  by  the  following  reaction:  Heated  with  a  little  of 
a  weak  solution  of  resorcin  in  20  per  cent,  hydrochloric  acid,  it 
forms  a  red  color  and  precipitate. 

Both  dextrose  and  levulose  have  been  made  by  synthesis  from 
formaldehyd.  By  adding  milk  of  lime  to  an  aqueous  solution  of 
formaldehyd  jormose  is  obtained.  Formose  is  a  mixture  of  dif- 
ferent sugars  of  the  formula  C6H12O6,  apparently  polymerized 
formaldehyd: 

6CH20  C6H1206 

Formaldehyd.  Glucose. 

The  mixture  can  be  made  to  yield  both  dextrose  and  levulose. 

Galactose,  C6H12O6  or  CH2OH(CHOH)4COH,  is  formed  by 
the  hydrolysis  of  milk-sugar,  and  also  by  boiling  certain  gums  with 
dilute  sulphuric  acid.  It  crystallizes  in  prisms,  reduces  copper 
solutions,  is  strongly  dextrorotatory,  and  ferments  with  yeast. 
Oxidized  with  nitric  acid,  it  yields  mucic  acid. 

Inosite  (C6H12O6)  (muscle-sugar)  occurs  in  beans  and  peas,  the 
liquid  of  muscular  tissue,  and  in  various  organs  of  the  body. 
Traces  are  found  in  normal  urine,  the  amount  increasing  in  dia- 
betes and  in  some  cases  of  Bright's  disease.  Although  mentioned 
in  this  place  among  the  carbohydrates  because  of  its  sweet  taste, 
its  true  composition  is  hexahydroxy-benzol,  C6H6(HO)6.  It  does 
not  reduce  Fehling's  solution  nor  ferment  with  yeast,  but  under- 
goes the  lactic  and  butyric  fermentations. 

The  Pentoses  (C5H10O5). — All  the  pentoses  yet  studied  are 
aldoses  with  the  constitutional  formula  CH2OH(CHOH)3COH. 
Arabinose  is  a  product  of  the  action  of  dilute  sulphuric  acid  on 
cherry  gum;  xylose  (wood-sugar)  is  obtained  in  the  same  way 
from  wood,  gum,  and  straw.  Other  polysaccharids  than  gum, 
such  as  the  pentosanes  of  pears,  are  hydrolyzed  by  acids  or  by 
digestion  in  the  body  into  pentoses.  They  are  distinguished  from 
ordinary  sugars  by  the  large  amount  of  furfuraldehyd  yielded 
when  they  are  distilled  with  hydrochloric  acid.  The  human 
urine,  after  ingestion  of  certain  foods  containing  pentosanes, 
prunes,  cherries,  grapes,  and  beer,  and  also  in  certain  persons  as 
an  anomaly  in  their  metabolism,  contains  pentose,  and  this  may 
constitute  a  fallacy  in  testing  for  glucose  in  supposed  diabetics. 
Pentoses  respond  to  Fehling's  test,  form  osazones  with  phenyl- 
hydrazin, but  are  not  fermentable  with  yeast.  They  develop  a 
green  color  when  heated  with  a  saturated  solution  of  orcin  in 
hydrochloric  acid  (p.  606). 


438  ALIPHATIC    COMPOUNDS 

DISACCHARIDS 

The  empiric  formula  for  this  group  in  general  is  C12H22OU. 
Facts  are  lacking  from  which  to  establish  with  confidence  the 
constitutional  formulas  of  the  different  members.  They  appear 
to  contain  2  molecules  of  monosaccharids,  less  the  constituents 
of  water,  for  by  hydrolysis  with  dilute  mineral  acids  they  may  all 
be  resolved  into  2  hexose  molecules.  Thus: 

C12H220U         +          H20  2C6H1206. 

Taking  up  H2O,  cane-sugar  becomes  the  hexoses,  dextrose,  and 
levulose;  milk-sugar  is  converted  into  dextrose  and  galactose; 
maltose  into  2  molecules  of  dextrose.  A  convenient  division  is 
made  between  those  which  do  not  reduce  Fehling's  solution  (cane- 
sugar)  and  those  which,  like  the  hexoses,  possess  this  power 
(lactose  and  maltose). 

Cane=SUgar,  saccharum,  U.  S.  P.  (C12H22On)  (saccharose, 
sucrose),  exists  widely  distributed  in  the  sugar-cane,  sorghum, 
beet  root,  sugar  maple,  and  in  smaller  amounts  in  pineapples, 
sweet  berries,  and  other  fruits.  The  expressed  juice  is  freed  from 
vegetable  albumin,  decolorized,  evaporated  until  it  begins  to 
deposit  crystals,  and  then  in  a  centrifuge  the  crystals  of  sugar  are 
separated  from  the  mother-liquor.  The  brown  mother-liquor, 
called  molasses  or  treacle,  contains  50  per  cent,  of  sugar  that  does 
not  crystallize  until  various  impurities  are  removed. 

The  crystals  are  hard  four-sided  prisms,  soluble  in  one-third 
their  weight  of  water,  but  slightly  in  alcohol.  Rock  candy  is 
cane-sugar  crystallized  slowly  and  without  agitation  from  con- 
centrated solutions.  Beet-sugar  differs  from  cane-sugar  only  in 
being  lighter  in  equal  volumes.  Cane-sugar  melts  at  160°  C. 
(320°  F.),  and  on  cooling  the  liquid  solidifies  to  a  yellow,  glassy, 
amorphous  mass  called  barley-sugar.  Heated  to  a  higher  tem- 
perature, it  is  decomposed  into  glucose  and  levulose.  At  200°  C. 
(392°  F.)  it  loses  water,  and  is  converted  into  a  brown  mass  called 
caramel  or  burnt  sugar,  used  to  color  liquors  and  soups.  Cane- 
sugar  carbonizes  when  treated  with  warm  concentrated  sulphuric 
acid,  in  this  respect  differing  from  glucose. 

The  action  of  its  aqueous  solutions  upon  polarized  light  is 
the  basis  of  a  method  of  determining  the  degree  of  concentration. 
The  polarizer  used  for  this  purpose  is  called  a  saccharimeter, 
and  shows  the  deflection  to  the  right,  according  to  the  formula 
Ok  =+66.5°  (p.  61). 

After  being  hydrolyzed  by  boiling  with  acids  the  levulose 
product  twists  the  ray  in  the  reverse  direction  and  the  invert- 
sugar  becomes  levorotatory  to  a  slight  degree. 


DISACCHARIDS  439 

Cane-sugar  is  the  only  sugar  that  has  no  action  on  Fehling's 
solution,  though  it  reduces  potassium  permanganate.  Yeast  does 
not  excite  alcoholic  fermentation  in  it  directly,  but  after  some  time 
a  secondary  ferment  of  the  yeast,  invertase,  develops  from  it 
dextrose  and  levulose,  and  these  are  fermentable.  With  phenyl- 
hydrazin  it  does  not  yield  an  osazone,  differing  in  this  respect 
from  all  the  other  sugars.  With  the  hydroxids  of  strontium, 
calcium,  and  barium  it  combines  to  form  compounds  called 
saccharo  sates  or  sucrates.  The  compound  with  calcium  is  used 
in  medicine  under  the  name  of  saccharate  oj  lime. 

As  it  does  not  ferment  readily,  strong  cane-syrups  are  used  as 
preservatives  of  canned  fruit.  In  the  body  an  inverting  enzym 
for  cane-sugar  occurs  in  the  pancreatic  and  intestinal  juices, 
which  forms  glucose  more  readily  from  maltose  than  from  cane- 
sugar. 

Maltose,  C12H22OU,  with  dextrin  is  produced  from  starch-  by 
the  action  of  the  ferment  diastase  in  malted  or  germinated  grain: 

3(C6H1005)n   +   wH20   ==   wC12H22Ou   +   ^C6H1005 

Starch.  Maltose.  Dextrin. 

This  hydrolysis  is  accomplished  to  a  limited  extent  by  the 
action  of  dilute  sulphuric  acid  upon  cornstarch,  as  in  the  process 
for  manufacturing  commercial  glucose.  Ultimately  it  is  com- 
pletely converted  into  dextrose,  showing  that  it  is  an  anhydrid  of 
that  substance.  It  crystallizes  with  water  in  needles,  is  very 
soluble,  is  strongly  dextrorotatory  [a]D=  + 140.6°,  ferments 
readily  with  yeast,  and  reduces  Fehling's  solution.  It  forms  an 
osazone  with  phenylhydrazin  (Plate  3,  b).  If  the  enzym  maltase 
is  added  to  20-per  cent,  maltose  it  changes  only  86  per  cent,  to 
glucose;  the  equilibrium  is  reached  with  14  per  cent,  of  maltose 
left.  This  operation  is  reversed  when  the  same  enzym  is  added 
to  4o-per  cent,  pure  glucose.  It  builds  up  maltose  until  14  per 
cent,  is  made,  when  the  action  ceases  (Fig.  30). 

Milk=SUgar,  saccharum •  lactis,  U.  S.  P.  (C12H22On,  (lactose),  is 
found  in  the  milk  of  mammalia  in  the  average  proportion  of  4 
per  cent.  After  the  removal  of  butter,  fat,  and  casein  in  the 
manufacture  of  cheese,  the  remaining  liquid  yields,  on  evaporation, 
white  and  extremely  hard  crystals  of  lactose.  Compared  with 
cane-sugar  it  is  less  soluble  and  less  sweet.  WThile  it  reduces 
Fehling's  solution,  the  process  is  much  slower  than  when  glucose 
is  present.  It  rotates  the  polarized  ray  to  the  right,  [a]D  = 
+  52-53°  (P-  61).  With  yeast  it  does  not  ferment  directly  as 
glucose  does,  but  changes  very  slowly  into  alcohol  and  lactic  acid. 
When  this  change  occurs  in  mare's  milk,  kumyss  is  the  product; 


440 


ALIPHATIC    COMPOUNDS 


from  cows'  milk  kephir  is  obtained.     By  boiling  with  dilute  acids 
milk-sugar  is  hydrolyzed  and  breaks  up  into  dextrose  and  galactose: 


C12H220U 


H20      = 


C6H1206 

Dextrose. 


C6H1206 


Lactose.  Dextrose.  Galactose. 

With  nitric  acid  it  is  oxidized  to  mucic  acid  (Plate  3,  c). 


POLYSACCHARIDS 

These  have  the  composition  (C6H10O5)n,  but  the  constitution 
has  not  been  ascertained.  When  hydrolyzed  by  acids  they  be- 
tray a  much  higher  complexity  than  the  disaccharids,  splitting 
into  monosaccharids,  disaccharids,  and  dextrins.  Thus,  as 
stated  on  p.  439,  starch  is  decomposed  into  maltose  and  dextrin, 
both  of  which  have  a  very  high  molecular  weight.  The  poly- 
saccharids  are  colloids  and  non-dialysable,  both  physical  properties 
being  generally  associated  with  substances  of  a  high  molecular 
weight.  They  contain  monosaccharids  united  by  dehydration. 

Starch  (C6H10O5)n  (amylum,  U.  S.  P.)  is  found  widely  dis- 
tributed in  almost  all  the  tissues  of  plants,  but  is  most  abundant 
in  all  kinds  of  grain  and  in  nutritious  tubers,  such  as  the  potato. 


FIG.  80.— Potato  starch  (Wolf). 


FIG.  81.— Wheat  starch  (Wolf). 


The  sugar  and  gluten  are  converted  into  soluble  forms  by  rubbing 
and  steeping  in  warm  water,  leaving  starch  to  deposit  from  the 
washings  as  an  amorphous  mass.  When  dried  it  is  a  white  pow- 
der, tasteless,  odorless,  and  insoluble  in  cold  water,  alcohol,  and 
ether.  The  microscope  shows  starch  to  be  composed  of  granules 
marked  with  concentric  striations  and  a  cellulose  envelope  (Figs. 
80  and  81). 

The  granules  from  different  plants  may  be  identified  by  their 
characteristic  size,  shape,  and  structure.  When  boiled  in  water 
these  granules  swell  and  burst,  and  a  homogeneous  white  paste 


POLYSACCHARIDS  441 

or  jelly  is  formed.  Prolonged  boiling  causes  the  granulose  of  the 
cell  to  pass  into  solution,  leaving  the  cell  wall  or  cellulose  sus- 
pended. 

Experiment  i. — Stir  starch  in  cold  water  in  a  test-tube,  filter, 
and  test  the  nitrate  with  iodin.  It  does  not  turn  blue  because  the 
starch  has  not  dissolved. 

Experiment  2. — Boil  water  in  a  test-tube  and  add  a  small  quan- 
tity of  cold  starch  and  water.  It  forms  a  thin  paste  which,  when 
cooled,  turns  blue  with  iodin  (soluble  starch  or  amylodextrin). 

To  assimilate  the  starch  of  food  it  must  first  be  hydrolyzed  by 
dilute  acids  or  ferments  into  the  monosaccharids,  like  glucose. 
The  stages  of  conversion  can  be  noted  by  the  application  of  cer- 
tain tests  (Exps.,  p.  544). 

The  solution  of  starch  (amylodextrin)  yields  a  characteristic 
brilliant  blue  color  with  iodin,  which  disappears  on  heating  to 
reappear  on  cooling.  In  the  next  stage  (maltodextrin  and  erythro- 
dextrin)  iodin  gives  a  red  color.  In  the  third  stage  (achro-odextrin) 
iodin  gives  no  color.  At  last  maltose  and  dextrose  are  formed 
and  can  be  identified  by  Fehling's  solution.  In  any  sample  of 
starch  passing  through  these  changes  some  portions  of  the  inter- 
mediate products  are  present  at  all  periods,  as  the  process  is  con- 
tinuous until  complete. 

A  possible  explanation  of  the  progress  of  the  transformation 
may  be  found  in  the  hypothesis  that  the  starch  molecule  has  the 
great  weight  of  (C12H20O10)50.  Breaking  into  5  molecules  of 
(C12H20O10)10,  it  becomes  soluble;  hydrolyzed  in  successive  stages 
it  forms  the  series  of  dextrins  and,  simultaneously,  maltose  with 
each  series.  Cleavage  is  in  the  sense  of  this  equation: 

(C12H20010)IO     +     8(H20)     =     (C12H20010)2     +     8(C12H22On) 

Soluble  starch.  Achroodextrin.  Maltose. 

Dextrin  (C6H10O5)n  (British  Gum). — This  is  the  general  term 
applied  to  one  or  a  mixture  of  isomeric  substances  obtained 
as  transitional  forms  in  the  process  of  converting  starch  into  dex- 
trose. Besides  the  methods  given  above,  it  can  be  prepared  by 
heating  dry  starch  to  175°  C.  (347°  F.). 

In  appearance  and  properties  it  resembles  gum  arabic.  The 
commercial  article  is  a  yellowish  amorphous  powder,  which  in 
concentrated  aqueous  solution  is  mucilaginous  and  adhesive. 

Gums  (arabin  and  bassorin)  are  translucent  amorphous  sub- 
stances found  in  many  plants.  In  water  -  the  vegetable  gums 
swell  up  and  make  mucilages.  Boiled  with  dilute  sulphuric  acid 
they  yield  glucose. 

Qlycogen  (C6H10O5)10  (animal  starch)  is  a  polysaccharid  not 
found  in  plants,  but  largely  in  the  liver  and  other  tissues  and  cells 


442  ALIPHATIC    COMPOUNDS 

of  animals.  It  is  partly  derived  from  glucose  by  losing  the  ele- 
ments of  water,  a  dehydration  reversed  by  enzyms  in  the  muscles: 

ioC6H1206    fl±     (C6H1005)10     +      ioH20. 

Liver  tissue  minced  and  extracted  with  hot  water  yields  it  in  an 
impure  form.  The  albuminoid  material  may  be  precipitated  by 
acetic  acid  and  potassium  iodohydrargyrate,  and  the  nitrate, 
treated  with  alcohol,  deposits  the  pure  glycogen.  A  white  amor- 
phous powder,  without  odor  or  taste;  its  aqueous  solution  rotates 
the  polarized  ray  strongly  to  the  right,  [a]D=  + 196.6°.  With 
iodin  it  gives  a  wine  red  color  which  disappears  on  heating,  to 
reappear  on  cooling.  It  does  not  reduce  Fehling's  solution,  but 
is  converted  to  glucose  by  dilute  acids  or  certain  enzyms.  Like 
starch,  it  does  not  dialyze,  but  unlike  starch  it  is  readily  soluble  in 
cold  water. 

Cellulose  (C6H10O5)n  (Vegetable  Fiber).— In  all  plants  the 
woody  skeleton  and  cell  membrane  are  composed  mainly  of  this 
substance.  It  exists  almost  free  from  other  matter  in  cotton, 
wool,  linen,  and  hemp.  Swedish  filter  paper  is  cellulose  made 
pure  by  the  bleaching  and  washing  processes  to  which  the  raw 
fiber  has  been  subjected.  Though  isomeric  with  starch,  its 
molecular  weight  is  much  greater  than  that  of  starch.  Its  behavior 
denotes  that  10  hydroxyl  groups  enter  into  its  constitution.  Insol- 
uble in  water,  alcohol,  and  ether,  it  dissolves  in  Schweitzer's 
reagent  (ammoniacal  solution  of  cupric  oxid).  From  this  solution 
it  is  deposited  by  acids  as  a  gelatinous  mass  which  changes  by 
drying  to  a  grayish  powder. 

Cellulose  swells  and  is  slowly  dissolved  by  concentrated  sul- 
phuric acid.  This  solution  of  wood  fiber,  diluted  with  water  and 
boiled,  yields  dextrin  and  glucose.  Though  the  cellulose  itself 
is  not  digestible,  it  is  thus  transformable  into  valuable  foods. 

In  the  intestines  of  man  cellulose  of  vegetable  food  is  only  to 
a  limited  extent  dissolved:  most  of  it  passes  out  with  the  feces. 
In  the  herbivora  only  a  small  fraction  reappears  in  the  feces, 
showing  that  under  the  action  of  bacteria  or  enzyms  it  undergoes 
a  fermentation  into  soluble  products  that  are  absorbed. 

Parchment  paper  is  prepared  by  dipping  unsized  paper  for  a 
few  seconds  in  sulphuric  acid  diluted  with  an  equal  volume  of 
water.  It  is  next  washed  with  water  and  dilute  ammonia  and 
dried.  The  paper  is  greatly  toughened  without  losing  its  other 
properties.  It  is  substituted  for  parchment,  which  it  closely 
resembles. 

Guncotton  (Pyroxylin). — Pure  cotton  wool  treated  with  a 
mixture  of  nitric  acid,  i  part,  and  sulphuric  acid,  2  parts,  washed 


POLYSACCHARIDS  443 

and  dried,  is  converted  into  cellulose  hexanitrate,  C12H14(NO3)6O4. 
This  is  sometimes  called  trinitrocellulose,  C6H-O2(NO3)3.  This 
is  the  violently  explosive  guncotton,  insoluble  in  a  mixture  of  ether 
and  alcohol.  If  the  cotton  be  dipped  for  a  few  minutes  only,  less 
of  the  nitric  group  unites  with  it,  the  product  being  tetra-  and 
^ew/a-nitrates.  These  dissolve  in  a  mixture  of  alcohol  and  ether 
with  the  formation  of  collodion,  U.  S.  P.,  a  colorless  syrupy  liquid. 
By  the  evaporation  of  the  solvent  the  collodion  is  deposited  as 
a  transparent,  smooth,  contractile  film,  used  as  a  surgical  dressing 
or  as  a  basis  for  photographic  sensitive  films. 

Celluloid,  is  pyroxylin  mixed  with  camphor  and  coloring  sub- 
stances, and  shaped  by  pressure.  It  is  made  non-inflammable  by 
adding  sodium  or  ammonium  phosphate.  Elastic  collodion  (collo- 
dium  flexile,  U.  S.  P.)  contains  castor  oil  and  turpentine  to  render 
the  collodium  less  contractile  and  constringent.  It  is  used  as  a 
protective  covering  for  wounds  and  abrasions.  Styptic  collodion, 
U.  S.  P.,  is  flexile  collodium  made  astringent  by  the  addition  of  20- 
per  cent,  tannic  acid.  Cantharidal  collodion,  U.  S.  P.,  has  enough 
of  the  extract  of  cantharides  to  make  it  a  blistering  application. 

Qlucosids  are  natural  principles  of  plants  which  are  hydro- 
lyzed  by  alkalis,  mineral  acids,  or  certain  enzyms,  with  the  pro- 
duction of  a  sugar  and  another  substance  not  a  carbohydrate. 
The  sugars  formed  are  pentoses,  hexoses,  or  disaccharids.  The 
other  product  is  usually  a  derivative  of  the  benzene  series. 
Their  constitution  has  not  been  fully  established.  The  class 
includes  amygdalin,  convolvulin,  digitalin,  indican,  helleborin, 
salicin,  santonin,  sinigrin,  strophanthin,  etc.  Amygdalin  (C2H27- 
NOU)  occurs  in  bitter  almonds,  cherry,  laurel,  etc.;  it  is  hydro- 
lyzed by  the  enzym  emulsin  to  dextrose,  benzoic  aldehyd,  and 
hydrocyanic  acid  (p.  464).  Myronic  acid  or  sinigrin  occurs  in 
black  mustard  as  potassium  myronate  (KC10H18NS2O10)  and  is 
hydrolyzed  by  the  ferment  myrosin  in  cold  water  to  dextrose, 
mustard  oil,  and  potassium  sulphate  (p.  539). 

Phlorhizin  is  a  glucosid  in  the  bark  of  apple  and  pear  trees 
which  is  hydrolyzed  and  split  into  dextrose  and  phloretin.  When 
this  drug  is  given  it  causes  a  transient  glycosuria,  with  diminution 
of  the  normal  amount  of  glucose  in  the  blood.  Its  action  is  specific 
upon  the  kidneys;  their  soundness  is  tested  by  the  degree  of  excre- 
tion of  glucose  after  a  dose  of  phlorhizin. 

Carbohydrates  in  the  Body. — Uncooked  starch,  being  enclosed 
in  an  insoluble  envelop,  is  not  attacked  by  the  enzyms  of  diges- 
tion in  the  saliva,  but  passes  unchanged  as  far  as  the  intestine, 
where  part  of  it  is  decomposed  by  the  bacteria  and  part  digested. 
When  its  granules  are  burst  by  cooking  the  starch  is  set  free  and 
made  partly  soluble.  The  enzyms  of  the  saliva,  ptyalin  and 


444 


ALIPHATIC    COMPOUNDS 


maltase,  cause  hydrolytic  cleavage  into  soluble  starch,  dextrin,  and 
finally  maltose  (p.  441).  These  changes  go  on  in  the  mouth  and 
even  in  the  fundus  of  the  stomach  for  a  considerable  time  until 
gastric  acidity  is  pronounced,  when  the  portion  yet  undigested 
passes  into  the  intestine  to  meet  a  rapid  and  powerful  enzym, 
amylopsin  of  the  pancreatic  juice,  also  the  amylases  of  the  intes- 
tinal juices  and  invertase,  which  cause  hydrolytic  cleavage  in  the 
remainder  of  the  starch,  forming  maltose,  one  molecule  of  which 
is  split  by  an  enzym  in  the  epithelial  cells  of  the  stomach  and 
intestines  during  transmission,  to  form  two  molecules  of  dextrose. 

Cane-sugar  is  not  altered  by  ptyalin  nor  by  amylopsin,  but 
before  absorption  is  hydrolyzed  to  dextrose  and  levulose  either 
in  the  stomach  by  the  hydrochloric  acid  or  in  the  intestines  by 
the  invertase  or  by  the  epithelial  cells  while  passing  through  the 
walls.  Lactose  is  hydrolyzed  in  the  intestines,  reaching  the  blood 
as  dextrose. 

Fermentations  by  yeast  and  bacteria  occur  in  a  variable  portion 
of  the  dextrose  before  absorption.  These  are  typified  in  the 
following  equations: 

1.  C6H1206  =  2C02+2C2H5OH  (alcohol). 

2.  C2H5.  OH+02  =  H20  +  CH3.  COOH  (acetic  acid). 

3.  C6H12O6=2C3H6O3  (lactic  acid). 

4.  2C3H6O3=2CO2  +  4H  +  C3H7.  COOH  (butyric  acid). 


As  the  dextrose  in  the  portal  vein  passes  through  the  liver,  part 
of  it  is  dehydrated  to  glycogen  and  is  stored  up;  a  large  proportion 
passes  the  liver  and  is  distributed  throughout  the  body. 

In  the  muscles  part  is  dehydrated  and  stored  as  glycogen  and 
part  is  oxidized  to  lactic  acid  or  to  carbon  dioxid  and  water,  to 
give  energy.  Part  of  it  is  converted  and  stored  as  fat.  It  is 
probable  that  the  carbohydrate  excess  stored  in  the  liver  as  glyco- 
gen is  rehydrated  to  glucose  as  it  is  needed  by  the  body  at  large. 

Any  excess  of  glucose  in  the  blood  over  its  normal  amount, 
o.i  to  0.2  per  cent.,  is  excreted  at  once  by  the  kidneys,  causing 
glycosuria.  The  kidneys  do  not  form  the  sugar,  but  simply 
remove  it.  Among  the  cleavage  products  of  protein  metabolism 
are  the  sugars.  The  normal  pancreas  regulates  this  carbohy- 
drate and  protein  metabolism  of  other  organs.  When  pancreatic 
disease  arrests  or  perverts  this  influence,  either  more  protein  is 
converted  to  sugar  or  less  sugar  is  used  by  the  tissues.  This 
causes  excess  of  sugar  in  the  blood  and  its  separation  by  the  kid- 
neys. The  condition  is  known  as  pancreatic  glycosuria. 


THE    BENZENE    OR    AROMATIC    SERIES  445 

CYCLIC  COMPOUNDS 
THE  BENZENE  OR  AROMATIC  SERIES 

IN  the  foregoing  pages  consideration  has  been  given  to  the 
aliphatic  compounds — that  is,  those  of  the  paraffins,  or  the  fatty 
series,  and  especially  the  derivatives  of  methane,  CH4,  as  the  first 
of  two  main  divisions  of  organic  substances.  The  other  division 
is  known  as  the  cyclic  compounds  or  those  of  the  aromatic  series, 
or  the  derivatives  of  benzene,  C6H6.  Many  of  the  compounds 
belonging  to  the  fatty  series  can  be  prepared  directly  from 
petroleum,  or  derived  by  synthesis  from  it;  and  so  most  of  the 
aromatic  compounds  are  obtained  from  coal-tar  by  fractional 
distillation  and  laboratory  processes. 

As  benzene  is  the  lowest  member,  the  whole  group  is  called 
the  benzene  series,  just  as  the  other  group  is  called  the  methane 
series.  Certain  compounds  found  in  nature,  such  as  benzoic  acid, 
emit  peculiar  odors,  which  are  sometimes  agreeable.  Chemical 
studies  having  shown  that  these  can  be  derived  from  benzene, 
which  is  itself  aromatic,  the  term  has  been  applied  to  the  whole 
group. 

Coal=tar. — In  the  manufacture  of  coal-gas  the  coal  is  heated 
in  closed  retorts,  the  gas  and  other  volatile  products  distilling  out 
through  a  pipe,  leaving  solid  coke  behind.  When  the  hot  coal-gas 
is  cooled,  tar  is  one  of  the  condensed  substances,  the  coal-gas 
itself,  after  various  washings,  being  collected  in  gasometers,  from 
which  it  is  distributed  for  lighting  and  heating  purposes.  The 
coal-tar  is  a  thick  black  liquid,  at  one  time  treated  as  a  refuse 
material.  Modern  chemistry  has  extracted  from  it  a  large  number 
of  organic  compounds  of  the  greatest  medical  and  commercial 
value.  The  complex  mixture  of  more  than  forty  substances  in  the 
tar  is  subjected  to  fractional  distillation  at  four  temperatures, 
with  the  result  that  it  is  roughly  separated  into  five  fractions. 
By  refining  processes,  (i)  light  oil,  collected  up  to  170°  C.  (338°  F.), 
yields  the  hydrocarbons  benzene,  toluene,  and  xylene;  pyridin  and 
other  bases;  carbolic  acid  or  phenols.  The  (2)  carbolic  oil,  col- 
lected between  170°  C.  and  230°  C.  (446°  F.),  consists  principally 
of  carbolic  acid  and  naphthalene.  That  (3)  collected  between 
230°  C.  (446°  F.)  and  270°  C.  (518°  F.),  is  used,  under  the  name 
creosote  oil,  in  treating  wood  for  preservation.  It  contains  cresol, 
carbolic  acid,  naphthalene,  and  anthracene.  (4)  Green  oil,  coming 
off  above  270°  C.  (518°  F.),  contains  anthracene  and  certain 
hydrocarbons  solid  at  common  temperature.  The  residue  in 


446  CYCLIC    COMPOUNDS 

the  still  (5)  is  pitch,  employed  hot  as  a  varnish  to  protect  wood 
and  metal  work. 

All  of  these  bodies  contain  at  least  6  atoms  of  carbon,  and 
the  more  complex  aromatic  compounds  break  up  into  simpler 
ones  which  contain  at  least  6  atoms.  Through  many  changes 
the  aromatic  bodies  retain  the  group  of  6  carbon  atoms,  appar- 
ently joined  to  one  another  in  such  a  way  as  to  use  up  18  of  their 
combining  powers,  leaving  6  free.  Of  this  class  the  simplest 
and  most  important  illustration  is  benzene,  C6H6.  From  it  all 
the  compounds  of  this  class  may  be  derived  by  substituting  for  i 
or  more  of  the  6  hydrogen  atoms  those  of  other  elements  or  more 
complex  groups.  These  substances  may  be  made  in  numerous 
cases  to  yield  benzene  when  they  are  decomposed.  In  light  oil, 
the  first  crude  fraction  distilled  from  coal-tar,  are  found  4  hydro- 
carbons, homologous  with  benzene;  they  are  benzene,  toluene, 
xylene,  and  cumene.  From  these,  by  synthetic  process,  the  higher 
members  and  compounds  are  built  up.  In  the  following  table 
they  are  arranged  in  the  order  of  their  molecular  weight,  according 
to  the  general  formula,  CnH2n_6. 


BENZENE  HYDROCARBONS 

Benzene  or  Benzol,  C6H6. 

Toluene  or  Toluol,  C7H8,  or  Methyl-benzene  C6H5CH3. 

Xylene  or  Xylol,      C8H10,  or  Dimethyl-benzene      C6H4(CH3)2. 
Cumene  or  Cumol,  C9H,2,  or  Trimethyl -benzene      C6H3(CH3)3  ; 
Tetramethyl -benzene  C6H2(CH3)4. 

Benzene  (C6H6). — Having  removed  carbolic  acid  from  the 
oil  of  coal-tar  by  agitation  with  soda,  and  the  bases  by  sul- 
phuric acid,  distillation  yields  90  per  cent,  benzol.  By  further 
fractional  distillation  and  crystallization  of  the  benzene  in  a 
freezing  mixture,  the  commercial  article  is  prepared. 

Pure  benzene  in  small  quantities  is  prepared  by  heating  pure 
benzoic  acid  with  soda-lime: 

C6H,  .COOH  C6H6         +          C02. 

Benzoic  acid. 

Properties. — At  common  temperatures  benzene  is  a  colorless, 
mobile,  volatile  liquid  of  specific  gravity  of  0.880,  boiling  at  80.5° 
C.  (176.9°  F.).  Cooled  to  5.4°  C.  (41.7°  F.)  it  crystallizes.  It 
mixes  with  petroleum,  alcohol,  and  ether,  but  not  with  water. 
It  has  an  ethereal,  pleasant  smell;  is  highly  inflammable,  burning 


BENZENE    HYDROCARBONS  447 

with  the  luminous,  sooty  flame  indicative  of  richness  in  carbon. 
It  is  a  ready  solvent  for  iodin,  fats,  oils,  and  resins.  Its  chief  use 
is  in  the  manufacture  of  its  derivatives,  which  are  of  great  com- 
mercial importance. 

Toxicology. — A  narcotic  effect  is  produced  by  the  accidental 
inhalation  of  benzene  vapor  in  factories.  One  ounce  (30  c.c.) 
taken  by  the  stomach  caused  death  after  symptoms  such  as  head- 
ache, giddiness,  bluish  flush  of  the  face,  delirium,  convulsions, 
and  coma. 

Constitution  of  Benzene. — Benzene  behaves  so  differently 
from  other  hydrocarbons  we  have  studied  that  its  structure  must 
be  regarded  as  peculiar.  Like  the  paraffins,  it  is  extremely  stable, 
decomposing  with  difficulty  into  simple  compounds.  Boiling 
alkalis  do  not  affect  it,  and  only  very  slowly  is  it  oxidized  by  hot 
chromic  acid.  Chlorin  and  bromin  at  ordinary  temperatures 
gradually  attack  the  benzene  molecule,  forming  by  substitution 
chlorbenzene,  C6H5C1;  brombenzene,  C6H5Br;  dichlorbenzene, 
C6H4C12;  dibrombenzene,  C6H4Br2,  etc.  While  nitric  acid  does 
not  act  on  the  paraffins,  with  benzene  it  forms  nitrobenzene  by 
substitution  of  the  nitro  radical,  —  NO2,  for  an  atom  of  hydrogen: 

C6Htt     +     HO.NO2     =      C6H5NO2     +     HO  .  H 

Benzene.  Nitric  acid.  Nitrobenzene.  Water. 

These  substitutions  are  indications  that  C6H6  is  a  saturated 
compound.  It  is  not  as  fully  saturated  as  methane,  for  in  direct 
sunlight  it  forms  with  bromin  additive  compounds  as  high  as  hex- 
abromid,  C6H6Br6,  but  never  with  more  than  6  atoms.  When 
studied  very  closely  by  elaborate  experiments,  it  is  evident  that. all 
the  hydrogen  atoms  are  alike  in  their  relation  to  the  carbon  in  the 
compound.  Many  facts  combine  to  establish  the  following 
conclusions  as  their  most  reasonable  explanation: 

1.  The  benzene  molecule  is  symmetric. 

2.  The  6  carbon  atoms  form  a  closed  chain  or  hexagonal  ringy 
called  the  benzene  nucleus. 

3.  Each  carbon  atom  is  directly  united  with  only  i  atom  oj  hy- 
drogen. 

The  synthetic  method  of  preparing  benzene  is  by  heating 
acetylene  without  air,  when  3  molecules  are  converted  into  i 
molecule  of  benzene  by  polymerization: 

3C2H2  C6H6 

Acetylene.  Benzene. 

If  we  place  the  three  molecules  of  C2H2  side  by  side,  thus- 


448  CYCLIC    COMPOUNDS 

H 


H—  C     C—  H 

H—  C     C—  H 
-#> 
C 


and  suppose  that  each  C  atom  turns  a  valence  to  its  neighbor  C 
atom,  then  the  resulting  molecule  would  be  figured  thus: 

H 

i 

/\ 
H—  C      C—  H 

H—  C     C—  H 

\S 

C 

A 

This  graphic  formula  is  used  as  a  basis  to  represent  all  other 
facts  ascertained  concerning  benzene  and  its  derivatives,  which 
are  called  cyclic  because  of  this  ring.  When  the  ring  contains 
6  carbon  atoms  it  is  called  isocyclic;  if  less  than  6  carbon  atoms, 
then  it  is  called  heterocyclic. 

The  entire  theory  of  the  constitution  of  organic  compounds  is 
based  on  the  tetravalence  of  carbon.  The  above  hexagonal  ring 
shows  4  lines  drawn  from  each  carbon  atom,  2  of  the  4  lines 
meeting  2  other  lines  from  the  next  carbon  atom.  Thus  the  car- 
bon atoms  are  linked  by  i  or  2  valences  alternately.  The  ability 
to  form  additive  compounds  is  accounted  for  by  the  fact  that  each 
carbon  atom  has  i  affinity  not  actively  engaged.  By  substitution 
or  addition  to  this  ring  as  a  basis  an  infinite  variety  of  molecules 
are  constructed.  For  convenience  in  description  the  figure  of 
a  regular  hexagon  without  letters  is  used  to  represent  the  entire 
benzene  ring.  Used  alone,  it  stands  for  the  whole  molecule  C6H6; 
wrhen  other  atoms  or  groups  are  written  at  the  angles  they  are 
understood  as  being  substituted  for  an  atom  of  hydrogen.  Thus: 

COOH 


Toluene.  Nitrobenzene.  Benzoic  acid. 

C6H6(CH3)  C6H6(N02)  C4H6(COOH) 


BENZENE    HYDROCARBONS  449 

But  One  Mono  substitution  Product. — With  any  monovalent 
element,  such  as  bromin,  or  group,  such  as  —  NO2,  there  is  formed 
by  substitution  but  i  monobenzene  derivative.  Thus,  there  is 
but  i  brombenzene,  C6H5Br;  i  nitrobenzene,  C6H5 .  NO2;  i  ben- 
zoic  acid,  C6H5COOH,  etc.  The  only  possible  conclusion  is 
that  the  hydrogen  atoms  of  C6H6  do  not  differ  in  value. 

Three  Isomeric  Bisubstitution  Products. — With  derivatives  of 
benzene  containing  2,  3,  or  4  substituted  monovalent  elements  or 
groups,  there  are  3  isomeric  compounds,  corresponding  to  the 
three  possible  differences  in  the  relative  positions  of  the  radicals 
or  groups.  For  example,  there  are  3  different  dibrombenzenes, 
C6H4Br2;  3  dinitrobenzenes,  C6H4(NO2)2,  etc.  For  the  difference 
in  properties  of  the  3  isomers  there  is  but  one  explanation,  and 
that  is  based  upon  the  fact  that  any  hydrogen  atom  in  the  graphic 
benzene  formula  is  placed  symmetrically  in  relation  to  2  pairs  of 
hydrogen  atoms,  so  that  only  three  different  substitution  group- 
ings are  possible.  If  the  carbon  atoms  of  the  hexagon  are  num- 
bered as  the  hours  on  a  dial,  as  shown  below,  omitting  C  and  H, 


then  with  monovalent  bromin  it  is  possible  to  have  only  the  three 
different  positions  for  2  substituted  atoms,  as  shown  below: 


$r 

i :  2  Adjacent :  1:3  Unsymmetric  :  1:4  Symmetric : 

ortho-position.  meta-position.  para-position. 

Where  the  2  replacing  atoms  or  groups  occupy  adjacent  or 
consecutive  positions,  they  form  0r//*0-compounds  (orthos  =  straight), 
abbreviated  as  o-  or  i  12.  When  the  arrangement  is  unsymmetric, 
it  is  called  a  weto-compound  (meta  =  after),  abbreviated  m-  or 
1:3.  If  symmetric  in  position,  the  product  is  a  ^ara-compound 
(para  =  beside),  abbreviated  p-  or  i  :  4. 

When  3  or  4  atoms  of  hydrogen  are  displaced  by  as  many 
identical  atoms  or  groups,  3  isomers  result,  and  can  be  accounted 
for  if  their  constitutions  are  as  represented  in  the  following  for- 
29 


45° 


CYCLIC    COMPOUNDS 


mulas  for  the  3  tetrabrombenzenes,  using  the  simple  unnumbered 
hexagon: 

Br  Br 

Br 
Br 

br 

1:2:3:4  Adjacent :  1:2:3:5  Unsymmetric  :  1:2:4:5  Symmetric  : 

ortho.  meta.  para. 

When  the  simple  hexagon  without  letters  is  used  instead  of 
the  formula  C6H6,  the  conversion  into  a  molecular  formula  is 
made  by  writing  C6  for  the  hexagon,  allowing  i  hydrogen  atom 
for  each  unoccupied  corner,  and  writing  the  substituting  atoms  or 
radicals  last.  Thus: 

The  three  molecular  formulas  for  the  tetrabrombenzene,  the 
graphic  formulas  of  which  have  just  been  given,  would  be  written 
C6H2Br4.  To  distinguish  each  of  the  three  it  is  customary  to 
precede  the  formula,  or  to  append  in  parenthesis  below  the  line 
the  numbers  indicating  the  angles  taken  by  the  replacing  element: 

Ortho-C6H2Br4(1)2)3)4)  ;  meta-C6H2Br4(1)2i3)5)  ; 
para-C6H2Br4(1)2)4)5).     Or  they  may  be  written 
ortho- 1  :  2  :  3  :  4-  C6H2Br4;  meta-i  :  2  :  3    5-C6H2Br4; 
para- 1  12:4  :5~C6H2Br4. 

Another  illustration  is  seen  in  the  three  different  substances 
in  which  hydroxyl  groups  have  been  substituted  for  2  hydrogen 
atoms.  Careful  research  has  established  the  fact  that  their  con- 
stitutional formula  should  be  written: 

OH  OH  OH 


Ortho-  Meta- 

The  one  molecular  formula  for  all  three  is  C6H6O2,  but  this 
does  not  indicate  their  true  structure,  as  dihydr ox y benzenes.  A 
complete  conversion  of  the  graphic  hexagons  is  made  as  follows, 
the  common  name  being  given  after  each  formula: 

0-dihydroxybenzene   =  C6H4(OH)2,(1.2)  or  pyrocatechin. 
w-dihydroxybenzene  =  C6H4(OH)2a_3),  or  resorcin. 
/-dihydroxybenzene  =  C6H4(OH)2a_4),  or  hydroquinon. 


BENZENE    HYDROCARBONS  451 

General  Properties  of  Aromatic  Compounds.— The  members 
of  the  benzene  series,  like  those  of  the  methane  division,  form 
halogen  derivatives,  and  also  alcohols,  aldehyds,  ketones,  acids, 
nitro-  and  amido-compounds.  Reference  has  already  been  made 
to  their  characteristic  behavior  and  ready  reaction  with  nitric  acid. 
When  the  aromatic  nitro-compoiinds  are  reduced,  amido-com- 
pounds  are  produced,  containing  the  amido-group,  —  NH2.  Thus: 

C6H5.N02   +   6H   ==    C6H5.NH2   +   2H2O. 

Nitrobenzene.  Amidobenzene  or  anilin. 

When  the  amido-compounds  are  treated  with  nitrous  acid  in 
the  cold,  the  products  are  <fo'az0-compounds  and  not  alcohols,  as 
would  be  the  case  if  fatty  amins  were  so  treated.  The  diazo- 
compounds  are  unstable  bodies  in  which  the  hydrocarbon  radi- 
cal is  joined  to  a  double  atom  of  nitrogen,  having  one  free  affinity. 
Thus:  diazobenzene  is  C6H5 .  N2 .  OH. 

Among  the  indirect  derivatives  of  benzene  are  substances  like 
diphenyl,  C6H5— C6H5,  which  is  regarded  as  formed  by  the  union 
of  two  phenyl  groups,  resembling  in  this  respect  ethane  or  dimethyl, 
CH3  — CH3.  To  explain  the  structure  of  some  other  hydrocarbons 
it  must  be  assumed  that  combination  occurs  between  2  or  more 
closed  chains  or  nuclei  which  have  2  or  more  carbon  atoms  in  com- 
mon. These  substances  are  considered  (p.  471)  as  poly  nucleated 
compounds,  i.  e.,  containing  more  than  one  benzene  nucleus. 


Naphthalene.  Anthracene. 


Toluene  (C6H5  .  CH3)  (toluol,  methyl  benzene)  is  so  named 
because  it  can  be  obtained  by  dry  distillation  of  balsam  of  Tolu 
and  other  resins,  though  it  is  always  manufactured  from  coal-tar. 

It  is  a  mobile  liquid,  pleasant  smelling  and  inflammable,  does 
not  mix  with  water,  resembling  benzene,  but  having  some  prop- 
erties that  are  different,  due  to  the  methyl  group  in  its  composition. 
When  oxidized  the  CH3  of  the  methyl  is  changed  to  the  acid 
group  — CO  OH  and  water,  but  the  benzene  ring  is  unaltered. 

C6H5.CH3   +   30   ==    C6H5.COOH   +   H2O. 

Methyl  benzene.  Benzoic  acid. 

Xylene  (C6H4(CH3)2)  (xylol,  dimethylbenzene)  exists  in  the 
three  isomeric  forms,  given  below: 


452  CYCLIC    COMPOUNDS 

CH3 


Orthoxylene.  Metaxylene. 

These  three  varieties  exist  in  coal-tar  and  in  commercial  xylol, 
and  can  be  prepared  synthetically  from  toluene.  They  are  much 
alike  in  physical  properties,  being  liquids,  ethereal,  of  pleasant 
odor,  and  inflammable.  In  chemical  properties  there  are  certain 
marked  differences. 

Cumene  (C6H3(CH3)3)  (trimethylbenzene)  is  usually  obtained 
from  coal-tar.  It  is  the  third  of  the  homologues  of  benzene. 

Cymene  (C10H14  or  C6H4 .  CH3 .  C3H7)  (paramethyl-propylbenzene) 
is  an  important  pleasant-smelling  hydrocarbon  occurring  in  the 
ethereal  essences  of  thyme  and  many  other  plants.  It  is  easily 
prepared  from  camphor  with  phosphorus  pentoxid: 

C10HW0  C10HU         +         H20. 

Camphor.  Cymene. 

Its  relation  to  turpentine  is  shown  by  the  ease  with  which  it 
is  produced  when  that  substance  is  oxidized  by  being  heated  with 
iodin: 

C10H18         +         O  C10H14         +         H20. 

Turpentine.  Cymene. 

Terpenes.— The  hydrocarbon  terebenthene,  C10H16,  consti- 
tuting pure  oil  of  turpentine,  terebinthina,  U.  S.  P.,  is  classed  with 
its  numerous  isomers  as  terpenes.  They  may  be  regarded  as 
derived  from  cymene  by  the  addition  of  2  atoms  of  hydrogen. 
They  resemble  turpentine  chemically  and  physically,  and  are  the 
essential  constituents  of  many  volatile  oils,  such  as  lemon,  juniper, 
bergamot,  rosemary,  and  other  essences.  They  are  polymerized 
when  mixed  with  strong  sulphuric  acid;  are  converted  to  cymene 
by  the  halogens;  and  oxidized  to  several  acids  by  nitric  acid. 

Turpentine  not  being  water  soluble  is  given  internally  sus- 
pended in  emulsum  olei  terebinthince,  U.  S.  P.,  which  contains  gum 
acacia,  syrup,  oil  of  almond,  and  water.  Dose:  i  fl.  dr.  (4  c.c.). 
When  oil  of  turpentine  is  treated  with  nitric  acid  and  alcohol  it  is 
converted  to  terpin  or  turpentine  camphor,  a  diatomic  alcohol, 
C10H18(OH)2.  When  united  with  water  this  forms  terpini  hydras, 
U.  S.  P.,  in  the  form  of  colorless  crystals  of  bitterish  taste,  perma- 
nent and  water  soluble.  Dose,  as  an  expectorant:  3  to  10  gr. 
(0.2-0.6  gm.). 


BENZENE    HYDROXIDS  453 

Terebene,  U.  S.  P.,  is  obtained  by  the  action  of  sulphuric  acid  on 
oil  of  turpentine.  It  consists  chiefly  of  pinene,  C10H16.  It  is  a  yel- 
lowish liquid  of  thyme-like  odor  and  aromatic  taste,  forming 
resin  by  exposure  to  light.  It  is  sparingly  soluble  in  water,  freely 
so  in  alcohol  and  ether,  and  is  used  internally  as  an  expectorant, 
externally  as  an  antiseptic.  Dose:  5  to  10  ttL  (0.3-0.6  gm.). 

Stearoptens  (camphors)  are  solid  residues  formed  when  tur- 
pentine and  allied  substances  are  distilled  with  steam.  Camphor, 
U.  S.  P.,  a  dextrogyrate  ketone,  C9H16CO,  is  a  crystalline  solid  of 
characteristic  odor,  obtained  from  the  camphor  tree.  Artificial 
camphor,  C10H16HC1,  is  produced  by  the  direct  union  of  oil  of 
turpentine  and  hydrochloric  acid.  Menthol,  C10H20O,  is  a  solid 
stearopten  found  in  oil  of  peppermint.  Thymol,  U.  S.  P.,  C10HUO, 
is  a  solid  cymylic  phenol  found  in  oil  of  thyme.  It  is  crystalline, 
has  a  hot  taste  and  aromatic  odor.  Very  soluble  in  alcohol  and 
ether,  it  is  only  sparingly  so  in  water.  It  is  used  in  various  sur- 
gical preparations  as  an  efficient  and  agreeable  antiseptic.  Thy- 
molis  iodidum,  U.  S.  P.,  €3011240212,  dithymol  diodid,  aristol,  is  a 
red,  amorphous  powder  made  by  action  of  solution  of  iodin  in 
potassium  iodid  on  alcoholic  solution  of  thymol.  It  contains  45 
per  cent,  iodin  and  is  used  as  an  aromatic  substitute  for  iodoform 
in  surgical  dressings.  It  should  be  kept  in  amber-colored  bottles. 
Eucalyptol,  U.  S.  P.,  C10H18O,  is  a  camphoraceous  liquid  found  in 
oil  of  eucalyptus.  It  is  insoluble  in  water,  but  soluble  in  alcohol 
and  oils;  used  externally  as  an  antiseptic,  internally  for  lung 
diseases. 

BENZENE  HYDROXIDS   (Phenols) 

There  are  no  fatty  prototypes  to  the  phenols.  They  contain 
the  hydroxyl  group  substituted  necessarily  for  an  atom  of  hydro- 
gen of  the  benzene  nucleus  itself.  Thus,  ordinary  phenol  is 
C6H5 .  OH.  Their  constitution  is  different  from  that  of  a  primary 
alcohol  and  hence  when  oxidized  they  do  not  yield  an  aldehyd, 
and,  further  on,  an  acid,  nor  form  an  ester  with  an  acid,  as  does 
ethyl  alcohol. 

In  the  higher  homologues  of  benzene,  which  contain  hydrogen 
in  a  side  chain,  there  are  substances  which  contain  the  hydroxyl 
group  and  behave  on  oxidation  like  ethyl  alcohol.  These  are 
called  aromatic  alcohols  and  are  illustrated  in  benzyl  alcohol, 
C6H5 .  CH2OH,  derived  from  toluene,  C6H5 .  CH3,  by  the  substitu- 
tion of  —OH  for  an  H  of  —  CH3.  These,  when  oxidized,  form 
aromatic  aldehyds,  such  as  benzaldehyd,  C6H5 .  COH;  and  aro- 
matic acids,  such  as  benzoic  acid,  C6H5 .  CO  OH. 

The  two  kinds  of  aromatic  hydroxy-compounds  then  are 
(a)  phenols  and  (b)  aromatic  alcohols.  As  all  6  of  the  hydrogen 
atoms  of  the  benzene  nucleus  may  be  replaced  by  hydroxyl,  the 


454  CYCLIC    COMPOUNDS 

phenols  may  be  monohydric,  dihydric,  trihydric,  etc.,  according 
to  the  number  of  hydroxyl  groups  they  contain. 

Carbolic  acid,  C6H5 .  OH,  is  a  monohydric  phenol,  as  is  also 
cresol  or  hydroxytoluene,  C6H4(CH3)  .  OH.  Resorcinol  or  dihy- 
droxybenzene  is  a  dihydric  phenol,  and  phloroglucinol,  C6H3(OH)3, 
a  trihydric  phenol. 

Carbolic  acid  (C6H5 .  OH)  (phenol,  U.  S.  P.,  hydfoxybenzene) 
occurs  in  traces  in  the  urine,  in  the  form  of  sulphophenolate  of 
potassium,    KC6H3SO4.     This    compound    is    derived    from    the 
OH        protein  of  the  body.     The  sole  source  of  the  commer- 
cial article  is  coal-tar.      The  heavy  oil  is  treated  with 
sodium  hydroxid,  which  combines  with  the  phenol  and 
then,  on  the  addition  of  sulphuric  acid,  precipitates  in 
a   crude   state   as   an   oil.     By   more   complex   methods 
Phenol.        j£    can   kg    obtained   from   brombenzene,    nitrobenzene, 
anilin,  or  salicylic  acid. 

It  can  be  prepared  from  benzene  indirectly  by  the  following 
stages:  Nitric  acid  (HONO2)  making  nitrobenzene,  which  is 
reduced  to  amidobenzene  by  hydrogen:  this  by  the  action  of 
nitrous  acid  (HONO)  evolves  free  nitrogen,  retaining  hydroxyl. 

C6H6     —     C6H5N02     -*     C6H5.NH2     -+-     C6H5 .  OH 

Benzene.  Nitrobenzene.  Amidobenzene.  Phenol. 

Acidum  Carbolicum  Impurum. — To  purify  carbolic  acid 
further  treatment  is  necessary  with  lime  and  hydrochloric  acid, 
accompanied  with  successive  distillations.  Crude  phenol  is  brown 
red,  more  acid  than  the  pure,  and  has  a  stronger  odor,  due  to 
cresols. 

Properties. — The  volatilized  product  condenses  in  long  color- 
less or  faint  red  needles,  having  a  characteristic  odor,  and  when 
dissolved  in  much  water  a  caustic,  sweetish  taste.  It  turns  pink 
on  exposure  to  light  and  deliquesces  in  moist  air,  but  dissolves 
with  difficulty  in  15  parts  of  cold  water,  is  readily  soluble  in  boiling 
water,  alcohol,  ether,  glycerin,  chloroform,  and  the  oils,  but  not 
in  petroleum  and  benzin.  The  crystals  melt  at  43°  C.  (109.4°  F.), 
and,  agitated  with  10  per  cent,  of  water  or  glycerin,  they  become 
phenol  liquefactum,  containing  86.4  per  cent,  by  weight  of  absolute 
phenol.  This  is  the  most  convenient  form  for  dispensing  or 
for  other  uses.  It  is  a  protoplasmic  poison,  coagulating  albumin, 
and  hence  fatal  to  all  forms  of  life.  This  makes  it  a  potent  bac- 
tericide,  used  especially  in  surgery  for  destroying  the  germs  that 
infect  wounds.  Its  reaction  is  neutral  or  feebly  acid;  it  leaves  a 
greasy,  reddish  stain  upon  blue  litmus  paper.  With  strong  bases 
it  forms  carbolates  or  phenolates,  in  accordance  with  this  equation: 

C6H5OH    +    NaHO    =    C6H3ONa    +    H2O. 


BENZENE    HYDROXIDS  455 

With  alkaline  sulphates  it  forms  non-poisonous  salts  of  phenol- 
sulphonic  acid,  called  sulphophenolates: 

C6H5OH     +     Na2S04     =     NaC6H5SO4     +     NaHO. 

Phenol.  Sodium  Sodium 

sulphate.  sulphophenolate. 

Dose:  J  to  2  gr.  (0.03-0.13  gm.),  well  diluted.  Among  the 
official  preparations  are  glycerite  (i  part  to  4  of  glycerin);  oint- 
ment, 3  per  cent. 

When  the  crystals  are  triturated  with  the  following  substances 
a  liquid  or  soft  solid  product  is  obtained:  camphor,  chloral 
hydrate,  acetanilid,  lead  acetate,  menthol,  phenacetin,  resorcin, 
salol.  It  coagulates  collodion. 

Toxicology. — Owing  to  its  common  use  as  a  disinfectant  it  can 
easily  be  bought  by  the  suicide  at  any  druggist's.  Standing  about 
the  sick-room  as  an  amber-colored  oily  liquid,  it  has  been  often 
mistaken  for  castor  oil  or  alcoholic  drinks.  The  death-rate  from 
it  places  it  in  the  list  of  suicidal  poisons  next  to  opium  and  its 
preparations  and  alkaloids. 

Symptoms. — These  may  be  considered  under  two  heads:  Those 
due  to  the  local  effects,  and  those  that  are  systemic  in  character. 
Upon  the  mouth,  esophagus,  stomach,  and  intestines  it  acts  as  an 
energetic  corrosive  poison.  When  absorbed  it  quickly  arrests 
normal  action  in  the  nervous  system,  and  causes  death  by  paral- 
ysis of  the  respiratory  and  cardiac  centers. 

If  some  of  it  touch  the  skin  about  the  mouth,  it  causes  burning, 
tingling,  and  numbness,  followed  by  a  white  eschar.  The  cor- 
roded skin  tissue  separates  in  a  few  days  and  the  white  spot  is 
succeeded  by  a  brown  stain.  When  it  is  swallowed  the  patient 
complains  of  a  burning  pain  in  the  mouth,  throat,  and  stomach, 
with  or  without  retching  and  vomiting.  There  is  distention  of 
the  abdomen  and  a  strong  odor  of  carbolic  acid  on  the  breath. 
The  remote  systemic  effects  are  the  same  whether  the  point  of 
absorption  be  the  skin,  the  lungs,  an  open  wound,  the  stomach, 
or  other  body  cavities.  The  symptoms  are  muscular  twitchings, 
weakness,  pallor,  nausea,  clammy  skin,  headache,  giddiness,  de- 
lirium, thready  and  rapid  pulse,  irregular  breathing.  Lividity, 
coma,  rarely  convulsions,  imperceptible  pulse,  and  halting  respi- 
ration usher  in  the  final  scene.  In  the  meantime  the  urine  is 
albuminous  and  bloody. 

The  greater  part  of  the  phenol  changes  by  contact  with  the 
sulphates  in  the  body  to  sulphophenolates  and  the  simple  sul- 
phates disappear  from  the  urine.  The  normal  ratio  of  the  simple 
sulphates  of  the  urine  to  the  conjugate  sulphates  is  as  10  :  i.  A 
portion  of  the  phenol  is  changed  to  phenol-glycuronic  acid  and  is 


456  CYCLIC    COMPOUNDS 

eliminated  as  harmless  conjugate  alkali  salts.  A  considerable 
portion  is  oxidized  to  the  dihydroxybenzenes,  pyrocatechol,  and 
hydroquinol.  These  also  form  conjugate  sulphates.  In  the 
urine  they  oxidize  further  to  quinon  (C6H4O2),  a  dark  greenish 
or  black  substance. 

Fatal  Dose. — Though  15  gr.  (i  gm.)  would  cause  dangerous 
symptoms  when  taken  by  the  stomach,  a  fatal  result  is  not  likely 
unless  60  gr.  (4  gm.)  have  been  taken.  Recovery  has  ensued 
after  i  fl.  oz.  (30  c.c.)  has  been  swallowed.  Absorbed  from  a 
wound,  from  the  rectum  or  uterus,  15  gr.  (i  gm.)  would  probably 
kill. 

Fatal  Period. — Large  doses  or  external  application  to  open  cuts 
may  destroy  life  in  ten  minutes.  Usually  death  is  not  delayed 
beyond  two  hours,  though  there  are  cases  where  death  has  not 
occurred  for  several  days. 

Treatment. — The  local  anesthesia  prevents  the  action  of  ordi- 
nary emetics.  A  liberal  dose  of  whisky  or  alcohol  is  often  given 
as  a  diluent.  It  should  be  followed  by  the  introduction  of  the  soft 
stomach-tube  and  washing  with  syr.  calcis,  or  sodium  sulphate 
until  the  contents  of  the  stomach  lose  their  peculiar  odor.  Sodium 
sulphate  forms  the  relatively  harmless  sodium  phenol-sulphonate. 
Dependence  should  not  be  placed  on  alcohol  as  an  antidote. 

If  carbolic  acid  be  applied  to  the  skin,  the  mucous  membrane, 
or  open  wound,  and  quickly  followed  by  a  lotion  of  alcohol,  the 
corrosive  action  does  not  occur,  and  there  are  no  constitutional 
symptoms.  Some  of  this  controlling  action  may  be  the  effect  of 
prompt  dilution  with  a  perfect  solvent.  It  is  not  unlikely  that 
alcohol,  as  a  solvent,  causes  the  molecule  to  dissociate  in  different 
ions  from  those  that  form  in  aqueous  solution.  If  ferric  chlorid 
be  added  to  the  solution  in  water,  a  violet-colored  reaction  ap- 
pears; with  the  alcoholic  solution  it  is  brownish.  If,  however, 
water  be  added  to  the  mixture  with  alcohol,  the  brownish  liquid 
changes  to  violet.  If  the  alcohol  and  carbolic  acid  be  allowed 
to  remain  in  the  stomach,  osmotic  flow  of  water  dilutes  the  alcohol, 
and  in  a  few  minutes  absorption  begins  and  the  effects  are  those 
of  a  poisonous  aqueous  solution.  To  obviate  this  danger  the 
lavage  must  remove  the  poison  as  soon  as  alcohol  has  been  given. 
The  antidotes  of  approved  value  are  sodium  sulphate,  raw  eggs, 
milk,  and  saccharate  of  lime. 

For  the  coma  and  cardiac  depression  benefit  may  follow  alter- 
nations of  hot  and  cold  affusions  and  the  administration  of  hypo- 
dermic injections  of  atropin  or  strychnin.  For  failure  of  breathing 
resort  should  be  had  to  artificial  respiration. 

Postmortem  Appearances. — The  corroded  spots  about  the  lips, 
and  the  mucous  lining  of  the  mouth  and  esophagus  are  white  and 


BENZENE    HYDROXIDS  457 

corrugated.  The  stomach  mucous  membrane  is  hardened, 
white  in  patches,  wrinkled,  denuded  in  parts,  showing  the  red 
inflamed  structure  beneath.  Hemorrhagic  points  show  where 
blood  has  been  poured  into  the  gastric  contents. 

Like  changes  appear  in  the  duodenum.  The  characteristic 
odor  of  carbolic  acid  is  discernible  in  the  body,  in  the  fluid  of 
the  ventricles  of  the  brain,  and  in  the  urine.  The  urine  is  dark- 
greenish  and  shows  little  reaction  to  barium  chlorid,  the  sulphates 
being  conjugate  with  phenol. 

Tests. — i.  The  odor  is  characteristic. 

2.  Carbolic  acid  coagulates  albumin  and  also  the  clear  collo- 
dion solution. 

3.  A  trace  of  ferric  chlorid  gives  an  amethystine-blue  color  to 
aqueous  solutions  of  carbolic  acid.     This  test  is  interfered  with 
by  alcohol,  ammonia,  the  mineral  acids,  and  excess  of  ferric  chlorid, 
all  of  which  prevent  the  full  development  of  the  reaction.     Cre- 
osote turns  ferric  chlorid  brown  and  green. 

4.  Strong  bromin   water  added  to   weak   carbolated  solutions 
precipitates  white  crystals  of  tribromphenol. 

5.  When  boiled  with  Milton's  reagent?  made  fresh,  solutions 
of  carbolic  acid  turn  red.     If  the  change  does  not  occur,  it  may 
require  the  addition  of  a  few  drops  of  nitric  acid.     The  same 
reaction  is  produced  by  other  phenols  and  the  proteins,  as  is  shown 
when  pieces  of  dry  albumin  or  dry  bread  are  boiled  in  Millon's 
reagent;  they  turn  dark  red. 

This  reaction  always  denotes  the  OH  group  attached  to  the 
benzene  ring  (oxyphenyl).  Given  by  the  proteins  it  indicates  in 
them  the  presence  of  this  same  combination  existing  in  the  cyclic 
compound  tyrosin  (p.  500). 

6.  A  solution  of  carbolic  acid  is  gently  warmed  with  a  small 
quantity  of  ammonia  water  and  a  few  drops  of  solution  of  chlo- 
rinated lime.     A  blue  color  is  produced,  which  changes  to  red  on 
being  acidulated.     If  the  blue  color  fade,  it  may  be  restored  by 
the  addition  of  more  of  the  chlorinated  lime. 

Detection. — A  portion  of  the  blood  or  the  liver  is  digested  for 
one  hour  with  dilute  sulphuric  acid  (2  per  cent.).  After  straining, 
the  liquid  is  mixed  with  dilute  alcohol  (i  to  3)  and  filtered.  Having 
treated  30  c.c.  of  this  with  a  few  drops  of  ammonia,  it  is  added  to 
a  reagent  prepared  as  follows:  To  20  c.c.  of  a  solution  of  ani- 
lin  containing  3  drops  to  100  c.c.  of  water,  add  sodium  hypo- 
chlorite. sufficient  to  make  a  brown  color.  When  the  extract  from 

1 A  mixture  of  mercuric  and  mercurous  nitrates  containing  some  free  nitrous  acid, 
made  by  adding  5  c.c.  of  fuming  nitric  acid  to  0.5  c.c.  of  mercury.  The  mercury 
must  dissolve  without  boiling  and  the  solution  is  then  diluted  with  two  volumes 
of  water,  and  after  several  hours  decanted.  It  does  not  keep  long. 


458  CYCLIC    COMPOUNDS 

the  liver  or  blood  is  added  to  this  reagent  a  permanent  blue  color 
indicates  the  presence  of  carbolic  acid. 

The  urine  is  titrated  with  BaCl2  to  see  if  the  simple  sulphates 
are  less  than  normal.  It  is  then  filtered  from  BaSO4  and  boiled 
with  HC1  to  break  up  the  sulphophenolates.  Tested  again  with 
BaCl2,  if  a  heavier  precipitate  falls,  there  is  excess  of  sulpho- 
phenolates, due  to  phenol  (p..  589). 

Phenolsulphonic  acid  (C6H4(OH)  .  SO3H)  (sulphocarbolic  acid) 
is  formed  when  phenol  is  dissolved  in  concentrated  sulphuric  acid 
(for  Sulphonic  Acids  see  p.  415): 

C6H5OH    +    H2S04    =    C6H4(OH) .  S03H    +    H2O. 

It  is  a  syrupy  liquid  having  a  red  color  and  feeble  odor,  and 
is  freely  soluble  in  water.  It  behaves  as  a  monobasic  acid,  forming 
sulphocarbolates  of  sodium,  potassium,  and  other  metals.  The 
acid  and  its  salts  prevent  fermentation,  destroying  low  forms 
of  animal  and  vegetable  life,  and  are  valued  in  medicine  as  anti- 
septics, being  less  irritating  and  poisonous  than  carbolic  acid. 
The  commercial  aseptol  or  sozolic  acid  is  a  3o-per  cent,  solution 
of  0-phenolsulphonic  acid  in  water,  used  diluted  to  10  per  cent,  as 
an  antiseptic. 

After  the  ingestion  of  phenol  it  is  eliminated  by  the  urine  as  a 
potassium  sulphophenolate  (KC6H5SO4),  a  conjugate  or  ethereal 
sulphate. 

Sodii  phenolsulphonas,  U.  S.  P.,  C6H4(OH)SO3Na,  is  a  white 
crystalline  salt,  used  locally  as  an  antiseptic,  and  internally  in 
fermentative  dyspepsia.  Dose:  10  to  30  gr.  (0.6-2  gm.). 

Zinci  phenolsulphonas,  U.  S.  P.,  Zn(C6H5O4S)2  +  8H2O  occurs 
in  colorless,  tabular  crystals  used  to  make  astringent  solutions. 

Ichthyol  is  the  ammonium  salt  of  a  complex  ichthyosulphonic 
acid  having  the  formula  C28H36S3O6(NH4)2.  It  is  prepared 
from  a  mineral  pitch  found  in  the  Tyrol,  containing  fossil  fishes. 
It  is  a  dark  brown  thick  liquid  with  an  unpleasant  smell,  soluble 
in  water,  oils,  and  glycerin.  Applied  locally,  it  is  analgesic  and 
antiphlogistic.  It  is  incompatible  with  acids,  alkalis,  and  alkaloids. 

Trinitrophenol  (C6H2(NO2)3.  OH)  (Picric  Acid).— When  phe- 
nol is  treate'd  with  dilute  nitric  acid  it  is  converted  into  ortho- 
and  ^am-nitrophenol,  which  separate  as  a  dark  brown  oil  or 
resinous  mass.  If  this  or  a  solution  of  phenol  itself  be  gently 
heated  with  a  few  drops  of  nitric  acid,  3  groups  of  NO2  are  taken 
up,  the  liquid  turns  yellow,  and  on  cooling  crystals  of  picric  acid 
separate. 

The  constitution  of  trinitrophenol  is  represented  by  the  for- 
mula: 


BENZENE    HYDROXIDS  459 

OH 

<\ 

NO/        \N02 


It  is  the  yellow  substance  formed  by  the  action  of  concentrated 
nitric  acid  on  woolen  and  silk  fabrics,  albumin,  bread,  and  other 
nitrogenous  animal  matter,  indigo,  resins,  leather,  etc. 

This  xanthoproteic  reaction  always  indicates  the  presence  of 
the  benzene  ring,  but  not  necessarily  with  the  OH  group  attached, 
as  in  phenol.  In  the  proteins  are  found  not  only  tyrosin,  but 
phenylalanin,  both  of  which  give  this  yellow  color  with  nitric  acid, 
due  to  trinitrophenol  (picric  acid).  It  is  crystalline,  odorless, 
intensely  bitter,  markedly  acid,  and  slightly  soluble  in  cold,  but 
more  easily  so  in  hot  water.  It  has  the  properties  of  a  monobasic 
acid,  readily  decomposing  carbonates  and  forming  salts.  Potas- 
sium picrate,  C6H2(NO2)3 .  OK,  like  the  sodium  and  ammonium 
compounds,  is  a  yellow  crystalline  substance,  explosive  under 
the  action  of  heat  or  percussion.  Picric  acid  itself  burns  quietly 
when  ignited  with  caution,  but  under  percussion  or  sudden  heat 
explodes  violently.  It  is  used  as  a  yellow  dye  for  silk  and  wool. 
It  is  a  valuable  precipitant  for  albumin  in  Esbach's  test,  and  for 
the  alkaloids.  Heated  with  glucose  in  alkaline  solutions  it  pro- 
duces a  deep  red  color.  Sometimes  it  is  used  as  an  adulterant 
for  beer,  because  of  its  bitter  taste  and  yellow  color. 

Toxicology. — Picric  acid  is  sometimes  applied  to  the  skin  in 
the  treatment  of  skin  diseases  and  burns.  Absorbed  from  the 
skin  or  taken  internally  it  may  cause  poisonous  symptoms. 
Locally  it  irritates  the  skin,  causing  eczema;  taken  by  the  mouth 
the  mucous  membrane  is  irritated,  by  virtue  of  the  necrosis  due  to 
the  precipitation  of  the  albumin  in  the  tissues.  There  are  vomiting 
of  yellow  matter,  abdominal  pain,  and  diarrhea  with  yellow  stools. 
Without  bile,  the  urine  becomes  red-brown  owing  to  the  presence 
of  picraminic  acid.  The  blood  corpuscles  decompose  and  form 
methemoglobin.  The  eyes  turn  yellow  and  the  skin  itches,  as  in 
jaundice.  Great  weakness,  stupor,  and  convulsions  precede 
collapse. 

Fatal  Dose. — Poisoning  has  followed  30  gr.  (2  gm.),  but  recov- 
ery has  occurred  after  90  gr.  (6  gm.). 

Treatment. — The  stomach  should  be  thoroughly  washed  out, 
and  the  bowels  evacuated  by  enemata.  The  antidotes  are  proteins, 
as  in  raw  eggs  and  milk.  Glucose  reduces  the  picric  acid  to  a  less 
injurious  substance,  and  may  be  given  freely. 

Tests. — Having  acidulated  the   material   with  sulphuric  acid, 


460  CYCLIC    COMPOUNDS 

ether  is  shaken  with  it  to  extract  the  picric  acid.  The  residue 
after  evaporation  is  dissolved  in  water,  and  a  thread  of  cotton  and 
one  of  wool  placed  in  it.  It  is  then  acidified  and  warmed.  The 
cotton  is  not  dyed,  but  the  wool  stains  yellow,  yielding  the  color 
when  immersed  in  alkaline  solutions.  When  an  alkaline  solution 
of  it  is  warmed  with  potassium  cyanid  a  blood-red  color  is  produced. 

Cresol  (C6H4(CH3)  .  OH)  (Cresylic  Ac-ids,  Hydroxytoluenes).— 
The  three  next  homologues  of  phenol  are  the  ortho-,  meta-,  and 
para-cresols,  occurring  in  coal-tar  and  separable  from  it  by  frac- 
tional distillation.  They  resemble  phenol  as  poisons  of  feeble 
solubility  in  water,  in  forming  compounds  with  potassium  and 
sodium,  and  in  giving  the  bluish  color  with  ferric  chlorid. 

Liquor  cresolis  compositus,  U.  S.  P.,  is  a  solution  of  cresol  in 
a  soapy  liquid  made  with  linseed  oil  and  potassium  hydroxid. 
It  is  miscible  with  water  in  all  proportions,  and  is  a  reliable  and 
convenient  disinfectant  for  the  hands  and  instruments  in  the 
proportion  of  one  part  to  twenty  of  warm  water. 

Creolin  is  a  black  syrupy  antiseptic,  containing  a  number  of 
aromatic  substances,  chiefly  cresols.  It  is  less  poisonous  than 
carbolic  acid.  Dose:  5  to  15  min.  (0.3-1  gm.). 

Lysol  is  an  oily  liquid,  saponified  by  boiling  tar,  oils,  fat,  and 
resin  with  alkali.  It  is  an  impure  paracresol  containing  soap, 
soluble  in  water;  antiseptic  and  less  poisonous  than  carbolic  acid. 

Creosote  is  a  complex  mixture  of  phenol,  cresol,  guaiacol, 
C7H8O2,  creosol,  C8H10O2,  phlorol,  C8H10O,  and  other  aromatic 
compounds  produced  by  distillation  of  wood-tar.  It  is  an  oily 
liquid  of  peculiar  odor  and  burning  taste;  colorless  when  fresh, 
but  turning  brownish  on  exposure  to  light.  It  is  often  adulterated 
with  carbolic  acid,  which  it  resembles  in  being  an  antiseptic  and 
a  powerful  irritant  poison.  It  is  used  as  a  local  application  for 
toothache  and  a  caustic  for  warts.  It  is  to  be  distinguished  from 
carbolic  acid  in  its  feebler  solubility,  in  not  crystallizing  on  cool- 
ing, in  not  coagulating  the  official  collodium,  and  in  giving  with 
ferric  chlorid  a  transient  brownish,  and  not  a  bluish  coloration. 

Toxicology.— The  poisonous  effects  are  much  like  those  of 
carbolic  acid  and  guaiacol. 

Dihydric  Phenols  (C6H4(OH)2).— The  three  isomeric  dihy- 
droxybenzenes  are  well  known  and  have  much  importance  under 
the  names  pyrocatechol,  resorcinol,  and  hydroquinol.  Their 
respective  formulas  are  given  in  another  place  (p.  450). 

Pyrocatechin,  Catechol,  0-C6H4(OH)2,  is  eliminated  in  traces 
by  the  human  urine,  having  entered  the  circulation  as  a  product  of 
intestinal  putrefaction.  It  also  occurs  in  the  drug  catechu.  It 
can  be  prepared  by  fusing  phenolsulphonic  acid  with  potash. 

It   is   a   colorless   crystalline   substance,   soluble   in   water.     In 


BENZENE    HYDROXIDS  461 

weak  solution  it  can  reduce  Fehling's  solution,  and  hence  create 
a  fallacy  in  testing  for  glucose  in  the  urine.  To  detect  it  in  the 
urine  a  considerable  quantity  of  that  fluid  must  be  boiled  with 
hydrochloric  acid  and  then  extracted  with  ether.  The  residue 
after  evaporation  is  dissolved  in  water,  and  this  solution  gives 
with  ferric  chlorid  a  dark-green  coloration  which,  on  the  addition 
of  sodium  bicarbonate,  changes  to  violet  and  later  to  red. 

This  green  color  with  ferric  chlorid  is  given  with  all  the  dihy- 
droxybenzenes.  The  preparation  extracted  from  the  supra- 
renal gland,  called  adrenalin,  yields  the  same  reaction,  showing 
the  presence  of  catechol  as  a  component  of  the  active  principle. 
Its  constitution  is  believed  to  be  represented  by  the  formula: 

OH 
OH 


CHOH  .  CH2 .  NHCH3 


Guaiacol,  U.  S.  P.,  C6H4 .  OH  .  OCH3,  methyl-pyrocatechin,  is 
a  crystalline  solid  contained  in  the  tar  of  beechwood,  from  which 
it  is  obtained  by  the  fractional  distillation  of  creosote.  In  absolute 
guaiacol  it  occurs  as  an  oily  liquid  of  aromatic  odor,  slightly  sol- 
uble in  water,  freely  so  in  alcohol  and  ether.  It  is  used  in  med- 
icine. Dose:  3  to  15  gr.  (0.2-1  gm.).  Its  pharmaceutic  com- 
pounds are  the  carbonate,  benzoate,  iodid,  and  salicylate. 

Resorcin  (C6H4(OH)2)  (resorcinol,  m-dihydroxybenzene)  is  pre- 
pared by  the  action  of  fused  potash  on  benzene-w-disulphonic 
acid.  It  can  also  be  obtained  by  dry  distillation  of  extract  of 
Brazil  wood,  and  by  melting  with  caustic  potash  various  resins, 
such  as  galbanum.  Its  structure  has  been  referred  to  previously 

(P-  45°)- 

It  is  a  crystalline,  colorless  (turning  red  on  exposure),  sweetish 
substance,  freely  soluble  in  water,  alcohol,  and  ether.  It  is  odor- 
less and  antiseptic.  Its  aqueous  solution  turns  a  violet  color  with 
ferric  chlorid.  Under  the  name  Boas'  reagent  (p.  549)  an  alco- 
holic solution  of  resorcin  and  cane-sugar  is  used  as  a  delicate 
test  for  free  hydrochloric  acid. 

When  the  resorcin  is  heated  with  phthalic  anhydrid  in  a  dry  tube, 
a  reddish  mass  is  formed  which,  when  dissolved  in  soda,  gives  a 
brownish  solution.  Added  to  water,  this  gives  a  beautiful  red 
color  with  a  yellow-green  fluorescence.  This  shows  the  presence 
of  fluorescein  (resorcin-phthalein),  C20H12O5,  an  important  dye- 
stuff,  from  which  is  manufactured  its  sodium  salt,  uranin, 
C20H10O5Na2,  another  valuable  dye.  When  fluorescein  is  treated 


462  CYCLIC    COMPOUNDS 

with  bromin,  4  atoms  of  hydrogen  in  the  resorcin  nuclei  are  dis- 
placed by  bromin,  forming  eosin,  a  deep  red  dye  with  green  fluor- 
escence. Its  potassium  salt  is  a  brownish  powder  which  stains 
tissues  a  beautiful  pink. 

The  medical  effects  of  resorcin  are  those  of  phenol.  It  is  used 
externally  in  skin  diseases  and  in  surgical  dressings.  By  absorp- 
tion from  the  skin  it  may  cause  the  toxic  nervous  symptoms  of 
phenol. 

Dose  of  resorcin  for  seasickness:  2  gr.  (0.13  gm.)  every  two 
hours;  for  antipyretic  effects:  15  to  30  gr.  (1-2  gm.).  Its  incom- 
patibles  are  albumin,  alkalis,  antipyrin,  acetanilid,  exalgin,  cam- 
phor, menthol,  urethan,  ferric  chlorid,  and  spts.  astheris  nitrosi. 

Hydroquinol  (C6H4(OH)2)  (quinol,  p-dihydroxybenzene)  is  a 
crystalline  substance,  readily  soluble  in  water,  and  used  in  photog- 
raphy. It  is  an  antipyretic  in  doses  of  15  gr.  (i  gm.). 

Pyrocatechol,  resorcinol,  and  hydroquinol  are  reducing  agents, 
taking  oxygen  from  other  compounds  and  in  the  presence  of  alkalis 
even,  from  the  air,  turning  to  dark-green  quinone  (C6H4O2). 
Hydroquinol  is  the  most  active  in  this  respect. 

Trihydric  Phenols  (C6H3(OH)3).— The  three  trihydric  iso- 
mers  possible  in  theory  are  all  known;  their  constitutions  are 
represented  by  the  three  formulas: 

OH  OH  OH 

^,OH  f\  f     \OH 

OH 


Pyrogallol.  Phloroglucinol.  Hydroxyhydroquinol. 

1:2:  3 — Trihydroxybenzene.          1:3:  5 — Trihydroxybenzene.     1:2:  4 — Trihydroxybenzene. 

Pyrogallol  (pyrogallic  acid)  is  prepared  by  heating  gallic  acid,, 
at  about  200°  C.  (392°  F.),  until  CO2  ceases  to  be  evolved: 

C6H2(OH)3.COOH       =        C6H3(OH)3       +        CO2. 

Gallic  acid.  Pyrogallol. 

It  is  a  colorless  crystalline  substance  readily  soluble  in  water, 
and  giving  with  ferric  chlorid  a  red  color.  When  ferrous  sul- 
phate is  mixed  with  the  ferric  chlorid  it  yields  a  dark-blue  color. 
Dissolved  in  alkalis,  the  solution  turns  black  in  the  air  from 
absorption  of  oxygen.  By  shaking  this  alkaline  solution  in  a 
mixture  of  gases  of  known  volume,  the  amount  of  shrinkage 
determines  the  oxygen  present.  In  the  presence  of  light  and  the 
salts  of  gold,  silver,  and  mercury,  it  is  oxidized  to  oxalic  and  acetic 


AROMATIC    ALCOHOLS  463 

acids,  while  reducing  the  salts  to  the  metallic  state.  Like  hydro- 
quinol,  it  is  used  as  a  developer  in  photography.  It  has  been 
taken  by  mistake,  with  fatal  results.  Absorbed,  it  poisons  the  red 
corpuscles,  causing  them  to  shrink  and  lose  their  hemoglobin, 
which  changes  to  methemoglobin,  a  brownish  substance.  This 
leads  to  jaundice  and  nephritis. 

The  symptoms  are  headache,  chills,  vomiting,  cyanosis,  dark 
urine,  collapse,  tremor,  coma.  The  poison  must  be  washed  from 
the  skin  and  the  stomach.  Stimulants  and  hypodermic  injections 
of  salt  solution  are  called  for. 

Detection. — The  material  is  shaken  with  ether  to  extract  the 
pyrogallol.  This  is  then  tested  with  ferric  chlorid  and  the  silver 
salts  to  show  its  reducing  action.  Millon's  reagent  gives  a  red 
color  with  it. 

Phloroglucin,  i  :  3  :  5  — C6H3(OH)3,  is  obtained  by  fusing 
phenol  with  potash.  It  is  colorless,  crystalline,  very  soluble  in 
water,  and  sweetish  in  taste.  In  making  Gunzburg's  reagent  (p. 
549)  it  is  dissolved  in  alcohol  with  vanillin  to  detect  free  hydro- 
chloric acid.  A  test  for  pentoses  is  made  by  warming  with  a  mix- 
ture of  phloroglucinol  and  hydrochloric  acid;  a  deep  red  color 
develops. 


OXYGEN  DERIVATIVES  OF  BENZENE 

AROMATIC  ALCOHOLS 

WHEN  hydroxyl  groups  are  substituted  for  the  hydrogen  atoms 
of  the  side  chain  in  the  aromatic  hydrocarbons  higher  than  ben- 
zene, substances  are  produced  behaving  like  alcohols.  Like  the 
corresponding  fatty  alcohols,  they  are  produced  when  the  halogen 
derivatives  are  heated  writh  water  or  weak  alkalis,  or  by  reducing 
the  aldehyds.  Thus,  the  simplest  member: 

C6H5.COH       +       2H       =        C6H5.CH2.OH. 

Benzyl  aldehyd.  Benzyl  alcohol. 

Benzyl  Alcohol. — This  compound  contains  the  group:  car- 
binol,  —  CH2 .  OH,  and  C6H5,  or  phenyl,  and  is 
therefore  called  phenyl  carbinol.  It  occurs  in 
the  resins  of  styrax  and  balsams  of  Peru  and 
Tolu.  It  is  a  colorless  liquid,  which  oxidizes  first 
into  benzaldehyd  and  then  into  benzoic  acid. 


464  CYCLIC    COMPOUNDS 

AROMATIC  ALDEHYDS 

These  hold  the  same  relationship  to  alcohols  and  acids  as  that 
existing  between  their  analogues  of  the  fatty  series.  They  are  the 
alcohols  dehydrogenated. 

Benzaldehyd    (C7H6O   or   C6H5COH)  (Oil  of  Bitter  Almond}. 
— This  is  obtained  when  the  glucosid,  amygdalin, 
and  the  ferment,   emulsin   (occurring  in  bitter  al- 
monds),  are   brought   into   the   presence   of   water. 
As   these    are   present   in   the   kernels   of   cherries, 
peaches,    and   the   bark   and  leaves   of  the   cherry 
laurel,   the   same   reaction   results   when   these   are 
macerated   in    water.     The   amygdalin   is   gradually   decomposed 
into  benzaldehyd,  glucose,  and  hydrocyanic  acid: 

C20H27NOn   +   2H20   ==    2CBH12Oe   +   HCN   +    C7H6O 

Amygdalin.  Glucose.          Hydrocyanic  acid.  Benzaldehyd. 

By  distillation,  an  oil  (oleum  amygdalce  amarce)  comes  over 
which  contains  by  weight  85  per  cent,  of  benzaldehyd  and  2  to 
4  per  cent,  of  hydrocyanic  acid.  In  the  laboratory  benzaldehyd  is 
prepared  from  benzal  chlorid  with  dilute  sulphuric  acid. 

It  is  a  colorless  liquid  with  the  smell  of  almond  and  a  burning 
taste,  sparingly  soluble  in  water,  but  freely  in  alcohol.  In  the 
crude  oil  of  bitter  almonds  its  association  with  hydrocyanic  acid 
makes  it  poisonous  (p.  194). 

Vanillin.— m-Methoxy-p-oxybenzaldehyd,  C6H3.COH.(O.CH3).- 
OH,  is  the  odoriferous  principle  of  vanilla  occurring  in  colorless 
needles.  The  coniferous  plants  yield  a  glucosid,  coniferin,  which 
by  oxidation  gives  vanillin.  It  is  made  by  synthesis  from  guaiacol. 

Salicylic  Aldehyd. — Salicylal,  salicylous  acid,  0-oxybenzalde- 
hyd,  C6H4(OH)COH,  is  the  odoriferous  principle  in  the  essential 
oil  of  Spiraa  ulmaria.  It  can  be  made  by  oxidizing  salicin.  It 
is  an  aromatic  colorless  oil  having  the  properties  of  an  aldehyd 
and  a  phenol. 

AROMATIC  ACIDS 

The  acids  of  the  benzene  series  containing  carboxyl,  -COOH, 
are  derived  by  substituting  i  or  more  such  groups  for  the  same 
number  of  hydrogen  atoms.  Substitution  in  the  benzene  nucleus 
itself  yields,  beside  the  simplest  member,  benzoic  acid,  C6H5.- 
COOH,  the  3  isomeric  phthalic  acids,  dicarboxylic,  C6H4(COOH)2; 
the  3  tricarboxylic,  C6H3(COOH)3,  etc.  Toluene  and  the  higher 
members  having  methyl  side  chains  yield  2  classes  of  acids,  ac- 
cording as  the  substitution  is  in  the  nucleus  or  in  the  side  chain. 
Thus:  there  are  3  isomeric  toluic  acids,  C6H4  .  CH3 .  COOH,  of 
the  first  class,  and  phenyl  acetic  acid,  C6H5 .  CH2 .  COOH,  of  the 
second  class. 


AROMATIC    ACIDS  465 

The  only  important  aromatic  carboxylic  acid  is  benzoic.  All 
aromatic  hydrocarbons  which  contain  only  i  side  chain  yield 
benzoic  acid  when  oxidized  with  nitric  or  chromic  acid.  Thus: 

C6H5.CH3     +     30     =      C6H5.COOH     +     H2O. 

Toluene.  Benzoic  acid. 

When  the  hydrocarbons  have  2  side  chains,  phthalic  acid  is 
formed. 

The  aromatic  acids  crystallize,  are  slightly  soluble  in  water, 
and  when  heated  usually  volatilize  without  decomposing. 

Benzoic    acid,    C7H6O2,    receives   its    name    from    its    original 
source,  gum  benzoin.     It  is  also  present  in  balsam  of          COOH 
Peru.     As  the  compound  hippuric   acid  or  benzoyl- 
glycin  it  is  present  in  the  urine  of  herbivora.     From 
the  latter  combination  it  can  be  obtained  by  boiling 
with  hydrochloric  acid: 

C6H5.CO.NH.  CH2COOH     +      HC1     +     H2O      = 

Hippuric  acid. 

C6H5COOH     +     NH2 .  CH2 .  COOH,  HC1 

Benzoic  acid.  Glycin  hydrochlorid. 

It  can  be  sublimed  from  gum  benzoin,  or  be  prepared  by  oxidizing 
benzaldehyd,  benzyl  alcohol,  or  toluene. 

Properties. — It  forms  white  glistening  plates  which  sublime  at 
100°  C.  (212°  F.),  melt  at  120°  C.  (248°  F.),  boil  at  250°  C. 
(482°  F.).  Its  vapor,  derived  from  benzoin,  has  an  aromatic 
odor,  but  the  synthetic  acid  is  odorless.  Sparingly  soluble  in 
cold  water,  it  dissolves  readily  in  hot  water,  alcohol,  and  ether. 
As  a  monobasic  acid  it  forms  but  i  series  of  salts,  such  as  the 
official  benzoates  of  sodium,  lithium,  calcium,  and  ammonium. 

Test. — When  benzoic  acid  or  its  salts  are  in  neutralized  solu- 
tion they  yield  to  neutral  ferric  chlorid  a  red  or  flesh-colored 
precipitate  of  ferric  benzoate. 

Medical  Uses.— The  U.  S.  Board  of  Food  Inspection  (1911) 
regard  benzoic  acid  and  sodium  benzoate  as  harmful  when  used 
to  preserve  food.  The  practice  is  very  extensive  in  condiments, 
and  is  permitted  in  quantities  not  to  exceed  one-tenth  of  i  per 
cent.;  in  larger  amounts  it  is  condemned.  Benzoic  acid  is  an 
antiseptic  and  antipyretic.  Given  in  full  doses,  it  increases  the 
acidity  of  the  urine  by  its  conversion  in  the  body  into  hippuric  acid. 
It  is  used  to  correct  the  alkaline  urine  of  cystitis.  Dose:  5  to  20  gr. 
(0.3-1.25  gm.). 

Excretion  of  Cyclic  Compounds. — Aromatic  bodies  are  very 
stable,  owing  to  the  resistance  offered  to  oxidation  by  the  benzene 


466  CYCLIC    COMPOUNDS 

nucleus.  Once  absorbed,  the  nucleus  persists,  though  when 
eliminated  it  has  formed  a  new  combination.  In  another  place 
(p.  455)  it  has  been  stated  that  phenol  containing  the  OH  ben- 
zene ring  is  absorbed  by  the  intestines  and  passes  out  by  the 
kidneys  as  an  acid  ester,  either  as  potassium  sulphophenolate  or 
phenol  glycuronate.  So  benzoic  acid  having  a  CO  OH  benzene 
ring,  if  it  be  fed  to  an  animal,  is  excreted  as  an  amin-ester  of  glyco- 
coll,  viz.,  hippuric  acid,  and  does  not  undergo  oxidation. 

C6H5COOH     +     CH2NH2COOH     = 

Benzoic  acid.  Glycocoll. 

C6H5.  CO.NHCH2COOH     +     H2O. 

Hippuric  acid. 

The  suffix  -uric  acid  is  used  to  denote  a  glycocoll  amin-ester; 
thus,  salicylic  acid  escapes  from  the  body  as  salicyluric  acid. 
This  termination  merely  means  that  it  is  an  acid  in  the  urine,  not 
that  it  is  akin  to  uric  acid. 

Benzoyl  chlorid,  C6H5COC1,  is  prepared  by  the  action  of 
hydrochloric  acid  on  benzoic  acid: 

C6H5COOH     +      HC1     =      C6H5COC1     +     H2O. 

Its  chlorin  atom  is  readily  replaced  by  an  alcoholic  group  to  form 
an  ester  or  by  an  amino-(NH2)  group  to  form  an  amin-ester  of 
benzoyl,  C6H5 .  CO.  Thus  in  an  alkaline  solution: 

C6H5COC1     +     HOC2H5     =     C6H5COOC2H5     +     HC1. 

Ethyl  alcohol.  Benzoyl  ethyl  ester. 

The  alcohol  has  been  benzoylized.  When  the  monosaccharids  are 
thus  treated  they  make  crystallizable  products,  proving  the  presence 
of  an  alcoholic  or  hydroxyl  group  in  their  constitution. 

Phthalic  Acid  (C6H4(COOH)2).—  The  simplest  and  most  im- 
portant dicarboxylic  acids  are  the  3  whose  structure  is  represented 
below.  They  may  be  prepared  by  oxidizing  the  corresponding 
dimethylbenzenes  with  nitric  acid. 

COOH  COOH  COOH 

I       I 

H 

COOH 

Orthophthalic  acid.  Isophthalic  acid.  Terephthalic  acid. 

When  strongly  heated  orthophthalic  acid  is  converted  to  phthalic 

CO 
anhydrid,   C6H4<CO>O.      When  this  last  compound  is  heated 


HYDROXY-  OR  PHENOL  ACIDS  467 

with  phenol  and  zinc  chlorid  the  product  is  phenolphthalein, 
C20H14O4,  water  being  eliminated.  This  occurs  in  yellowish 
crystals,  which  when  dissolved,  i  per  cent.,  in  alcohol  make  a 
valuable  indicator  in  alkalimetry.  Added  to  alkaline  solutions  it 
forms  a  salt  which  imparts  a  deep-pink  color,  destroyed,  however, 
by  the  addition  of  acids  (p.  126).  It  is  a  complex  derivative 
of  phthalic  acid  containing  three  benzene  rings.  It  is  given  as  a 
painless  cathartic.  Dose:  1-5  gr.  (0.06-0.30  gm.).  "Phthalins" 
are  a  different  group  of  little  importance. 

HYDROXY-  OR  PHENOL  ACIDS 

These  are  derived  from  benzoic  acid  and  its  homologues  as 
glycollic  acid  is  from  acetic  acid — that  is,  by  substitution  of  hy- 
droxyl  for  hydrogen.  When  that  group  is  united  to  the  carbon 
of  the  nucleus,  the  compound  has  something  of  the  character 
of  phenols.  Thus,  the  3  isomeric  hydroxybenzoic  acids,  C6H4(OH). 
COOH,  are  not  only  carboxylic  acids  (having  —  COOH),  but 
are  also  phenols  (having  —OH).  This  class  includes  the  im- 
portant acids — salicylic,  gallic,  and  tannic. 

They  may  be  obtained  indirectly  from  benzoic  acid  or  its 
homologues  by  the  same  reactions  given  for  the  preparation  of 
phenol  from  benzene — that  is,  first,  a  nitro-compound;  second, 
reduction  to  an  amido-compound;  and,  finally,  treatment  with 
nitrous  acid. 

Another  synthetic  method  is  to  prepare  the  aldehyd  by  the 
action  of  chloroform  on  the  corresponding  phenol  in  the  presence 
of  caustic  soda.  Exposure  to  the  air  oxidizes  the  aldehyd  into  the 
acid. 

The  hydroxy  acids  are  colorless,  crystalline,  and  soluble  in 
water.  They  form  salts  when  treated  with  metallic  carbonates 
or  hydroxids;  the  hydrogen  of  the  carboxyl,  —COOH,  is  dis- 
placed, and,  with  excess  of  alkali,  that  of  the  hydroxyl  also. 

Salicylic  acid  (C6H4(OH)  .  COOH)  (o-hydroxybenzoic  acid) 
occurs  in  considerable  amount  in  oil  of  winter- 

/"\TT 

green  (gaultheria)  as  methyl  salicylate.  It  may 
also  be  obtained  by  oxidizing  salicyl  alcohol  or 
salicyl  aldehyd. 

Salicylic  acid  is  prepared  on  a  commercial 
scale  as  follows:  Carbolic  acid  is  treated  with 
caustic  soda,  forming  sodium  phenolate.  This  is  saturated  with 
carbon  dioxid  under  pressure,  and  heated  at  200°  C.  (392°  F.)  to 
form  sodium  phenyl  carbonate: 

C6H5 .  ONa     +      CO2     =      C6H5.  O.  COONa 

Sodium  phenolate.  Sodium  phenyl  carbonate. 


468  CYCLIC    COMPOUNDS 

By  heating  this  product  in  the  vapor  of  carbon  dioxid  under 
pressure  there  is  a  migration  of  atoms  in  the  molecule,  with  com- 
plete transformation  to  sodium  salicylate: 

C6H5 .  O  .  COONa  C6H4 .  OH  .  COONa 

Sodium  phenyl  carbonate.  Sodium  salicylate. 

Properties. — Salicylic  acid  is  a  white,  crystalline  solid,  odorless, 
sweetish,  and  acrid  in  taste,  sparingly  soluble  in  cold,  but  readily 
in  hot  water,  alcohol,  or  ether.  It  sublimes  at  200°  C.  (392°  F.). 
The  monometallic  salts,  such  as  sodium  salicylate,  are  soluble; 
the  dibasic  dimetallic  salts,  such  as  C6H4(ONa)  .  COONa,  are 
decomposed  by  carbonic  acid  with  the  formation  of  the  mono- 
metallic salt  and  a  carbonate.  With  neutral  ferric  chlorid  it  gives 
an  intense  violet  color. 

Salicylic  acid  is  a  valuable  antiseptic  and  antirheumatic,  pref- 
erable to  carbolic  acid  as  a  disinfectant  because  it  is  odorless. 

It  is  often  added  to  liquors  and  foods  as  a  preservative.  Dose: 
10  to  15  gr.  (0.6-1  gm.)  every  two  hours  or  less. 

Toxicology. — Salicylic  acid  figures  as  a  poison  from  accidental 
overdosing  and  from  its  widespread  use  in  preserving  food  and 
drink.  In  the  body  it  becomes  conjugate  with  glycocoll  and  is 
eliminated  partly  as  salicyluric  acid  and  partly  unaltered. 

Symptoms. — These  are  pain  and  irritation  of  the  pharynx  and 
stomach,  difficulty  in  swallowing,  vomiting,  diarrhea.  The  face 
is  flushed  and  the  head  feels  full,  with  roaring  in  the  ears.  Vision 
becomes  dim  and  the  mind  confused,  delirious,  and,  later,  com- 
atose. The  urine  may  be  albuminous  and  discolored  by  hematin. 
The  pulse  is  weak  and  breathing  labored.  When  minute  quan- 
tities are  taken  daily  in  food  the  appetite  suffers,  digestion  is  im- 
paired, diarrhea  alternates  with  constipation,  eczema  appears,  the 
mind  is  depressed,  and  the  urine  may  be  albuminous. 

Fatal  Dose. — One  ounce  (31  gm.)  has  proved  fatal  after  four 
days.  A  less  quantity  would  probably  be  fatal  were  the  heart  or 
kidneys  diseased. 

Treatment. — Evacuation  and  washing  out  of  the  stomach  should 
be  followed  by  the  free  use  of  rawr  eggs  and  milk. 

Tests. — Beside  the  tests  given  for  phenol  (p.  457)  with  bromin 
water,  ferric  chlorid,  and  Millon's  reagent,  a  more  characteristic 
one  is  used.  The  material  is  put  in  a  test-tube  with  methyl  alco- 
hol and  one-half  as  much  sulphuric  acid.  Warmed,  cooled,  and 
warmed  again,  the  odor  of  oil  of  wintergreen  is  noted. 

To  detect  salicylic  acid  in  beer,  wine,  milk,  and  food:  acidify 
100  c.c.  with  dilute  sulphuric  acid  and  then  extract  with  equal 
parts  of  benzine  and  ether.  Evaporate  the  extract  after  separa- 


HYDROXY-  OR  PHENOL  ACIDS  469 

tion,  and  test  the  residue  with  ferric  chlorid;  a  violet  color  is  pro- 
duced. 

Acetyl-salicylic  acid,  C6H4 .  COOH(C2H3O2)  (aspirin)  occurs 
in  white  needles,  soluble  in  100  parts  of  water,  but  freely  in  alcohol 
and  ether.  It  is  used  like  sodium  salicylate  for  rheumatism  in 
doses  of  5  to  20  gr.  (0.32-20  gm.).  Salicylic  acid  is  set  free  in  the 
intestines.  It  is  decomposed  by  heat,  moisture,  or  alkalies. 

Methyl     salicylate    (C6H4(OH)  .  COOCH3)          QH 
(artificial  oil  oj  winter  green)  is  an  ester  prepared        /\ 
by  distilling  a  mixture  of  salicylic  acid  in  methyl     /     \COO.CH3 
alcohol  and  sulphuric  acid.     It   has  the  agree- 
able odor  and  chemical  and  antirheumatic  prop-     \./ 
erties  of  the  natural  oil  obtained  from  plants. 

Phenyl  salicylate  (C6H4(OH) .  COOC6H5)  (salol)  is  an  ester 
obtained   by   heating   salicylic   acid   to    220°    C. 
(428°  F.);  or  by  dehydrating  a  mixture  of  phenol       /^ 
and   salicylic   acid.     It   is   a   white,    faintly   aro-  f      \COO.C6H6 
matic,     crystalline     powder.     Almost     insoluble  I 
in  water,  it  dissolves  readily  in  ether,  chloroform,   \v/ 
alcohol,  and  fatty  oils.     Passing  undecomposed 
through  the  stomach,  the  intestines  break  it  up  into  phenol  and 
salicylic  acid. 

It  is  antirheumatic,  antipyretic,  and  an  intestinal  antiseptic. 
Dose:  5  to  10  gr.  (0.3-0.6  gm.). 

Overdoses  cause  a  blending  of  the  poisonous  symptoms  of  sali- 
cylic acid  and  phenol.  In  the  urine  will  be  found  both  of  these 
agents,  detected  by  the  tests  given  elsewhere. 

It  is  incompatible  with  ferric  chlorid,  chloral,  camphor,  bromin 
water,  and  carbolic  acid. 

Salophen  (C6H4OHCOO)  .  C6H4NH(C2H3O)  (acetparamido- 
salol). — This  is  the  salicylic  ester  of  i,  4-acetamidophenol  derived 
from  salol,  but  with  acetyl  and  amino  groups. 

It  contains  51  per  cent,  of  salicylic  acid,  is  a  white,  tasteless, 
odorless  powder,  insoluble  in  water,  but  soluble  in  alcohol  and  ether. 
Its  action  is  antirheumatic,  antipyretic,  and  analgesic  in  doses  of 
10  gr.  (0.6  gm.).  Passing  the  stomach  unchanged,  it  breaks  up 
in  the  intestine,  liberating  salicylic  acid  and  acetylparamido- 
phenol,  which  is  not  toxic  like  the  phenol  set  free  from  salol. 
Hence  its  action  is  akin  to  that  of  a  mixture  of  salicylic  acid  and 
phenacetin. 

Salipyrin  (antipyrin  salicylate)  is  a  white,  crystalline  powder 
without  odor,  but  with  a  sweetish  taste.  It  is  sparingly  soluble 
in  water,  alcohol,  and  ether.  It  is  prepared  by  direct  union  of 
salicylic  acid  and  antipyrin,  and  is  an  antirheumatic  and  analgesic. 

Dose:   15  gr.  (i  gm.). 


470  CYCLIC    COMPOUNDS 

Salicylsulphonic  acid,  C6H3(OH).SO3H.  COOH,  is  a  crys- 
talline substance  used  in  testing  for  albumose  in  urine  (p.  615).  It 
does  not  precipitate  urates  or  resins,  but  throws  out  all  proteins. 
None  of  the  proteins  precipitated  redissolves  on  heating  except 
albumose. 

Gallic  acid  (C6H2(OH)3COOH)  (trihydroxy-benzoic  acid)  is 
found  in  tea,  nutgalls,  and  other  astringent  vegetable  products. 
It  is  prepared  by  boiling  tannic  acid  with  dilute  acids,  so  as  to 
hydrolyze  it: 

C14H1009         +         H20  2C7H605 

Tannic  acid.  Gallic  acid. 

It  is  a  white,  crystalline  solid,  melting  at  215°  C.  (419°  F.)  to 
form  pyrogallic  acid  and  carbon  dioxid.  It  is  soluble  in  water, 
imparting  an  acid  reaction  and  an  astringent  taste.  It  is  a  reduc- 
ing agent,  precipitating  metallic  gold,  silver,  and  platinum  from 
solutions  of  their  salts.  With  ferric  chlorid  it  gives  a  bluish- 
black  precipitate.  A  deep  rose  color  develops  when  its  solution 
is  treated  with  a  piece  of  potassium  cyanid. 

Dose:  5  to  20  gr.  (0.3-1.25  gm.).  It  is  incompatible  with 
ammonia,  lead  acetate,  opium,  silver  salts,  ferric  salts,  potassium 
chlorate,  and  permanganate. 

Tannic  acid  (C14H10O9=  (C6H2)2 .  (OH)5O  .  CO  .  COOH)  (tan- 
nin, digallic  acid)  occurs  in  tea  leaves,  in  the  bark  of  trees,  and 
in  large  amounts  in  nutgalls,  from  which  it  is  obtained  by  extrac- 
tion with  boiling  water,  alcohol,  or  ether.  It  is  usually  prepared 
in  light-yellow,  amorphous  scales  which  have  a  very  astringent 
taste  and  characteristic  odor.  It  is  easily  soluble  in  water,  giving 
an  acid  reaction,  and  with  ferric  chlorid  a  blue-black  or  dark-green 
color.  The  fact  that  hydrolysis  converts  it  completely  into  gallic 
acid  shows  that  it  is  an  anhydrid  of  that  acid. 

Tanning  is  the  art  of  making  leather  from  prepared  animal 
skins  or  membrane  by  immersion  in  a  solution  of  tannic  acid  or 
a  mixture  of  astringent  bark.  The  animal  substance  absorbs  and 
combines  with  the  tannin,  changing  to  leather,  which  is  tougher  and 
does  not  putrefy. 

In  medicine  tannic  acid  is  valued  as  an  astringent  and  styptic. 
Dose:  2  to  10  gr.  (0.13-0.6  gm.).  It  is  present  in  the  prepara- 
tions: glycerite  (20  per  cent.);  styptic  collodion  (20  per  cent.); 
ointment  (20  per  cent.);  troches  (i  gr.  each). 

Its  incompatibles  are  the  salts  of  iron,  lead,  mercury,  antimony, 
copper,  and  silver;  alkaloids,  gelatin,  albumin,  starch,  iodin, 
iodoform,  lime  water,  spirits  nitrous  ether,  chlorates,  and  per- 
manganates. 


POLYNUCLEATED  COMPOUNDS  471 

Tests. — Ferric  chlorid  gives  a  deep  blue  precipitate  which 
redissolves  in  excess,  changing  to  a  green  color.  Potassium 
hydroxid  yields  with  it  a  brown  color.  A  weak  solution  of  tannic 
acid,  treated  gradually  with  lime-water,  precipitates  white,  chang- 
ing to  blue  and  green. 


POLYNUCLEATED  COMPOUNDS 

THE  compounds  hitherto  studied  have  but  one  benzene  nucleus 
or  closed  chain  of  6  carbon  atoms.  They  may  be  regarded  as 
simple  derivatives  of  benzene,  being  easily  prepared  from  it  and 
reconverted  to  it.  There  are  others,  however,  which  are  also 
derivatives  of  benzene,  but  which  are  in  a  class  of  aromatic  hydro- 
carbons containing  two  independent  closed  chains  joined  at  one 
point,  like  diphenyl,  or  even  three,  like  triphenyl-methane. 


DiphenyL 

In  the  fatty  series  ethane,  C2H0,  is  sometimes  considered  as- 
having  2  methyl  groups,  CH3 .  CH3,  and  called  dimethyl.  So  it 
is  that  phenyl,  C6H5,  uniting  directly  with  another  phenyl  group,, 
forms  the  hydrocarbon  diphenyl,  C6H5— C6H5,  which  is  not,  how- 
ever, a  homologue  of  benzene.  This  and  other  hydrocarbons,, 
such  as  naphthalene  and  anthracene,  form  the  starting-points  of 
new  homologous  series,  and  become  the  parents  of  a  large  number 
of  derivatives. 

Diphenyl,  CCH5  — C6H5,  is  prepared  by  removing  with  sodium 
the  bromin  of  brombenzene  in  ethereal  solution: 

2C6H5Br    +    2Na    =    C6H5 .  C6H5    +    2NaBr. 

It  is  a  colorless  crystalline  substance,  which  when  oxidized 
forms  benzoic  acid  with  destruction  of  i  benzene  nucleus.  It 
forms  a  whole  class  of  substitution  derivatives,  of  which  one  is 
diphenylamin.  This,  dissolved  in  strong  sulphuric  acid,  is  a  deli- 
cate test  for  nitric  acid,  turning  blue  with  a  trace  of  acid  or  nitrate. 

Naphthalene,  C10H8  (naphthalin),  is  second  only  to  benzene 
in  its  economic  importance.  Like  anthracene,  it  is  the  point  from 
which  dyemakers  start  in  the  production  of  a  large  number  of 


472 


CYCLIC    COMPOUNDS 


valuable  colors.  It  is  more  abundant  in  coal-tar  than  any  other 
hydrocarbon.  Its  crude  crystals  are  deposited  on  cooling  the 
fractional  distillate  of  coal-tar,  boiling  between  180°  and  220°  C. 
(356°  and  428°  F.).  The  impurities  are  made  non-volatile  by 
the  addition  of  sulphuric  acid,  the  pure  volatile  naphthalene  being 
then  separated  by  sublimation. 

It  forms  in  large,  colorless,  lustrous  plates,  melting  at  80°  C. 
(176°  F.)  and  boiling  at  218°  C.  (424°  F.).  It  is  extremely  vola- 
tile at  all  temperatures,  giving  off  a  penetrating,  peculiar,  but  not 
ill-smelling  vapor.  This  vapor  mixed  with  coal-gas  gives  increased 
illuminating  power.  Almost  insoluble  in  water,  it  dissolves  easily 
in  hot  alcohol  and  ether.  It  is  largely  used  under  the  names  of 
moth  balls,  white  tar,  and  mineral  camphor,  to  prevent  the  destruc- 
tion of  wool  and  fur  clothing  by  moths.  Its  chief  use  is  in  making 
the  naphthalene  dyes. 

It  is  used  in  medicine  as  an  antiseptic  and  parasiticide.  Dose: 
5  to  10  gr.  (0.3-0.6  gm.). 

Toxicology. — Given  to  lower  animals,  naphthalene  causes  diar- 
rhea and  wasting,  with  cataract  and  other  changes  in  the  eye. 

Symptoms. — Poisonous  doses  are  followed  by  distress  of  the 
stomach,  vomiting,  colic,  and  purging.  Eliminated  by  the  kid- 
neys, it  causes  pain  in  the  back  and  over  the  bladder,  with  albu- 
minous and  dark-colored  urine. 

Tests. — Naphthalene  is  dissolved  out  of  a  distillate  by  means 
of  ether.  Picric  acid  yields  with  it  yellow  crystals.  A  fragment 
dissolves  in  chloral  without  change  of  color,  after  warming  on  a 
water-bath.  On  adding  to  this  a  few  drops  of  hydrochloric  acid 
and  warming,  the  mixture  turns  to  a  rose  color,  changing  to  violet 
or  brown  on  the  addition  of  zinc. 

Constitutional  Formula. — All  the  experiments  to  ascertain 
the  structure  of  the  naphthalene  molecule,  C10H8,  point  to  the  con- 
clusion that  it  and  its  derivatives  are  best  explained  when  its 
constitution  is  expressed  by  two  closed  chains  of  6  carbon  atoms, 
so  condensed  that  they  have  2  carbon  atoms  in  common,  as  shown 
by  the  double  hexagon  below: 


or  simply 


CH 

Naphthalene.  Ci0H«.  Alpha  and  beta  positions. 

To  account  for  2  isomeric  monosubstitution  products  of  naph- 
thalene, use  is  made  of  the  fact  that  the  8  hydrogen  atoms  have 
not  all  the  same  relations  to  the  rest  of  the  molecule.  For  ex- 


NAPHTHOL  473 

ample,  the  four  a  positions  are  identical,  so  are  the  four  p  posi- 
tions; but  the  one  set  differs  relatively  from  the  other.  This 
accords  with  the  fact  that  there  are  2  monochlornaphthalenes, 
2  monohydroxynaphthalenes,  etc.  At  any  angle  marked  a  the 
substituting  atom  is  in  union  with  a  carbon  atom  common  to 
both  hexagons,  while  those  marked  /5  are  not  so  placed. 

Naphthol     (C10H7OH). — The    two     monohydroxy-substitution 
derivatives  of  naphthalene  are  known  as  alpha-na,phtho\  and  beta- 
naphthol.     Their  constitution  is  shown  by  the  duplicated  rings: 
OH 


H 


a-Naphthol.  /5-NaphthoI. 

These  correspond  with  monohydric  phenols  and  are  of  great 
importance  in  dye-making.  They  are  both  derived  from  coal-tar 
or  naphthalene,  and  have  color  reactions  with  ferric  chlorid  and 
behave  in  other  ways  like  the  phenols.  Both  are  colorless  and 
crystalline,  with  a  faint  odor  recalling  that  of  carbolic  acid,  and  a 
burning  and  acrid  taste.  Beta-naphthol  is  readily  soluble  in  hot 
water,  which  is  not  the  case  with  alpha-naphthol.  Betanaph- 
tholum,  U.  S.  P.,  is  an  intestinal  antiseptic  and  parasiticide.  Dose: 
5  to  10  gr.  (0.3-0.6  gm.). 

The  hydrogen  of  the  hydroxyl  may  be  replaced  by  metals, 
giving  rise  to  a  class  of  naphtholates,  such  as  that  of  bismuth  and 
that  of  sodium,  C10H7ONa  (microcidin}. 

Experiment. — Molisch's  Test  for  Sugars. — If  a  carbohydrate 
in  solution  be  treated  with  an  alcoholic  solution  of  a-naphthol  and 
a  few  drops  of  sulphuric  acid  added  carefully  to  form  a  bottom 
layer,  a  violet  band  due  to  furfurol  appears  at  the  line  of  contact. 
This  reaction  reveals  sugar  even  when  in  combination  with  proteins, 
as  in  glucosamin. 

Toxicology. — At  one  time  beta-naphthol  was  used  as  an  alco- 
holic solution  or  ointment,  applied  to  the  skin  to  cure  scabies. 
After  such  applications  there  have  been  in  some  cases  eczema, 
retinal  changes,  acute  nephritis,  and  death.  One  dram  (3-4  gm.) 
in  the  form  of  ointment  was  fatal  to  a  pregnant  woman  in  twenty- 
five  hours. 

Treatment. — The  symptoms  call  for  the  same  procedures  as 
are  used  for  phenol-poisoning  (p.  456). 

Detection. — The  suspected  material  is  shaken  with  alcohol  and 
the  extract  evaporated  to  a  residue.  This,  warmed  with  potassium 
hydroxid  and  chloroform,  yields  a  blue  color. 

Aluminium   naphthol-disulphonate    (alumnol)    is   a   salt    of   the 


474  CYCLIC    COMPOUNDS 

dibasic  acid,  C10H3(OH)(SO3H)2,  derived  from  naphthol  by  the 
action  of  sulphuric  acid.  Naphthosalol  is  salicylate  of  ^-naphthol 
or  betol. 

Anthracene  (C14H10).—  As  the  starting-point  in  the  synthesis 
of  alizarin  (artificial  madder)  and  turkey-red  dye,  anthracene  is 
prepared  extensively  from  the  green  oil  of  coal-tar.  It  crystal- 
lizes in  colorless,  lustrous,  fluorescent  plates,  soluble  in  hot  ben- 
zene. 

Constitutional  Formula.  —  There  is  evidence  that  the  molecule 
of  anthracene  is  composed  of  condensed  nuclei,  and  experience 
shows  that  the  facts  can  be  accounted  for  if  its  constitution  be 
regarded  as  consisting  of  2  benzene  residues  linked  by  2  CH 
groups  or  3  hexagonal  rings.  Thus: 


CH     CH      CH 


or 


HO 


!CH 


CH     CH     CH 


Phenanthrene  (C14H10).— Coal-tar  yields  this  isomer  of  an- 
thracene. It  appears  to  be  diphenyl  in  which  the  2  benzene 
residues  are  united  at  the  ortho-positions  by  the  group  —  HC:CH  — 
thus:  H4C6-HC:CH-C6H4.  It  is  formed  as  a  condensation  product 
after  the  vapor  of  benzene  compounds  has  passed  through  a  red- 
hot  tube.  It  is  found  as  a  nucleus  in  the  alkaloids  morphin  and 
codein. 

CO 
Anthraquinon    (C6H4<pQ>C6H4)    (Diphenylene-diketone).— 

When  anthracene  is  treated  with  nitric  acid  it  does  not  yield  a 
nitro-derivative:  it  is  oxidized  to  anthraquinon,  C14H8O2,  2  atoms 
of  hydrogen  being  displaced  by  2  atoms  of  oxygen. 

It  crystallizes  in  yellow  needles,  and  when  acted  on  by 
sulphuric  acid  and  then  by  soda  and  potassium  chlorate 
yields,  by  complex  processes,  alizarin  or  dihydroxyanthraquinon, 

f  o 
C6H4<pQ>C6H2(OH)2.     This   is   the    active   color   principle   of 

the  madder  root.  It  produces  various  colored  compounds  with 
metallic  oxids;  for  example,  with  aluminium,  a  fast  red,  turkey 
red;  with  lime,  blue;  with  a  ferric  salt,  dark  purple. 

Alizarin  mono  sodium  sulphonate  is  the  yellow  reagent  used  by 
Topfer  as  an  indicator  for  uncombined  acids  of  the  gastric  juice, 
excess  of  caustic  soda  turning  the  tested  fluid  pure  violet  by  the 

CO 
formation    of   the  disodium  derivative,    C6H4<pQ>C6H2(ONa)2 

(Plate  6,  B,  B'). 


NITROBENZENE  475 

NITROGEN  DERIVATIVES  OF  BENZENE 

AN  important  class  of  compounds  results  from  the  ease  with 
which  nitro-  (NO2),  amido-  (NH2),  and  diazo-  (N2)  groups  are  sub- 
stituted for  the  hydrogen  of  the  benzene  nucleus.  The  nitration 
of  many  aromatic  compounds  is  accomplished  by  solution  in  nitric 
acid.  When  not  soluble  in  nitric  acid,  the  process  is  facilitated  by 
using  a  mixture  of  strong  nitric  and  sulphuric  acids.  As  a  rule,  a 
high  temperature  and  concentrated  acids  cause  the  substitution  of 
several  nitro-groups.  Generally  speaking,  the  nitro-compounds  are 
crystalline  and  yellowish,  insoluble  in  water,  but  soluble  in  benzene, 
ether,  and  alcohol. 

Nitrobenzene  (C6H5 .  NO2)  (Essence  oj  Mirbane).— When 
benzene  (10  c.c.)  is  slowly  treated  with  a  mixture  of  nitric  acid 
(12  c.c.)  and  sulphuric  acid  (16  c.c.),  and  the  vessel  kept  cool  by 
immersion  in  water,  the  benzene  dissolves.  When  poured  into 
water  a  yellow  oil  sinks  to  the  bottom.  This  is  nitrobenzene,  and 
the  reaction  is  as  follows: 

C6H6     +     HN03  C6H5N02     +      H2O. 

Nitrobenzene  is  insoluble  in  water,  has  a  specific  gravity  of  1.2, 
is  sweetish  in  taste,  and  has  a  strong  odor,  resembling  oil  of  bitter 
almond,  for  which  oil  it  is  often  substituted  in  flavors  and  perfumes, 
notwithstanding  its  poisonous  character.  Its  chief  use  is  in  the 
manufacture  of  anilin. 

Toxicology. — It  breaks  down  the  blood-corpuscles,  forms  meth- 
emoglobin  (Plate  4,  Fig.  i,  d),  and  paralyzes  the  nerve  centers. 
The  immediate  symptoms  may  not  be  noticeable  for  several 
hours,  when  suddenly  the  face  becomes  livid,  the  nails  bluish, 
the  pulse  feeble,  the  skin  cold;  giddiness  and  vomiting  may  lead 
quickly  to  coma,  sometimes  complicated  with  convulsions,  and 
often  ending  in  death  from  apnea.  If  death  is  not  prompt,  the 
case  may  be  complicated  by  jaundice.  The  same  symptoms, 
resembling  those  caused  by  hydrocyanic  acid,  have  been  induced 
by  inhalation  of  the  vapor  in  the  industries  using  nitrobenzene. 

Fatal  Dose  and  Period. — Death  would  probably  be  caused  by 
30  drops  to  i  dram.  Coma  usually  appears  in  four  hours,  with 
death  two  hours  later. 

Treatment. — Using  a  siphon  tube,  the  stomach  should  be  washed 
out  with  warm  water  freely.  Strychnin,  digitalis,  and  artificial  res- 
piration are  useful  to  sustain  the  heart  and  respiration.  Alcohol 
by  the  stomach  must  be  avoided,  as  it  favors  absorption. 

Postmortem  Appearances. — These  include  a  persistent  odor  of 
bitter  almond  and  oily  drops  of  the  nitrobenzene  in  the  alimentary 
tract.  The  blood  is  chocolate-colored  and  fluid. 


476  CYCLIC    COMPOUNDS 

Detection. — (i)  Nitrobenzene  is  dissolved  in  warm  alcohol  and 
reduced  to  anilin  by  adding  powdered  zinc,  followed  by  single 
drops  of  hydrochloric  acid  to  evolve  hydrogen  until  no  odor  of 
nitrobenzene  is  left.  The  solution,  diluted  and  made  alkaline,  is 
extracted  with  ether  and  the  residue  tested  for  anilin  (p.  478). 

(2)  A  few  grains  of  potassium  hydroxid  mixed  with  3  drops  of 
water  and  2  drops  of  carbolic  acid  are  boiled  in  a  dish  and  then  a 
few  drops  of  the  suspected  material  is  added.  After  boiling,  a 
red  ring  appears  at  the  edge,  the  red  changing  to  green  when 
calcium  hypochlorite  is  added. 

AROMATIC  AMIDO-COMPOUNDS  AND  AMINS 

In  another  place  (p.  494)  the  amids  and  amins  of  the  fatty 
series  are  referred  to  as  ammonia,  in  which  the  hydrogen  atoms 
have  been  displaced  by  fatty  radicals.  Analogous  compounds 
are  made  when  the  radicals  substituted  are  aromatic,  such  as 
amidobenzene,  C6H5 .  NH2,  and  benzylamin,  C6H5 .  CH2 .  NH2. 
Those  which,  like  amidobenzene,  have  the  amido-group  united 
directly  with  the  nucleus  are  called  amido-compounds;  those 
containing  that  group  in  the  side  chain,  like  benzylamin,  are 
called  aromatic  amins,  and  are  of  very  little  importance. 

Preparation  of  amido=compounds  in  general  is  performed  by 
reducing  the  nitro-compounds  with  nascent  hydrogen,  a  metal, 
or  stannous  chlorid.  Thus: 

C6H5NO2     +     6H     =      C6H5.NH2     +      2H2O. 

Nitrobenzene.  Amidobenzene. 

The  properties  of  the  amido-compounds  are  similar  to  those 
of  the  primary  amins.  The  basic  character  of  ammonia  is  dimin- 
ished by  the  substitution  of  phenyl,  C6H5  — ,  which  is  not  the  case 
with  the  fatty  amins.  Warmed  with  nitrous  acid  in  solution,  they 
yield  phenols,  as  the  fatty  amins  under  like  conditions  form  alcohols: 

C6H5 .  NH2   +   HN02   =    C6H5  .  OH   +   N2   +    H2O. 

Amidobenzene.  Nitrous  acid.  Phenol. 

Anilin    (C6H5 .  NH2)    (Amidobenzene,  Phenylamin}. — Anilin  is 
„      „        contained  in  coal-tar  in  small  quantities,  but  com- 
/^v  mercially  it  is  prepared  by  reducing  nitrobenzene 

HO|      ^,CH     witn  nascent  hydrogen. 

H  ||  I  When  pure,  it  is  a  colorless,  oily,  neutral  liquid, 

\  ^  with  a  faint,  peculiar  odor  and  a  bitter  taste.     Spar- 

CH  ingly  soluble  in  water,  it  dissolves  readily  in  alco- 

hol and  ether.  Exposed  to  light  it  darkens.  It 
acts  as  a  base,  neutralizing  acids  and  forming  salts,  such  as  anilin 
hydrochlorid,  C6H5 .  NH2HC1. 


AROMATIC    AMIDO-COMPOUNDS    AND    AMINS  477 

A  mixture  of  chloroform  and  alcoholic  potash  heated  with  one 
drop  of  anilin  gives  the  offensive  vapor  of  isobenzonitril,  C6H5 .  NC. 
By  oxidizing  agents,  such  as  arsenic  acid,  it  is  converted  into 
rosanilin,  from  which  derivatives  of  various  colors  are  easily 
produced.  This  is  the  basis  of  the  large  industry  of  dye-making. 
Rosanilin  chlorid,  C20H20N3C1,  forms  crystals  of  a  green,  metallic 
luster,  which  dissolve  in  warm  water  to  form  a  deep  red  solution 
that  dyes  fabrics  a  brilliant  magenta.  The  identity  in  color  of  the 
nitrate  and  other  salts  finds  explanation  in  the  same  colored  ion. 
If  the  ion  be  changed  by  the  introduction  of  methyl  for  hydrogen, 
the  changes  in  color  range  through  violet  to  blue,  according  to  the 
number  of  methyl  groups. 

Pyoktannin-blue  is  pentamethylrosanilin  chlorid,  violet  in  color, 
soluble,  and  used  as  an  antiseptic.  Methyl-blue  is  the  sodium 
sulphonate  of  triphenylrosanilin.  It  is  used  locally  as  a  disin- 
fectant, but  internally  is  poisonous,  having  caused  death  by  mis- 
take for  methylene-blue,  which  is  less  active. 

M ethylene-blue  (methylthionina  hydrochloridum,  U.  S.  P.),  is 
formed  by  the  action  of  hydrogen  sulphid  upon  an  oxidation  product 
of  para-amido-dimethylanilin.  It  occurs  in  dark  green,  bronze-like 
crystals  which  readily  make  a  deep  blue  aqueous  solution.  It  is 
used  in  dyeing,  staining  bacteriologic  specimens,  and  internally 
is  given  for  its  analgesic  and  antipyretic  effects.  Dose:  i  to  3  gr. 
(0.065-0.2  gm.). 

Toxicology. — Anilin  poisoning  is  found  in  dye-workers  who 
inhale  the  vapors,  but  others  wearing  socks  and  boots  dyed  with 
anilin  colors  have  suffered  from  absorption  by  the  skin.  Like 
nitrobenzene,  it  breaks  down  the  blood  and  paralyzes  the  nerve 
centers.  The  methemoglobin  in  the  blood  imparts  a  bluish  color 
to  the  face  and  finger-nails.  The  gait  is  unsteady,  the  head  aches 
and  is  dizzy,  the  pulse  feeble,  and  drowsiness  ends  in  coma. 
Chronic  poisoning  causes  eczema,  anemia,  and  amblyopia.  Anilin 
is  oxidized  in  the  system  to  para-amidophenol,  C6H4 .  OH  .  NH2, 
which  is  eliminated  as  a  conjugate  sulphate.  From  this  the 
urine  takes  a  dark  color  and  reduces  Fehling's  solution  like  glucose. 
The  U.  S.  Board  of  Food  Inspection  (1911)  forbids  the  use  in 
food  of  any  coal-tar  dye  except  those  known  in  commerce  as 
amaranth  and  erythrosin  red;  orange  I;  naphthol  yellow  S;  light 
green  S.  F.,  yellowish;  and  indigo  disulphacid;  of  the  official  list- 

Fatal  Dose  and  Period. — Death  is  probable  within  twenty  hours 
after  doses  of  i  fl.  oz.  (30  c.c.). 

Treatment. — When  the  poison  has  been  inhaled,  fresh  air  and 
stimulants  are  called  for;  if  swallowed,  evacuation  of  the  stomach 
and  bowels,  followed  by  stimulants. 

Postmortem  Appearances. — There  is  an  odor  of  coal-tar  or  anilin 


478  CYCLIC   COMPOUNDS 

in  the  body,  with  a  brownish  color  of  the  blood,  due  to  methemo- 
globin  (Plate  4,  Fig.  i,  d). 

Detection. — i.  A  solution  of  free  anilin  is  turned  violet  by  a  few 
drops  of  fresh  calcium  hypochlorite.  If  this  be  pale,  a  few  drops  of 
ammonium  sulphid  develops  a  visible  rose  color,  changing  yellow. 

2.  Sulphuric  acid  with  a  trace  of  anilin  turns  slowly  blue  or 
green    when    treated    with    potassium    dichromate.     The    same 
reagents  with  strychnin  yield  a  blue,  changing  to  purple  and  red. 

3.  One  drop  of  anilin  yields  with  chloroform  and  alcoholic  potash 
the  isobenzonitril  odor  (p.  388). 

Acetanilid  (C6H.  .  NH  .  C2H3O)  (Antijebrin,  Phenyl-acetanilid}. 

— When  the   hydrogen    of    the    amido-group    in 

CNHCjH3O    anilin  is  replaced  by  acid  radicals,  the  derivative 

// %^  is  called  anilid;  for    example,    acetanilid,    form- 

||  anilid,  and  oxanilid  are  anilids  prepared  by  the 

HCX       y^CH         action    of    the    corresponding    acids.     When    the 

£u  hydrogen  atom  is  displaced  by  an  alkyl  radical, 

the   derivative   is   known   as   an   alkylanilin;    for 

example,   methylanilin,   C6H5 .  NH  .  CH3. 

Preparation. — Acetanilid  is  prepared  by  boiling  anilin  with 
glacial  acetic  acid.  Anilin  acetate  is  formed  and  slowly  changes, 
during  prolonged  boiling,  to  acetanilid  and  water.  Distillation 
purifies  the  acetanilid,  which  is  collected  and  crystallized  in  lus- 
trous white  plates  having  a  burning  taste.  It  is  odorless  and  is 
greasy  to  the  touch. 

C6H5.NH2  +  CH3.COOH  =  C6H5 .  NH  .  C2H3O  +  H2O. 

Anilin.  Acetic  acid.  Acetanilid. 

Properties. — Acetanilid  melts  at  113°  C.  (235°  F.).  It  dis- 
solves sparingly  in  cold  water,  but  freely  in  hot  water,  alcohol,  and 
ether.  When  heated  with  acids  or  alkalis  it  takes  up  water,  yield- 
ing anilin  and  acetic  acid.  Its  solutions  are  neutral  and  are 
unaltered  in  color  by  either  ferric  chlorid  or  sulphuric  acid. 

Acetanilid  is  anodyne,  antiseptic,  antipyretic,  and  antirheumatic. 
It  is  the  basis  of  many  "  headache  powders."  Pulms  acetanilidi 
compositus  contains  in  10  gr.:  acetanilid,  7  gr.;  caffein,  i  gr.;  sodium 
bicarbonate,  2  gr. 

Dose:  2  to  10  gr.  (0.13-0.6  gm.).  It  is  incompatible  with 
alkaline  bromids  or  iodids,  forming  compounds  insoluble  in 
water.  It  causes  spirits  of  nitrous  ether  to  turn  yellow  and  red. 
Rubbed  with  chloral  or  carbolic  acid  it  forms  a  soft  mass. 

Toxicology. — Many  cases  of  poisoning  are  attributable  to  the 
three  anilin  derivatives — acetanilid,  exalgin,  and  phenacetin — taken 
carelessly  as  antipyretics  and  anodynes.  The  lowered  temperature 

results  from  the  amidophenol,  C6H4<QTj2,  formed  in  the  tissues 


AROMATIC    AMIDO-COMPOUNDS    AND    AMINS  479 

by  oxidation  of  the  amidobenzene  group,  and  which  is  excreted  as  a 
sulphate.  All  of  them  cause  methemoglobin  to  appear  in  the  blood 
(Plate  4,  Fig.  i,  d),  producing  cyanosis,  muscular  weakness,  dark 
or  bloody  urine,  nephritis,  and  jaundice.  Very  large  doses  cause 
sudden  profuse  perspiration,  dizziness,  collapse,  dyspnea,  coma, 
and  convulsions.  Chronic  poisoning  from  abuse  of  "headache 
powder"  is  characterized  by  cyanosis,  dyspnea,  weakness,  dys- 
pepsia, anemia,  wasting,  and  dark-colored  urine. 

Fatal  Dose  oj  Acetanilid. — In  cases  of  weak  heart  or  typhoid 
fever  small  doses  of  10  to  30  gr.  (0.6-2  gm.)  may  cause  alarming 
symptoms.  Death  has  followed  60  gr. 

Treatment. — Besides  clearing  out  the  stomach  and  bowels,  there 
is  an  immediate  indication  for  hypodermic  doses  of  strychnin,  fol- 
lowed by  normal  salt  solution,  and  keeping  the  recumbent  position. 

Detection. — i.  Indophenol  Reaction.  A  gram  of  acetanilid  boiled 
with  2  c.c.  of  strong  hydrochloric  acid  and  cooled  is  treated  with 
2  c.c.  of  the  saturated  solution  of  phenol  and  a  few  drops  of 
calcium  hypochlorite  or  chlorin  water.  The  red  color  thus  formed 
is  altered  by  addition  of  ammonia  to  a  blue.  This  test  identifies 
the  amidophenol  in  the  urine  if  performed  by  the  following  method: 
The  urine,  concentrated  on  a  water-bath,  is  boiled  for  three  minutes 
with  one-tenth  its  volume  of  hydrochloric  acid  to  set  free  the 
amidophenol  from  sulphuric  acid.  After  cooling  it  is  shaken 
with  an  equal  volume  of  ether,  which  is  separated  and  evaporated. 
The  residue,  dissolved  in  water,  is  treated  with  a  few  drops  of 
solution  of  phenol  and  some  solution  of  chlorinated  lime.  The 
amidophenol  first  formed  gives  a  red  color  of  indophenol  with 
the  phenol  and  chlorin,  which  ammonia  changes  to  blue. 

2.  Heated  with  chloroform  and  alcoholic  potash,  the  isobenzo- 
nitril  odor  is  developed  (p.  388). 

Methylacetanilid  (C6H5 .  N  .  CH3 .  C2H3O)  (Exalgin).—^  the 
action  of  methyl  iodid  upon  sodium  acetanilid 
the  methyl  group  is  substituted  for  an  atom  of 
hydrogen  in  acetanilid.  Methylacetanilid  is  crys- 
talline, tasteless,  faintly  aromatic,  sparingly  sol- 
uble in  water,  freely  in  alcohol.  It  is  antipyretic 
and  analgesic. 

Dose:  4  to  7  gr.  (0.25-0.4  gm.). 

Phenacetin  (C6H4 .  C2H5 .  O  .  NHC2H3O)  (Acetphenetidin, 
Oxyethylacetanilid) . — The  effect  of  reducing  C.NHCHO 

agents  upon  a  nitrophenol,  C6H4 .  OH  .  NO2  is  to 
form  the  related  amidophenol,  C6H4 .  OH  .  NH2.  H 
When  ethyl  is  substituted  for  the  hydrogen  of  H 
the  — OH,  a  corresponding  ethylic  ether  or  phe- 
netidin  is  the  result,  C6H4.  O(C2H.) .  NH2.    When  C.O.C2H5 


480  CYCLIC    COMPOUNDS 

paraphenetidin  is  treated  with  glacial  acetic  acid,  the  acetyl  group, 
C2H3O — ,  is  substituted  for  i  atom  of  hydrogen  in  the  — NH2,  and 
the  product  is  acetphenetidinum  (U.  S.  P.). 

Its  composition  differs  from  that  of  acetanilid  in  having  oxy- 
ethyl,  — O  .  C2H5,  introduced  in  place  of  an  atom  of  hydrogen  in 
the  nucleus,  which  causes  a  slower  cleavage  into  amidophenol. 

It  is  extensively  used  as  an  antipyretic,  analgesic,  and  anti- 
neuralgic,  under  the  name  phenacetin.  It  is  a  white,  odorless, 
tasteless,  crystalline  powder,  sparingly  soluble  in  water,  readily  so 
in  alcohol.  Cases  of  poisoning  have  occurred  from  overdoses, 
though  it  is  a  safer  medicine  than  acetanilid.  The  symptoms  and 
treatment  are  the  same  as  those  of  acetanilid. 

1.  Nitric  Acid  Test. — With  a  few  drops  of  concentrated  nitric 
acid  phenacetin  yields  a  yellow  to  orange-red  color.     Heat  com- 
pletes the  solution,  which  on  cooling  gives  crystals  of  nitrophen- 
acetin. 

2.  Indophenol   Test. — The  same  reaction  as  that  of  acetanilid, 
given  above.     Three  per  cent,  chromic  acid  may  be  substituted  for 
the  calcium  hypochlorite. 

Dose:  5  to  15  gr.  (0.3-1  gm.).  Its  incompatibles  are  chloral, 
carbolic  acid,  iodin,  salicylic,  chromic,  and  nitric  acids. 

Methacetin  [C6H4.  OCH3 .  NH(C2H3O)]  (Oxymethacetanilid). 
— The  methyl  ether  of  an  amidophenol  is  known  as  an  anisidin, 
C6H4 .  OCH3  .  NH2.  Acted  on  by  glacial  acetic  acid,  this  forms 
methacetin  by  the  substitution  of  oxymethyl  for  an  atom  of  hydro- 
gen in  the  nucleus  and  of  acetyl  in  the  NH2. 

This  substance  crystallizes  in  white,  odorless,  and  tasteless 
lustrous  scales,  sparingly  soluble  in  water,  readily  so  in  alcohol.  It 
is  used  as  an  antipyretic  and  analgesic. 

Dose:  3  to  8  gr.  (0.2-0.5  gm.). 


DIAZO-COMPOUNDS 

When  anilin  hydrochlorid  in  very  cold  solution  is  mixed  with 
sodium  nitrite,  and  then,  by  the  addition  of  hydrochloric  acid, 
nitrous  acid  is  liberated  in  the  mixture,  a  reaction  takes  place  with 
the  formation  of  diazobenzene  chlorid: 

C6H5.NH2.HC1     +     HNO2     =      C6H5 .  N2C1     +     2HO. 

Anilin  hydrochlorid.  Diazobenzene  chlorid. 

The  term  diazo  refers  to  the  2  atoms  of  nitrogen  linking  the 
phenyl  radical  to  other  components:  R  —  N2  — .  When  the  free 
bond  is  united  to  acid  groups  or  halogens,  the  products  are  called 
diazo  salts:  C6H5 .  N2 .  SO4H  is  diazobenzene  sulphate.  They 


PLATE    3. 


PHENYLHYDRAZIN  TEST  FOR  SUGARS. 

In  a  test  tube  put  nearly  ^  in.  (I  gm.)  of  phenylhydrazin  hydrochlorid,  an  equal 
quantity  of  powdered  sodium  acetate,  and  enough  of  the  suspected  fluid  to  half-fill 
the  tube.  The  acetate  dissolves  as  the  tube  is  heated.  Boil  for  2  minutes  and 
examine  after  20  minutes,  or,  if  hurried,  examine  a  drop  under  the  microscope  at  once 
without  a  cover-glass.  In  2  or  3  minutes  the  crystals  form  :  a,  Sheaves  and  stars  of 

needles glucosazone  ;  b,  rosettes  of  lance-shaped'  crystals — maltosazone  ;  t,  spicules 

in  burr-like  clusters — lactosazone. 


DIAZO-COMPOUNDS  481 

may   be   regarded   as   compounds   of   hypothetic  N.NHSO< 

diazobenzene,  C6H5 .  N2 .  OH,  and  its  derivatives. 
These  salts,  when  dry,  are  unstable  to  the  degree 
of  being  explosive.  They  are  colorless,  crystal- 
line, and  very  soluble  in  water.  Their  value  in 
industrial  chemistry  is  very  great,  as  they  furnish 
a  mother  substance  susceptible  to  many  reactions, 
producing  a  large  class  of  dye  substances  of  varying  colors. 

When  one  bond  of  each  of  the  2  nitrogen  atoms  is  united  to  an 
atom  of  hydrogen,  a  hydrazo-compound  is  formed. 

Phenylhydrazin  (C6H5 .  HN  .  NH2).— This  important  sub- 
stance can  be  prepared  by  reducing  diazobenzene  with  hydro- 
sen: 

C .  HN .  NH, 

C6H5.N2C1     +     4H    =     C6H3 .  NH .  NH2 . HC1  /\, 

Diazobenzene  chlorid.  Phenylhydrazin  hydrochlorid.  nil  iCH 

From  the  hydrochlorid  the  free  base,  phenyl-  HC-\     .^^ 
hydrazin,    is    liberated    by    potash.      Hydrazin,  QH 

or  diamin,  is  the  name  given  to  the  group  H2N  — 
NH2,  from  which  it  is  assumed  these  reduction  products  are  derived. 

Phenylhydrazin  is  a  crystalline,  sparingly  soluble,  strong  base, 
forming  salts  with  acids.  Both  base  and  salts  reduce  Fehling's 
solution  in  the  cold.  It  reacts  with  aldehyds  and  ketones  to  form 
hydrazones,  and  with  grape-,  milk-,  and  malt-sugars  to  form  osa- 
zones.  Cane-sugar  does  not  yield  an  osazone.  As  these  sub- 
stances are  usually  crystalline  solids  of  difficult  solubility,  they 
are  often  formed  in  tests  for  identifying  and  isolating  aldehyds 
and  sugars.  The  osazones  are  separated  as  crystals  from  aque- 
ous solutions  of  sugars  by  boiling  with  excess  of  phenylhydrazin 
hydrochlorid  and  sodium  acetate  (Plate  3,  a,  b,  c). 

Phenylhydrazin  hydrochlorid  is  a  white,  changing  to  a  fawn- 
colored,  crystalline  powder,  with  an  agreeable  odor.  It  decomposes 
readily  into  a  dark,  offensive  paste,  which  is  no  longer  suitable  as  a 
reagent  for  sugar  testing.  The  crystalline  powder  should  not  be 
permitted  to  touch  the  skin,  as  it  may  cause  an  annoying  eruption. 

Another  interesting  use  of  phenylhydrazin  is  in  the  manufacture 
of  antipyrin. 

Antipyrin  (C6H5 .  (CH3)2 .  N2C3OH)  (Phenyl-dimethyl-pyrazolon, 
Phenazone). — This    is    a    synthetic    base,    a 
derivative   of   phenylhydrazin,    not   found   in 
nature,  and  hence  sometimes  called  an  arti- 
ficial  alkaloid.     It    is    prepared    by    treating 
diacetic  ether  with  phenylhydrazin,   making 
phenyl-methyl-pyrazolon;     and     then     intro- 
ducing a  second  methyl  group  by  heating  with   methyl  iodid. 
31 


482  CYCLIC    COMPOUNDS 

t  It  is  a  white,  odorless,  bitter,  crystalline  powder,  readily  soluble 
in  water  and  alcohol.  It  fuses  at  113°  C.  (235  °  F.)  and  is  strongly 
basic,  forming  soluble  salts.  With  ferric  chlorid  it  yields  a  deep 
red  color,  and  with  nitrous  acid  a  bluish  green  color. 

In  medicine  it  is  used  locally  as  a  styptic  and  internally  as  an  anti- 
pyretic, antirheumatic,  and  analgesic.  Dose:  5  to  15  gr.  (0.3-1 
gm.).  It  has  many  incompatibles:  the  halogens,  ammonia  water, 
sodium  bicarbonate  and  salicylate,  chloral,  copper  sulphate, 
chromic  acid,  iodids,  lead  subacetate,  calomel,  mercuric  chlorid, 
alum,  carbolic  acid,  amyl  nitrite,  benzoates,  beta-naphthol,  spirits  of 
nitrous  ether,  quinin,  ferric  chlorid,  tartar  emetic,  tannic  acid,  and 
vegetable  astringents. 

Toxicology.  —  Poisoning  from  antipyrin  is  nearly  always  due  to 
the  free  use  of  it  as  a  medicine  in  cases  many  of  which  were  unfit 
for  it  because  of  defective  heart  or  kidneys. 

Acute  cases  show  feeble  pulse,  difficult  breathing,  and  cyanosis, 
not  so  great  as  that  caused  by  acetanilid.  Muscular  tremblings 
may  be  associated  with  the  stupor,  collapse,  and  coma. 

Chronic  poisoning  from  habitual  use  causes  edema  of  the  face, 
cutaneous  affections,  indigestion,  mental  dulness,  and  anemia. 

Fatal  Dose.  —  In  patients  having  heart  or  lung  diseases  20  gr. 
would  be  dangerous. 

Treatment.  —  The  patient  is  placed  in  the  supine  position  and  air 
or  oxygen  is  supplied  freely.  The  stomach  is  evacuated  by  emetics 
or  the  siphon  tube.  Ammonia  may  be  inhaled  and  hypodermic 
injections  given  of  whisky  or  strychnin. 

Tests.  —  i.  Nitrous  acid  liberated  from  a  solution  of  potassium 
nitrite  by  sulphuric  acid  causes  with  an  aqueous  solution  of  anti- 
pyrin a  blue-green  nitroso-antipyrin. 

2.  Ferric  chlorid  gives  a  red  color  with  antipyrin,  like  that  pro- 
duced with  diacetic  acid  (Plate  8,  Fig.  6).     The  color  disappears 
by  the  action  of  mineral  acids. 

3.  Fuming  nitric  acid,  two  drops,  added  to  a  few  drops  of  solution 
of  antipyrin,  gives  a  green   color.     After   heating  this  to   boiling 
another  drop  of  the  acid  produces  a  red  color. 

Saccharin  (C6H4CO  .  SO2NH)  (Benzosulphinidum,  Benzoylsul- 
phonic  Imid).  —  In  making  this  substance  0-sulphobenzoic  acid  is 
first  prepared,  and  this,  treated  with  ammonia,  yields  the  imid: 

+    2H20. 


Sulphobenzoic  acid.  Saccharin. 


It  is  a  white^powder  with  a  slight  aromatic  odor  and  a  remarkably 
sweet  taste,  being  nearly  300  times  as  sweet  as  cane-sugar.  It  is 
sparingly  soluble  in  water,  but  freely  so  in  ether  and  alcohol.  Its 


PYRIDIN    AND    ITS    DERIVATIVES  483 

solubility  is  increased  by  alkaline  carbonates,  which  convert  it  to 
soluble  saccharin. 

Experiment. — Its  presence  is  detected  by  acidulating  with  sul- 
phuric acid  the  sugar  or  other  suspected  substance  and  shaking 
with  ether,  which  does  not  dissolve  sugar,  but  extracts  the  saccharin. 
On  separation  and  evaporation  the  residue  of  saccharin  is  crys- 
talline and  sweet. 

Uses. — It  is  used  to  disguise  the  taste  of  unpalatable  medicines, 
and  as  a  substitute  for  sugar  in  diabetes,  obesity,  and  gout. 

Toxicology. — It  retards  the  action  of  the  enzyms  in  the  digestive 
fluids  and  also  those  of  the  blood  and  tissues.  To  a  certain  extent 
it  depresses  general  metabolism. 

Benzidin  (NH2 .  C6H4 .  C6H4 .  NH2)  (p-Diamidodiphenyl).—This 
may  be  compared  with  two  molecules  of  anilin.  It  is  made  by 
the  action  of  acids,  causing  an  intramolecular  rearrangement  in 
hydrazobenzene,  C6H5 .  NH  .  NH  .  C6H5.  It  occurs  in  colorless, 
shining  plates,  is  strongly  basic,  and  is  used  in  the  preparation 
of  azo-dyes  such  as  congo-red,  whose  sodium  salt  is  a  scarlet 
powder  which  is  turned  blue  by  acids.  Benzidin  is  used  in  a 
delicate  test  for  blood  (p.  617). 


HETEROCYCLIC  COMPOUNDS 

THE  cyclic  compounds  previously  described  have  6  carbon  atoms 
in  the  ring.  As  the  atoms  at  the  angles  are  alike,  they  are  called 
isocyclic.  If  a  ring  contains  fewer  than  6  carbon  atoms,  it  is 
irregular  and  the  compound  is  called  heterocyclic.  One  of  the  C 
atoms  may  be  replaced  by  N,  as  in  pyridin,  or  the  ring  may  have 
only  4  C  atoms  with  NH,  as  in  pyrrole. 

CH  CH 


'\^  \<r 

CH  N 

Pyrrole. 

PYRIDIN  AND  ITS  DERIVATIVES 

Among  the  constituents  of  coal-tar  have  been  found  certain 
aromatic  bases  allied  to  the  alkaloids  and  known  as  pyridin  bases. 
They  were  first  discovered  in  bone  oil,  a  dark  brown  liquid  of  dis- 
agreeable odor,  formed  when  bones  are  heated  in  the  preparation  of 


484  CYCLIC    COMPOUNDS 

boneblack.     Purified  by  distillation,  this  bone  oil  was  at  one  time 
used  in  medicine  under  the  name  of  DippeVs  oil. 

Pyridin,  C5H5N,  is  a  product  of  destructive  distillation  of  many 
nitrogenous  organic  substances,  and  hence  found  in  tobacco  smoke. 
It  is  prepared  by  first  making  nicotinic  acid,  C6H5NO2,  by  oxid- 
izing nicotin.  This,  when  distilled  with  lime,  yields  pyridin,  as 
benzoic  acid  by  the  same  process  gives  benzene: 

C5H4N.COOH     =      C5H5N     +      CO2. 

Nicotinic  acid.  Pyridin. 

Many  considerations  have  established  the  opinion  that  pyridin, 
like  benzene,  has  a  closed  chain  or  nucleus  with  trivalent  nitrogen 
substituted  for  the  trivalent  group,  CH=.  Its  constitution  is  repre- 
sented in  the  formula  given  above. 

Pyridin  is  a  colorless  liquid  with  a  pungent,  empyreumatic  odor 
and  sharp  taste,  freely  miscible  with  water,  alcohol,  ether,  and  oils. 
Its  specific  gravity  is  1.003,  and  its  boiling-point  1 16°  C.  (241°  F.  ). 
It  is  a  very  stable  substance  of  strongly  basic  properties,  alkaline  in 
reaction.  It  has  been  used  in  medicine  as  a  respiratory  sedative. 
Dose:  2  to  10  drops. 

Piperidein  (C5H8NH). — By  the  action  of  nascent  hydrogen  on 
the  pyridins  the  several  carbon  atoms  take  up  additional  hydrogen 
atoms,  forming  hydropyridins.  The  best  known  tetra-hydropyridin 
is  the  compound  piperidein,  of  which  the  betel  alkaloids  are  deriva- 
tives. 

Piperidin  (C5H10NH)  (Hexahydropyridin). — When  pyridin  is 
dissolved  in  alcohol  and  treated  with  sodium,  piperidin  is  formed  as 
a  reduction  product: 

C5H5N       +       6H  C5H10NH 

Pyridin.  Piperidin. 

It  is  reconverted  to  pyridin  on  oxidation  with  sulphuric  acid. 

It  has  been  shown  that  the  constitution  of  piperidin  is  repre- 
sented by  the  formula: 

CH, 


NH 

Piperidin. 


The  alkaloid  piperin,  found  in  pepper,  yields  piperidin  when 
decomposed  by  boiling  alkalis.  Piperidin  is  a  colorless  liquid  with 
an  odor  of  pepper.  It  is  miscible  with  water  in  all  proportions,  and 


PYRIDIN    AND    ITS    DERIVATIVES  485 

is  strongly  basic.  It  behaves  like  a  secondary  aminy  interacting 
with  methyl  iodid  to  form  methylpiperidin,  C5H10N  .  CH3. 

Piperidin  and  methylpiperidin  are  the  nuclei  of  a  number  of 
vegetable  alkaloids.  Coniin,  from  hemlock,  is  a  propylpiperidin; 
the  tropin  of  atropin,  and  ecgonin  of  cocain,  are  derivatives  of 
methylpiperidin  (p.  507). 

The  Pyridin  Homologues.—  These  are  the  alkyl  derivatives  of 
pyridin:  the  isomeric  picolins  or  methylpyridins,  C5H4N  .  CH3;  the 
isomeric  lutidins  or  dimethylpyridins,  C5H3N(CH3)2;  and  the 
collidins  or  trimethylpyridins,  C5H2N(CH3)3.  They  are  found  in 
bone  oil  and  coal-tar. 
HC=CHX 

Pyrrole,       I  /NH  or  C4H5N,  is  a  constituent  of  bone  oil. 

HC=CH 

It  is  formed  by  varied  reactions  of  organic  nitrogenous  substances, 
such  as  albumin  and  gelatin.  It  is  a  colorless  liquid,  smelling  like 
chloroform  and  showing  feebly  basic  properties. 

It  has  a  homologous  series  which  form  substitution  derivatives, 
among  which  is  tetra-iodo-pyrrole,  iodol,  U.  S.  P.,  C4HI4N,  a 
yellow-brown  powder  formed  by  ethereal  solution  of  iodin  acting  on 
pyrrole  in  the  presence  of  oxidizing  agents.  It  is  89  per  cent,  iodin 
and  is  used  in  medicine  as  an  alterative  and  antiseptic  substitute  for 
iodoform.  It  is  odorless,  tasteless,  slightly  soluble  in  water,  freely 
in  alcohol,  chloroform,  and  oils.  Dose:  8  to  15  gr.  (0.5-1  gm.). 
H2C-CH2 

Pyrrolidin,        I  /NH  (tetrahydropyrrde)  is  made  by  the 

H2C-CH/ 

action  of  nascent  hydrogen  on  pyrrole.  It  stands  to  pyrrole  in 
the  same  relation  that  piperidin  does  to  pyridin.  An  alkaline 
liquid,  it  resembles  piperidin  in  its  reaction.  It  is  the  nucleus  of  the 
hygrin  alkaloids  and  one  of  the  nuclei  of  nicotin  (p.  505). 

Prolin  or  «=Pyrrolidin  Carboxylic  Acid.  —  This  is  produced  by 
tryptic  digestion  or  hydrolysis  of  casein.  It  pre-exists  in  casein  as 
the  dipeptid  given  below: 


COOH 

The  formula  is  that  of  a  synthetic  product  of  leucin  and  pyrrol- 
idin  carboxylic  acid,  sometimes  called  leucylprolin. 

Piperazin  (Hexahydropyrazin  =  Diethylenediamiri).  —  When  2, 
3,  or  4  nitrogen  atoms  are  present  in  the  benzene  nucleus,  the  com- 
pounds are  known  as  di-,  tti-,  and  tetrazins.  The  diazins  are  three: 
ortho-,  meta-,  and  para-,  according  to  the  positions  of  the  nitrogen 


486  CYCLIC    COMPOUNDS 

atoms.     Each  has  a  series  of  substitution  derivatives.     Paradiazin, 

CH . N . CH 

|i         |       II     ,  is  known  under  the  name  pyrazin.     It  is  a  by-product 

CH . N . CH 

of  alcoholic  fermentation,  and  is  found  in  fusel  oil  or  commercial 

amyl  alcohol. 

When  6  more  hydrogen  atoms  are  taken  up  by  the  disengaged 

CH2 .  NH  .  CH2 
bonds,  the  substance  is  known  as  hexahydropyrazin,  \  \ 

CH2 .  NH  .  CH2 

or  HN  :  (C2H4)2  :  NH.  This  substance,  called  piperazin,  may  be 
prepared  by  reducing  paradiazin.  It  is  crystalline,  colorless,  sol- 
uble in  water,  deliquescent,  strongly  alkaline,  and  absorbs  carbon 
dioxid  from  the  air.  It  combines  with  uric  acid  to  form  piperazin 
urate,  which  dissolves  in  50  parts  of  water.  It  is  given  as  a  solvent 
for  uric  acid,  in  the  form  of  citrate  and  hydrochlorid.  Dose:  8  gr. 
(0.5  gm.).  It  is  best  given  alone,  as  it  is  incompatible  with  alum, 
copper  sulphate,  ferric  chlorid,  potassium  permanganate,  silver 
nitrate,  arsenic,  and  mercuric  iodid,  acetanilid,  alkaloidal  salts, 
carbolic  acid,  chloral  hydrate,  phenacetin,  picric  acid,  quinin,  so- 
dium salicylate,  tannic  acid,  spirits  nitrous  ether. 

CO  CO 

Indigotin    (C6H4<NH>C  :  C<NH>C6H4)    (Indigo  Blue).- 

This  is  the  blue  constituent  of  ordinary  indigo  formed  from  the 
yellow  glucosid,  indican,  found  in  certain  plants.  By  heating  with 
dilute  acids  or  by  fermentation  indican  gives  indigo  blue.  Several 
reactions  produce  it  synthetically— that  is,  by  oxidation  of  indoxyl 
or  from  cinnamic  acid. 

Indoxyl  sulphuric  acid  is  a  constituent  of  the  urine,  sometimes  in 
such  proportion  that  oxidizing  agents  give  the  urine  a  blue  color 
from  the  formation  of  indigo. 

When  indigo  blue  is  oxidized,  it  is  converted  to  isatin,  which  is 
yellowish  brown.  This  property  makes  it  useful  as  a  test  for  nitric 
acid.  It  also  loses  its  color  by  the  action  of  reducing  agents,  as  in 
the  indigo  test  for  glucose. 

Indol  (C6H4<CH>CH)   (Benzopyrrole).—This  substance  is  a 

combination  of  the  benzene  and  the  pyrrole  rings,  as  shown  by 
the  structural  formula.  It  can  be  produced 
synthetically  by  several  reactions.  The  most 
interesting  method  of  formation  is  that  by 
putrefaction  of  proteins  in  the  intestines 
during  digestion.  Part  of  it  remains  in  the 
fecal  mass  and  part  is  absorbed  and  carried 
indoi.  by  the  portal  circulation  to  the  liver  to  be 


PYRIDIN    AND    ITS    DERIVATIVES  487 

oxidized  to  indoxyl,  C6H4<    ^H  '>CH.     This  readily  combines 

with  potassium  sulphate  to  form  potassium  indoxylsulphate, 
C6H4 .  NH  .  CHCKSO4.  This  is  the  indican  or  uroxanthin  eliminated 
by  the  urine.  It  is  not  the  glucosid  referred  to  above,  but  an  ether- 
eal salt  or  conjugate  sulphate. 

When  hydrochloric  acid,  with  a  trace  of  potassium  chlorate  or  of 
ferric  chlorid,  is  added  to  urine,  this  indican  breaks  up  into  potas- 
sium sulphate  and  indigo  blue,  the  latter  being  formed  by  oxidation 
of  the  indoxyl: 

C6H4NH  .  CH  .  KSO4     +     H2O     = 

Indican. 

KHS04     +      C6H4  .  NH  .  C(OH)  .  CH 

Indoxyl. 

2(C8H6NOH)      +      20  C16H10N202     +      2H2O. 

Indoxyl.  Indigo  blue. 

This  reaction  is  made  use  of  in  urinary  analysis  for  indican  by 
Jafje's  method  (p.  581).  In  testing  for  indican  in  the  urine  by  this 
method  the  oxidation  may  be  carried  too  far  and  the  indigo  blue  be 
converted  to  yellowish  isatin. 

The  other  conjugate  sulphates  found  in  the  urine  in  traces  are  the 
potassium  and  sodium  compounds  of  the  ester-sulphuric  acids  of 
skatoxyl,  phenol,  catechol,  quinol,  and  paracresol.  They  vary  in 
amount  inversely  as  the  mineral  sulphates;  and  after  poisoning  by 
carbolic  acid  all  of  the  sulphuric  acid  is  taken  by  the  phenol  com- 
pound at  the  expense  of  the  mineral  sulphates. 


Skatol    fdHX^VT    3'>CH)    (B-Methylindol).—Ska.to\  is    a 


methyl  substitution  of  indol.     The  odor  characterized  as  fecal  is 
due  to  the  presence  of  skatol  with  indol.     The 

skatol  exceeds  the  indol  as  a  product  of  the     yr\ 

putrefaction  of  proteins.     It  can  be  prepared  1  ^ 

by  the  reduction  of  indigo.     Like  indol,  it  is     k        J\         ) 
partly   absorbed   from   the   fecal    mass   in   the  NH 

intestines,   and  is   excreted   by   the   kidney  as  skatol. 

potassium  skatoxylsulphate. 

Jaffe's  test  will  yield  a  red  or  violet  color  when  the  skatoxyl  com- 
pound is  in  excess.  This  color  is  called  skatol  red.  Such  urines, 
when  oxidized  by  nitric  acid,  turn  red,  violet,  and  blue. 

Quinolin  (C8H7N)  (chinolin}  is  the  parent  substance  of  a  group 
closely  related  to  the  vegetable  alkaloids  and  known  as  the  quinohn 
or  benzopyridin  bases.  It  is  in  coal-tar  and  bone  oil,  can  be  pre- 
pared by  distilling  quinin  and  cinchonin  with  potash,  and  syn- 


488  CYCLIC    COMPOUNDS 

thetically  by  heating  anilin,  glycerin,  and  sulphuric  acid  in  the 
presence  of  nitrobenzene. 

It  is  a  colorless  oil  with  a  characteristic  odor,  sparingly  soluble 
in  water,  forming  crystalline  salts  with  the  acids. 

For  various  reasons  the  constitution  of  pyridin,  C5H5N,  and 
quinolin,  C9H7N,  is  believed  to  have  the  same  relation  as  that  of 
benzene,  C6H6,  and  naphthalin,  Q0H8,  being  represented  by  the 
formulas  below,  showing  quinolin  has  a  benzene  and  pyridin  ring 
condensed: 

CH 


H 


Pyridin.  Quinolin.  Isoquinolin. 


Isoquinolin  is  very  like  quinolin  in  chemical  properties,  but  dif- 
fers physically.  It  is  found  in  coal-tar  with  quinolin.  In  consti- 
tution it  differs  from  quinolin  in  that  the  benzene  ring  is  attached  by 
the  ft  andr  positions,  and  not  by  the  a  and  /?,  as  quinolin. 

Thallin  (C9H6 .  O  .  CH3 .  N  .  H4  or  C10HUNO)  (Tetrahydro- 
paramethyloxyquinolin). — Among  the  synthetic  basic  substances 
made  from  quinolin  and  containing  its  nucleus  are  thallin  and 
kairin.  Thallin  receives  its  name  from  the  intense  green  color  it 
forms  with  ferric  chlorid.  Its  sulphate  is  in  yellowish  needles, 
aromatic,  bitter,  and  soluble  in  water.  In  medicine  it  is  used  as  a 
transitory  antipyretic  and  antiseptic.  Dose:  2  gr.  (0.13  gm.) 
hourly. 

PURINS  AND  URIC  ACID 

Uric  acid  (C5H4N4O3)  (trioxypurin)  occurs  in  the  tissues  of  the 
body,  the  blood,  and  the  human  urine,  in  small  amount,  combined 
with  sodium,  potassium,  ammonium,  calcium,  and  magnesium. 
It  is  found  as  solid  ammonium  urate  in  the  excrement  of  reptiles  and 
birds. 

Preparation. — Having  pulverized  the  excrement  of  a  serpent, 
it  should  be  boiled  with  sodium  hydroxid  in  a  porcelain  dish  until  all 
the  ammonia  has  been  driven  off.  The  liquid,  having  been  filtered 
while  hot,  is  poured  into  hydrochloric  acid.  As  it  cools,  a  fine  crys- 
talline powder  of  uric  acid  falls  (Plate  7,  Fig.  5). 

It  can  be  prepared  by  synthesis  by  heating  urea  with  glycocoll 
at  200°  C.  (392°  F.).  When  decomposed,  urea  is  one  of  the 
products.  Although  uric  acid  does  not  contain  the  acid  group 
COOH,  it  has  3  groups  of  HNCO,  which  give  it  combining 
power  toward  bases  and  blood-serum. 


PURINS    AND    URIC    ACID  489 

Properties. — Almost  insoluble  in  water,  uric  acid  is  wholly  in- 
soluble in  alcohol  and  ether,  but  soluble  in  warm  glycerin.  Its 
solubility  is  much  reduced  when  some  other  acid  is  present  in  sol- 
ution. It  is  a  weak  acid  with  2  atoms  of  replaceable  hydrogen, 
forming  2  classes  of  salts,  like  the  acid  sodium  salt,  NaC5H3N4O3, 
and  the  normal  sodium  salt,  Na2C5H2N4O3.  The  normal  salts 
are  soluble,  but  the  acid  salts  are  soluble  to  a  slight  degree  only; 
both  are  kept  in  solution  in  urine  by  the  disodium  phosphate. 
Two  salts  with  organic  bases  are  much  more  soluble — piperazin 
urate  and  lysidin  urale;  hence  the  use  of  these  bases  to  dissolve  uric- 
acid  gravel. 

Murexid  Test. — In  a  porcelain  dish  place  some  uric  acid  or  a 
urate.  Moisten  with  nitric  acid  and  evaporate  at  a  gentle  heat.  If 
no  ammonia  be  present,  a  yellow  stain  of  alloxantin  is  left. 

2C5H4N4O3  +  2H2O  +  O2  =  2C4H2N2O4  +  2CON2H4 

Uric  acid.  Alloxan.  Urea. 

Continued  heat  splits  alloxan  into  alloxantin,  parabanic  acid, 
and  carbon  dioxid: 

3C4H2N204    =    C8H4N407    +    C3H2N203    +    CO2. 

Alloxan.  Alloxantin.  Parabanic  acid. 

The  yellow  residue  yields  a  red-purple  color  with  ammonia,  due 
to  ammonium  purpurate  or  murexid: 

C8H4N407    +    2NH3          C8H8N606    +    H2O. 

Alloxantin.  Murexid. 

As  xanthin  and  guanin  both  yield  the  red  color,  add  i  drop  of 
sodium  hydroxid  and  the  uric-acid  red  turns  blue.  Moisten  with 
water  and  evaporate  to  dryness;  the  color  disappears. 

Experiment  i. — To  a  mixture  of  50  c.c.  of  urine  and  2.5  c.c.  of 
concentrated  solution  of  sodium  carbonate  add  5  c.c.  of  a  saturated 
ammonium  chlorid  solution.  On  standing,  ammonium  urate  is 
precipitated. 

Experiment  2. — If  a  small  quantity  of  uric  acid  be  shaken  with 
water,  it  does  not  dissolve.  Adding  dilute  potassium  hydroxid,  the 
soluble  dipotassium  urate  is  formed.  Dilute  acid  will  precipitate 
uric  acid  again. 

Purin  Bodies. — Uric  acid  is  the  most  highly  oxidized  member 
of  a  series  of  compounds  considered  to  be  derivatives  of  a  syn- 
thesized substance,  C5N4H4,  called  purin.  The  other  members  of 
the  series,  being  basic,  are  called  alloxuric  bases  or  xanthin  bases, 
after  the  second  member  given  below.  The  nucleins  found  in  cell 
nuclei  decompose  by  acids  and  enzyms  in  such  a  way  as  to  justify 


490  CYCLIC    COMPOUNDS 

the  view  that  they  consist  of  protein  combined  with  nucleic  acid. 
The  nucleic-acid  molecule  contains  some  of  the  purin  and  pyrim- 
idin  bases  united  with  orthophosphoric  acid.  As  purin  bodies 
are  products  of  the  decomposition  of  nucleins,  they  may  be  termed 
nuclein  bases.  They  are  considered  to  be  intermediate  stages  of 
oxidation  of  nucleoproteins  on  the  way  to  form  uric  acid. 

Uric  acid,          C5H4N4O3  .....  Heteroxanthin,  C5H3(CH3)N4O2. 
Xanthin,  C6H4N4O2  .....  Paraxanthin,      C5H2(CH3)3N4O2. 

Hypoxanthin,  C5H4N4O   .....  Theobromin,      C6H2(CH3)2N4O2. 

,  Theophyllin,      C5H2(CH3)2N4O2  ; 
Guanin,  C6H6N6O   ....  {          . 


Adenin,  C5H5N5      .....  Epiguanin,         C6H4(CH3)N5O. 

It  will  be  seen  that  in  the  second  column  are  the  methyl 
derivatives  of  the  bodies  in  the  first  column. 

The  purin  bodies  occur  together,  being  found  in  the  same  sit- 
uation and  in  small  amount  in  the  urine,  the  blood,  and  many  of 
the  tissues.  In  rare  cases  the  xanthin  of  the  urine  separates  in  the 
bladder  and  forms  the  xanthin  calculus.  They  are  found  in  all 
meat  extracts,  to  which  they  impart  a  stimulating  quality,  but  no 
food  value.  Some  meat  extracts  contain,  in  addition,  proteins, 
which  are  nutritive. 

The  structure  of  these  bases  and  their  close  kinship  to  uric  acid 
will  be  better  understood  if  the  following  graphic  formulas  are 
studied.  The  first  two  are  purely  hypothetic  bodies: 

N=CH 

N-C  |       | 

I      |  HC    C—  NH 

C    C  N.  II     I)      \ 

I  V  /CH 

tf-C-N 


N—  C 

Alloxan  nucleus.  Urea  nucleus.  Purin. 

Uric  acid  and  the  xanthin  bases  may  be  considered  as  substi- 
tution products  of  purin  by  the  radical  hydroxyl,  amido-,  imido-, 
or  methyl  groups.  The  position  of  the  substituted  radicals  is 
indicated  according  to  the  numbers  in  the  diagram  of  the  purin 
nucleus  given  below.  The  purin  nucleus  is  made  up  by  joining  the 
carbon-nitrogen  nuclei  of  urea  and  alloxan  given  above. 


»C    6C— N' 
3N— C— N»/ 

4 
Purin  nucleus. 


PURINS    AND    URIC    ACID 


491 


Hypoxanthin  is  6  oxypurin: 
HN—  CO 

HC     C-NH 


Xanthin  is  2.6  dioxypurin: 
HN—  CO 
CO  C—  NH 


Guanin  is  2  amino-,  6  oxypurin: 
HN—  CO 

.C     C—  NH 

>H 

-N 


H2N.C     C— ] 

IX 


Uric  acid  is  2.6.8  trioxypurin: 


HN—  CO 

C—  NH 


CO 


Adenin  is  6  aminopurin: 
N—  C.NH, 

HC    C—  N 

I      >CH 
—  C—  NH 

Theobromin  is   3.7    dimethyl  - 
xanthin: 

HN—  CO 


CO 


C-N. 


HN- 


H 


CH 


CH3 


3N-C-N 


Theobromin,  3.7  dimethylxanthin,  C5H2(CH3)2N4O2,  occurs  in 
the  seed  of  Theobroma  cacao,  from  which  chocolate  is  made. 
Theophyllin  occurs  in  tea  used  as  a  beverage,  and  it  may  be  pre- 
pared synthetically  from  dimethyluric  acid. 

Caffein  (thein,  guaranin),  1.3.7  trimethylxanthin,  C5H(CH3)3- 
N4O2,  is  found  in  tea,  coffee,  guarana,  and  other  stimulating 
plants.  It  may  be  formed  from  trimethyluric  acid.  It  is  soluble 
in  80  parts  of  water,  35  of  alcohol. 

Caffein  titrated  contains  50  per  cent,  of  caffein.  It  is  a  white 
powder  with  an  acid  taste,  soluble  in  25  parts  of  water.  Dose:  2  to 
10  gr.  (0.13-0.65  gm.). 

Murexid  Test.  —  To  0.5  gm.  of  caffein  in  a  porcelain  dish  add  a 
few  cubic  centimeters  of  strong  fuming  nitric  acid  and  evaporate  to 
dryness.  A  yellow  stain  is  left,  which  on  moistening  with  am- 
monium hydroxid  becomes  purple. 

Pyrimidin  Bases.  —  When  the  nucleic  acids  break  up,  the  prod- 
ucts are  the  purins  referred  to  above  and  the  bases  uracil,  thymin, 
and  cytosin,  which  are  derivatives  of  pyrimidin,  C4H4N2.  Pyrim- 
idin is  obtained  by  splitting  off  one  side  of  purin.  Uric  acid  can 
be  formed  synthetically  from  these  derivatives.  The  relationship 
is  expressed  in  the  following  formulas: 
(i)  N—  C  (6)  HN—  CO 

I!  I      I 

C  OC     CH 


(2)  C     C  (5) 


I      I 
N=C 


x 
(3)  N=C  (4) 

Pyrimidin  nucleus. 


I      II 
HN—  CH 

Uracil. 


HN—  CO 

I      ! 

OC     C—  NHV 
I      II          >CO 
/ 


HN—  C—  NH 

Uric  acid. 


492  CYCLIC    COMPOUNDS 

Uracil,  C4H4N2O2,  has  been  found  in  the  nucleoproteins,  and  so 
has  thymin,  C4H3N2O2 .  CH3,  which  is  methyluracil.  Cytosin, 
C4H5N3O,  is  a  constant  cleavage  product  of  the  nucleic  acids.  It  is 
so  intimately  related  to  the  purin  group  that  it  is  supposed  to  be  the 
mother-substance. 

Uric  acid  in  the  urine  is  derived  from  two  sources — the  internal 
and  the  external,  or  endogenous  and  exogenous.  The  endogenous 
uric  acid  comes  from  the  nucleins  *f  the  body  cells  ani  their 
decomposition  products,  the  purin  bases.  The  quantity  for  each 
individual  is  fairly  constant  and  uninfluenced  by  food.  The 
exogenous  uric  acid  arises  from  the  nucleins  and  purin  bases  con- 
tained in  the  food.  It  is,  therefore,  an  addition  to  the  normal  quan- 
tity and  is  dependent  entirely  on  the  amount  of  combined  and  free 
oxypurins  and  aminopurins  in  the  food.  These  are  abundant  in 
sweetbreads  (thymus  gland),  liver,  kidney,  meat  soups,  peas,  beans, 
asparagus,  heavy  wines,  meats,  and  fish.  A  purin-free  diet  may  be 
made  of  bread,  butter,  milk,  sugar,  eggs,  potatoes,  rice,  and  green 
vegetables.  When  the  diet  is  regulated  so  that  there  are  no  purins 
in  the  food,  the  output  of  uric  acid  is  materially  lessened.  Theo- 
bromin,  caffein,  and  other  methylpurins  in  food  have  no  effect 
on  the  uric-acid  elimination,  though  they  increase  the  amount  of 
purin  bases,  such  as  xanthin  and  hypoxanthin,  in  the  urine.  In 
the  process  of  metabolism  of  cell  nuclei  in  the  liver,  kidney,  and 
other  organs,  uric  acid  is  a  stage  between  the  purin  bases  and  a 
further  oxidation  product.  This  end-product  may  be  urea  or 
allantoin  or  glycocoll  or  CO2  and  H2O. 

Nuclein 

protein nucleic  acid 

purin  and  pyrimidin  bases phosphoric  acid. 

Purin  bases  are  partly  oxidized  by  the  liver  to 

uric  acid,  which  is  again  partly  oxidized  to 
urea  of  urine. 

Some  of  the  purin  bases,  such  as  adenin,  under  certain  con- 
ditions of  the  body  have  a  marked  toxic  action.  They  are  sup- 
posed to  be  factors  in  the  production  of  febrile  temperatures. 
Other  nitrogenous  waste  substances,  such  as  leukomains,  creitin, 
etc.,  resulting  from  metabolism  of  cell  protoplasm,  have  their 
formation  augmented  by  a  diet  rich  in  proteins. 

In  the  urine  the  ratio  of  purin  bases  to  uric  acid  is  about  i  :  10. 
Expressed  in  terms  of  the  nitrogen  content,  uric  acid  N  is  to  that 
of  the  purin  bases  as  4  :  i.  The  total  amount  excreted  daily  varies 
between  0.0286  and  0.0561  gm. 


PURINS    AND    URIC    ACID 


493 


Hall's  Purinometer.— For  clinical  purposes  it  is  sometimes 
desirable  to  determine  the  total  sum  of  purin  nitrogen  in  the  urine, 
including  that  of  uric  acid.  A  simple  and  easy  method  is  that  of 
Walker  Hall.  His  purinometer  estimates  by  volume  the  amount  of 
silver  purins  precipitated  by  ammoniosilver  nitrate. 

T\»o  solutions  are  required  for  solution  No.  i  :  Mix  100  c.c.  of 
Ludwig's  magnesia  mixture,1  100  c.c.  of  ammonia  (20  per  cent.), 
and  5  gm.  of  finely  powdered  talc. 

Solution  No.  2  is  a  mixture  of  silver  nitrate,  i  gm.;  strong 
ammonia,  100  c.c.;  finely  powdered  talc,  5  gm.;  and  100  c.c.  of 
water.  No.  i  precipitates  the  phosphates;  No.  2  precipitates  the 
purins,  the  silver  chlorid  being  kept  in  solu- 
tion by  the  ammonia.  The  object  of  the  talc 
is  to  make  the  precipitate  heavy  and  definite. 

Directions. — Having  measured  and  mixed 
the  total  urine  of  the  day,  100  c.c.  is  made 
free  of  albumin  (if  present)  by  slightly  acid- 
ulating, boiling,  and  filtering.  With  the  stop- 
cock at  right  angles,  90  c.c.  of  urine  and  20 
c.c.  of  solution  No.  i  are  poured  into  the 
graduated  tube  -(Fig.  82)  and  the  instrument 
inverted  several  times.  The  phosphates  are 
precipitated  and  the  stopcock  is  opened  ver- 
tically. In  ten  minutes  the  phosphates  settle 
into  the  lower  chamber  of  the  tube  and  the 
cock  is  again  turned  off  at  right  angles,  and 
No.  2  solution  added  up  to  100  c.c.  By  free 
inversion  of  the  tube  several  times  the  pale- 
yellow  silver  purin  is  freed  of  the  white  silver 
chlorid.  If  this  does  not  occur,  a  few  drops 
of  strong  ammonia  may  be  added.  The  in- 
strument is  placed  in  a  dark  cupboard  for  twenty-four  hours, 
when  the  number  of  cubic  centimeters  occupied  by  the  precip- 
itate is  read  off. 

A  table  is  furnished  with  each  instrument,  which  shows  the 
nitrogen  percentage  yielded  by  each  cubic  centimeter  of  precipitate. 
This  factor,  multiplied  by  the  total  cubic  centimeter  of  urine  divided 
by  100,  gives  the  total  purin-nitrogen. 

Example:  The  silver  purin  precipitate  amounted  to  9  c.c. 
The  table  stated  that  9  c.c.  =  0.0175  per  cent,  purin-nitrogen. 
The  total  daily  urine  was  1 2 10  c.c.  Then,  0.0175  X  12.1=  °-2II75 
purin-nitrogen. 

Creatin,  C4H9N3O2. — Associated  with  the  purin  bases  in  the 

1  Ludwig's  magnesia  mixture  is  composed  of  magnesium  chlorid,  no  gm.; 
ammonium  chlorid,  no  gm.;  ammonia,  250  gm.;  water,  to  i  L.  Mix. 


FIG.  82. — Purinometer. 


494  CYCLIC    COMPOUNDS 

nitrogenous   extractive   of   muscular  tissue  is   creatin   or   methyl- 

NH 
guanidin  acetic  acid.     It  is  a  derivative  of  guanidin,  NH  .  C<MTr2, 

i\  ±12 

which  is  an  oxidation  product  of  guanin.  The  structural  formula 
of  creatin  is  that  of  a  complex  amino-acid. 

NH    C<NH2 

^N(CH3).CH2.COOH. 

It  is  easily  obtained  as  a  product  of  metabolism  from  beef  heart  or 
the  flesh  of  fowl  by  extraction  with  warm  water.  As  a  by-product 
in  making  "  beef  extract "  it  crystallizes  with  the  residue  of  meat 
juice.  Boiled  with  baryta  water  or  other  alkali,  it  breaks  up  into 
urea  and  sarkosin.  By  prolonged  boiling  with  dilute  hydro- 
chloric acid  it  loses  a  molecule  of  water  and  becomes  the  anhydrid 
creatinin,  C4H7N3O,  an  ingredient  of  the  juice  of  flesh,  also  of  the 
blood  and  the  urine.  By  its  reducing  action  on  alkaline  copper 
solution  when  boiled  it  is  the  source  of  a  fallacy  in  testing  for 
glucose  in  the  urine.  Creatinin  is  a  strong  base  forming  a  crys- 
talline double  chlorid  with  zinc  chlorid  in  alcoholic  solution. 

/CO.NH 
Allantom,     HN<CO    CH    H^.    CQ    NH  ,     occurs     in    the 

allantoic  fluid  of  cows,  the  urine  of  calves,  dogs,  and  cats,  newborn 
children,  and  pregnant  women.  It  is  a  product  of  enzym  action 
on  uric  acid  in  liver,  spleen,  and  pancreas.  Crystalline  and 
sparingly  soluble  in  water,  if  heated  with  alkalis  it  breaks  up  to 
NH3 .  CO2,  oxalic  and  acetic  acids. 


F  o 


AMMONIA  DERIVATIVES 

.£  v 

AMIDS,  AMINS,  AMINO-ACIDS,  AND  ALKALOIDS 

AMMONIA,  NH3,  plays  a  part  in  organic  compounds  by  the  sub- 
stitution of  i  or  more  univalent  hydrocarbon  radicals  for  an  atom 
of  its  hydrogen.  When  the  radical  is  basic, — that  is,  such  as  are 
found  in  the  alcohols, — the  product  is  called  an  amin;  when  the 
radical  is  acid,  the  compound  is  called  an  amid. 

Amids  are  neutral  in  reaction.  They  are  produced  when 
amidogen,  NH2,  replaces  hydroxyl,  HO,  in  a  carbon  acid.  This 
is  the  result  of  a  reaction  between  the  HO  of  the  COOH  group 
and  NH3.  Thus: 


CH3.COJOH     +      H|NH2     =      CH3 .  CONH2     +      H2O. 

Acetic  acid.  Acetamid. 


AMIDS  495 

When  ammonium  acetate,  NH4C2H3O2,  is  heated,  H2O  escapes 
and  acetamid,  NH2C2H3O,  remains  as  soluble  crystals  with  a 
mousy  odor.  Other  atoms  of  hydrogen  may  be  displaced  by  re- 
action with  NH3,  and  diacetamid  produced.  In  a  double  molecule, 
2NH3  or  N2H6,  the  radical  carbonyl  may  be  substituted  for  2 
hydrogen  acids,  thus  making  carbamid  or  urea: 

/H  /C2H30  /C2H30 

N^H  Nf  H  N^-cX<> 

\H  \H  \H 

Acetamid.  Diacetamid.  Carbamid. 

Amid  and  Stable  Nitrogens. — When  an  amid  is  boiled  with 
a  caustic  alkali,  the  stronger  base  displaces  the  weaker  NH2  from 
its  union  with  the  acid  radical.  Thus: 

CO(NH2)2     +      2NaHO      =      Na2CO3     +      2NH3. 

Urea.  Sodium  carbonate. 

But  the  alkali  has  no  affinity  with  the  basic  radical  in  the  amins 
and  amido-acids,  and  hence  their  nitrogen  is  not  displaced  by  this 
means.  It  is  stable  and  requires  the  action  of  strong  sulphuric 
acid  and  potassium  sulphate  to  form  ammonium  sulphate,  as  in 
KjeldahPs  method  (p.  365). 

Nitrous  acid  (HNO2)  has  the  power  of  substituting  OH  for 
and  breaking  up  all  NH2  groups,  whether  amid,  amin,  or  amido- 
acids.  Thus,  if  a  mixture  of  ethylamin  hydrochlorid,  C2H5NH2, 
HC1,  and  potassium  nitrate  be  added  to  glacial  acetic  acid,  the 
nascent  nitrous  acid  causes  2  atoms  of  nitrogen  to  be  evolved  and 
ethyl  alcohol,  C2H5 .  HO,  is  left.  Sodium  hypobromite,  NaOBr, 
in  alkaline  solution  splits  off  N  from  NH2  groups,  but  only  to 
the  extent  of  90  per  cent. ;  hence  the  calculation  of  nitrogen  contents 
by  this  method  is  not  so  accurate  as  by  that  of  Kjeldahl  (p.  365). 

Urea  (carbonyl  diamid,  carbamid)  is  present  in  the  urine  of 
mammals  and  of  carnivorous  birds  and  reptiles;  also  in  the  blood, 
the  muscles,  and  various  animal  fluids.  Its  constitution  has  been 
made  out  by  the  synthetic  reactions  given  on  pp.  193  and  200.  It  is 
the  chief  solid  constituent  of  human  urine,  and  is  generated  mainly 
in  the  liver,  from  nitrogenous  waste  substances.  The  nitrogen  of 
the  urea  parts  from  the  muscular  tissue  as  ammonium  lactate. 
This  NH4C3H5O3  changes  in  the  tissues  to  carbonate.  The  ammo- 
nium carbonate  is  dehydrated  by  the  liver  cells,  forming  first  am- 
monium carbamate  and  lastly  urea: 

,      TT r\__^ 

le 

Ammonium  carbonate.  Ammonium  carbamate.  Urea. 

It  occurs  in  white  or  colorless  needles  with  a  cool  and  bitter  taste. 
It  melts  at  132°  C.  (270°  F.)  and  readily  dissolves  in  water  and 


496  CYCLIC    COMPOUNDS 

alcohol.     When  heated  to   120°  C.  (248°  F.)  in  the  presence  of 
water  it  forms  ammonium  carbonate: 

CO  .  N2H4         +          2H2O  (NH4)2CO3. 

When  heated  without  water,  it  breaks  up  into  cyanuric  acid  and 
ammonia: 

3CON2H4  C3H3N303        +         3NH3. 

Cyanuric  acid. 

Fuming  nitric  acid  decomposes  it  into  nitrogen  and  carbon 
dioxid: 

CO.N2H4   +   2HNO2   =    CO2   +   N2   +    2H2O. 

Hypochlorites  and  hypobromites  have  a  similar  effect,  giving  off 
CO2  and  N: 

CO  .  N2H4  +  3NaOBr  =  CO2  +  N2  +  2H2O  +  3NaBr. 

If  the  CO2  be  fixed  by  passing  through  alkaline  solution,  then 
the  free  nitrogen  may  be  measured  and  an  estimate  made  of  the 
quantity  of  urea  required  to  produce  that  amount  (p.  592). 

The  solution  of  urea  is  neutral  in  reaction,  though  its  relation 
to  acids  is  basic.  It  combines  with  one  equivalent  of  acids  to 
form  salts,  the  most  characteristic  of  which  is  urea  nitrate,  CO- 
(NH2)2,  HNO3,  crystallizing  in  glistening  plates.  It  unites  with 
metals  to  form  such  compounds  as  HgO  .  CO(NH2)2  and  HgCl2- 
CO(NH2)2. 

Tests. — Nitrate. — Evaporate  fresh  urine  on  a  water-bath  to  a 
syrupy  consistence.  On  cooling,  add  strong  nitric  acid,  and  crys- 
tals of  urea  nitrate  will  appear.  Having  separated  the  crystals 
by  filtration,  they  are  dissolved  in  boiling  water  and  the  solution 
treated  with  barium  carbonate.  This  forms  barium  nitrate  and 
free  urea  in  the  solution,  which  is  then  evaporated  to'  dryness  and 
the  residue  treated  with  hot  alcohol,  thus  extracting  the  urea  and 
leaving  the  barium  nitrate.  Filtration  gives  a  clear  solution  which, 
on  evaporation,  deposits  crystals  of  urea. 

Biuret. — The  urea  formed  above  is  carefully  heated  in  a  test- 
tube  to  about  160°  C.  (320°  F.)  until  no  more  ammonia  comes 
off.  It  is  then  allowed  to  cool.  The  residue  is  a  substance  called 
biuret,  which,  if  treated  with  a  few  drops  of  potassium  hydroxid  and 
of  copper  sulphate,  will  yield  a  violet-red  color  (Plate  8,  Fig.  7): 

/NHi 
C0 

C0< 

>NH 
CO( 


CO/ 


Urea.  Biuret. 


AMINS  497 

Two  molecules  of  urea  combine,  excluding  NH3  to  form  biuret. 

Urea  has  diuretic  properties  esteemed  of  value  in  the  treatment 
of  dropsies.  Dose:  10  to  20  gr.  every  hour  in  water.  It  is  incom- 
patible with  chloral  hydrate  and  lead  acetate. 

Formamid,  N(CHO)H2,  is  a  colorless  liquid  made  by  heating 
an  alcoholic  solution  of  ammonia  with  ethyl  formate.  It  unites 
with  chloral,  forming  chloralamid,  N(CHO)H2C2HC13O,  a  recently 
introduced  hypnotic.  It  occurs  in  colorless,  bitter  crystals,  sol- 
uble in  water  and  alcohol,  and  decomposable  by  hot  solvents. 
Dose:  15  to  45  gr.  It  is  incompatible  with  silver  nitrate  and  the 
alkalis. 

Amins  are  said  to  be  primary,  secondary,  or  tertiary,  according 
to  the  number  of  atoms  of  hydrogen  in  NH3  which  have  been  re- 
placed by  the  basic  radical.  The  production  is  illustrated  in  the 
three  classes  of  amins  of  ethyl,  C2H5,  from  ethyl  bromid,  C2H5Br, 
by  the  following  series  of  equations: 

C2H5Br  -f  NH3  =  NH2 .  C2H5  .  HBr— *NH2 .  C2H5,  Ethylamin; 

C2H5Br-f  NH2.C,H5  =  NH(C2H6)2HBr  —>NH(C2H6)2,  Diethylamin; 
C2H5Br  +  NH(C2H5)2  =  N(C2H6)3  .  HBr  — »-N(C2H5)3  =  Triethylamin. 

The  salts  in  the  middle  column  treated  with  KOH  form  KBr  + 
H2O  and  the  amins  of  the  last  column. 

The  following  formulas  represent  the  constitution  on  the  am- 
monia plan: 

N— H  X   T-C2H5  X   T— C2H5  TV   T-C2H5  TV   T-CH,  MethyK 

-H    \J  -H2        rSj  -C  H      \J  -C  H     \J  -C,H5  Ethyl    ^amin. 

_H  1  N  -H        1  N  _H        1  N  _C2H*  1    1  -C4H9  Butyl    / 
Ammonia.     Ethylamin.            Diethylamin.     Triethylamin. 

They  are  a  very  important  class  of  basic  substances,  soluble 
in  water,  alkaline  in  reaction,  and  have  a  strong  odor  similar  to 
ammonia.  Like  ammonia,  also,  they  precipitate  metallic  salts 
and  react  with  acids  to  form  salts  without  elimination  of  water. 

NH3          +          HC1  NH4C1. 

N(C2H5)3          +          HC1  N(C2H5)3HC1 

Triethylamin.  Triethylamin  chlorid. 

An  amin  is  the  result  of  a  reaction  between  the  OH  group  of 
an  alcohol  and  NH3.  Thus: 

C2H5|OH + HjNH2     =      C2H5.NH2     +     H2O. 

Ethyl  alcohol.  Ammonia.  Ethylamin. 

Another  view  of  the  constitution  of  the  amins  is  to  consider 
them  as  hydrocarbons   with  the  hydrogen  replaced  by   nitrogen 
32 


498  CYCLIC    COMPOUNDS 

radicals.  The  primary  amins  having  the  amino  group  NH2  in 
them  are  called  amino-compounds;  thus,  methylamin,  NH2CH3,  is 
amino-methyl.  The  secondary  amins  are  called  imins  or  imino- 
compounds,  from  the  imino  group,  NH;  thus,  dimethylamin, 
NH(CH3)2,  is  imino-dimethyl. 

Carbylamin   or  Isonitril    Reaction.— When   warmed   with 

chloroform  and  alcoholic  potash,  ethylamin  and  all  primary  amins 
quickly  undergo  a  change  to  carbylamins  or  isonitrils  which  have 
an  unbearable,  characteristic  odor: 

C2H5 .  NH2  +  CHC13  +  3KOH  =  C2H5NC  +  3KC1  +  3H2O. 

Ethylamin.  Carbylamin. 

Trimethylamin  is  an  isomer  of  propylamin,  N(CH3)3.  It  is 
found  in  fish  brine,  and  is  a  product  of  putrefactive  decomposi- 
tion in  brain  tissue,  muscle  tissue,  and  starch  paste.  In  the  form  of 
a  10  per  cent,  solution  it  is  used  in  the  treatment  of  rheumatism. 
It  is  a  colorless  liquid  with  a  strong,  fishy,  and  ammoniacal  odor. 
Dose:  15  to  45  min. 

Urotropin  (for min)  is  a  condensation  product  when  ammonia 
reacts  with  formaldehyd,  6CH2O  +  4NH3=  (CH2)6N4  +  6H2O. 
The  odor  of  formaldehyd  disappears  in  the  process.  It  is  hexa- 
methylenamin,  (CH2)6N4,  U.  S.  P.  It  occurs  in  soluble  crystals, 
used  as  a  diuretic  and  solvent  for  uric-acid  concretions.  It  is 
said  to  act  as  an  antiseptic  by  liberating  formaldehyd  in  the  urinary 
passages.  Dose:  '/J  to  15  gr.  (J-i  gm.). 

Amino=acids  are  regarded  as  being  produced  by  substituting 
the  amino  group,  NH2,  for  HO  in  the  alcohol  group  of  an  oxyacid. 

COOH .  CHjOH  +  H;NH2  =  COOH  .  CH2NH2  +  H2O. 

Oxyacetic  acid.  Amino-acetic  acid. 

In  reaction  they  are  amphoteric.  Since  the  acid  and  the  base  are 
not  in  direct  union,  but  joined  to  different  carbon  atoms,  each  group 
retains  its  own  reaction.  They  are  basic  because  they  have  the 
NH2,  and  are  acid  at  the  same  time  because  of  the  COOH  group. 
When  chemically  inactive  these  neutralize  each  other,  but  acting  with 
outside  ions  they  form  anions  and  kations  according  to  the  nature 
of  the  exciting  ion.  They  are  more  stable  than  the  amids  and 
form  some  optically  active  physiologic  compounds.  The  protein 
molecule  is  composed  almost  entirely  of  them,  the  acid  group 
of  one  linked  to  the  amino-  (basic)  group  of  the  next  like  a  train 
of  cars.  Their  constitution  and  relation  to  amids  are  shown  below: 

CH3  CH3  CH2OH  CH2(NH2) 

III  I 

COOH  CO(NH2)          COOH  COOH 

Acetic  acid.  Acetamid.  Oxyacetic  acid.  Amino-acetic  acid. 


AMINO-ACIDS  499 

As  the  NH2  may  be  joined  to  any  C  atom  in  a  chain  and  with 
each  variation  of  position  make  a  different  compound,  the  amino- 
acids  are  named  according  to  the  position  in  relation  to  the  COOH 
group,  alpha-,  beta-,  gamwa-aminobutyric  or  other  acid  (p.  422). 

Glycin  (CH2(NH2)  .  COOH)  (glycocoll,  amino-acetic  acid} 
occurs  in  animal  secretions,  usually  in  combination  like  uric  acid. 
As  benzoyl-glycin  or  hippuric  acid,  C6H5 .  CO  .  NH  .  CH2  .COOH, 
it  occurs  in  considerable  amounts  in  the  urine  of  herbivora;  and 
to  the  extent  of  about  i  gm.  daily  in  human  urine.  This  amount 
is  much  increased  when  benzoic  acid  and  other  aromatic  sub- 
stances are  taken.  Some  of  the  urea  made  in  the  liver  may  be  an 
oxidation  product  of  glycocoll  reacting  with  NH3.  Thus: 

CH2.NH2.COOH  +  NH3  +  O  =  CO(NH2)2  +  CO2  +  H2O. 

Glycocoll.  Urea. 

Glycin  can  be  prepared  as  hydrochlorid  from  hippuric  or  gly- 
cocholic  acid  by  treatment  with  HC1  (p.  465).  It  contains  an 
amino-group  and  a  carboxyl  group,  and,  therefore,  has 
both  acid  and  basic  properties,  uniting  on  the  one 
hand  with  HC1  to  make  glycin  hydrochlorid  or,  on 
the  other,  with  NaHO  to  form  sodium  glycocollate 
and  water.  It  is  relatively  abundant  as  a  nucleus 
in  the  proteins.  It  crystallizes  in  colorless  prisms, 
soluble  in  water,  giving  a  red  color  with  ferric  chlorid, 
and  with  phenol  and  sodium  hypochlorite  an  intense 
blue. 

Other  amino-acids    of  physiologic   importance  are 
aminopropionic  acid  (alanin),  aminocaproic  acid  (leucins),  amino- 
glutaric  acid  (glutamic),  aminosuccinic   acid  (aspartic),  diamino- 
caproic  acid  (lysin),  diaminovaleric  acid  (ornithin). 

COOH  COOH  COOH  COOH 

CHNH,  CHNH2  CHNH2  CHNH, 

CH3  (CH2)S  (CH2)3  (CH2)2 

CH3  CH2NH2  CH2NH2 

Alanin.  Leucin.  Lysin.  Ornithin. 

Alanin  is  present  free  in  proteins  and  also  in  combination  with 
phenol  to  form  tyrosin,  and  with  indol  to  form  tryptophan. 

Leucin  is  very  abundant  in  all  proteins,  and  is  one  of  the  end- 
products  of  their  digestion.  Having  an  asymmetric  carbon  atom, 
it  has  not  only  the  ordinary  isomers,  but  those  that  are  either 
dextro-  or  levorotatory. 


5oo 


CYCLIC    COMPOUNDS 


Ornithin  is  the  precursor  of  uric  acid  in  its  synthesis  in  birds. 
It  is  present  in  proteins  combined  with  guanidin  to  form  arginin. 

Lysin  is  a  product  of  the  tryptic  digestion  of  fibrin.  When  the 
protein  molecule  is  attacked  by  the  bacteria  of  putrefaction,  CO2 
is  split  off  from  ornithin  to  form  putrescin;  from  lysin  to  form 
cadaverin.  The  acid  character  is  lost  with  the  CO2. 

CH2NH2 .  (CH2)2.  CHNH2 .  COOH  =  CH2NH2 .  (CH2)2 .  CH2NH2  -f  CO2 

Ornithin.  Putrescin. 

CH2NH2(CH2)3  .  CHNH2 .  COOH  =  CH2NH2  .(CH2)3 .  CH2NH2  -f  CO2 

Lysin.  Cadaverin. 

In  this  way  other  ptomains  are  formed  from  other  amino-acids 
by  putrefaction  (p.  519). 

Tyrosin  (1:4  phenolaminopropionic  acid),  is  a  constituent  of 
the  protein  molecule  and  is  produced  by  many  of  its  decom- 
positions. It  has  also  been  prepared  synthetically.  Having  the 
HO  phenol  group,  it  gives  Millon's  reaction.  While  tyrosin  is 
phenol  +  alanin,  it  may  condense  to  indol,  and  indol  +  alanin 
become  tryptophan.  It  may  therefore  be  regarded  as  a  binary 
compound,  like  tryptophan. 

Tryptophan    (skatol  ammo-acetic  acid)  exists    in    the    protein 
molecule  and  is  liberated  by  tryptic  di- 

xv  CH2NH2          gestion.     It   is  the   cause  of  the  Adam- 

/     \ £H  COOH     kiewicz  reaction  given  by  proteins  (a  vio- 
let color  when  treated  with  sulphuric  and 
acetic    acids).     It    is    regarded    as    the 
mother-substance    of   indol,   skatol,  and 
Tryptophan.  skatolcarbonic    acid,  which  are    formed 

from    the    proteins  by    the    bacteria   of 

putrefaction.     In  the  graphic  formula  appended  its  constitution  is 
represented  as  skatol  linked  to  amino-acetic  acid. 

Glucosamin,  CHO  .  CHNH2 .  (CHOH)3CH2OH,  is  an  amin 
in  combination  with  sugar,  existing  as  a  component  of  the 
protein  molecule.  Polymeric  forms  of  an  insoluble  character 
are  called  chitosamins,  and  these  mixed  with  calcium  salts  make 
the  shells  of  crustacean.  Molisch's  reaction  (p.  473),  given  by 
albuminous  substances,  denotes  glucose  in  the  molecule.  The 
large  quantities  of  sugar  excreted  in  diabetes,  even  when  there  is 
no  carbohydrate  in  the  food  or  stored  in  the  liver,  is  due  to  the 
splitting  of  the  glucose  nucleus  from  pure  proteins  by  hydrolysis. 

C6HU05NH2     +      H20     =      C6H1206     +     NH3. 

Serin  and  Cystin. —Amino-acids  may  be  derived  from  oxyacids 
by  substitution  of  NH2  in  a  hydrocarbon  group  or  for  alcoholic 


ALKALOIDS  501 

HO  in  acids  containing  more  than  one  such  group.  Serin  is 
«-amino-/?-oxypropionic  acid  (CH2OH  .  CHNH2  .  COOH),  a  cleav- 
age product  of  silk  fiber  which  is  a  simple  form  of  protein. 
Closely  related  to  serin  is  cystin,  the  compound  which  holds  most 
of  the  sulphur  of  the  protein  molecule.  It  contains  two  molecules 
of  cy stein,  which  is  the  acid  corresponding  to  serin: 

CH2SH  .  CHNH2 .  COOH 

Cystein. 

HOOC  .  CHNH2 .  CH2S  .  SCH2 .  CHNH2 .  COOH 

Cystin. 

Cystin  or  a-diamino-/?-dithiodilactic  acid  is  formed  by  hydrolysis 
of  proteins,  especially  the  keratins  of  hair,  horns,  and  hoof.  When 
produced  in  the  body  by  metabolism  and  not  decomposed,  it  is 
found  in  the  urinary  sediment,  which  may  accrete  to  form  the 
cystin  calculus  (p.  622).  By  feeding  animals  with  cystin  the 
amount  is  increased  of  taurin,  CH2NH2 .  CH2S03H,  a  constit- 
uent of  the  bile  acids  (p.  558).  The  easy  production  of  taurin 
from  cystin  artificially  points  to  the  origin  of  the  bile  constituents 
from  the  cystin  of  the  protein  molecule. 

ALKALOIDS 

Alkaloids  are  nitrogenous  principles  of  alkaline  reaction  and 
basic  properties.  They  are  found  in  plants,  and  in  most  cases 
have  important  physiologic  effects.  A  few  alkaloids,  such  as 
coniin,  nicotin,  spartein,  are  volatile  liquids,  composed  of  carbon, 
hydrogen,  and  nitrogen  only.  More  than  a  hundred  contain  oxy- 
gen in  addition  to  carbon,  hydrogen,  and  nitrogen;  have  a  high 
molecular  weight,  and  are  solid,  crystalline,  and  non-volatile. 

Generally  speaking,  the  alkaloids,  the  constitution  of  which 
has  been  established,  are  tertiary  aromatic  bases,  heterocyclic, 
containing  at  least  one  ring  having  a  nitrogen  atom  in  the  nucleus. 
Exceptions  to  this  are  theobromin  and  caffein,  which  are  purin 
bases  (p.  491). 

Many  of  these  alkaloids  are  known  to  be  derivatives  of  pyrroli- 
din,  pyridin,  piperidin,  quinolin,  or  isoquinolin,  and  contain  the 
pyridin  ring.  It  is  customary  to  regard  them  as  secondary  and 
tertiary  amins,  because  they  have  many  reactions  like  ammonia, 
combining  directly  with  acids  to  form  crystalline  salts  without 
elimination  of  hydrogen  or  water.  Thus: 

2NH3    +     H2S04      =   (NH3)2H2S04  or  (NH4)2SO4. 
2(C17H1903N)     +     H2S04     =     (C17H1903N)2H2S04 

Morphin.  Morphin  sulphate. 


S02 


CYCLIC    COMPOUNDS 


General  properties  of  the  alkaloids  are  as  follows: 
The  liquid  alkaloids  are  volatile,  having  a  disagreeable  odor, 
somewhat  ammoniacal;  the  solid  alkaloids  are  without  odor.  Gen- 
erally speaking,  the  solid  alkaloids  melt  without  decomposition 
when  heated  carefully  above  100°  C.  (212°  F.).  A  much  higher 
temperature  decomposes  them.  Most  of  them  are  white,  crys- 
talline, and  bitter;  and  as  free  bases  are  sparingly  soluble  in 
water,  but  dissolve  readily  in  alcohol,  chloroform,  ether,  petro- 
leum ether,  benzene,  and  amyl  alcohol.  On  the  other  hand,  their 
salts  (chlorids,  sulphates,  nitrates,  acetates,  etc.)  are  mostly  sol- 
uble in  water  or  acidulated  water,  and  in  alcohol;  but,  with  few 
exceptions,  are  insoluble  in  chloroform,  ether,  petroleum  ether, 
benzene,  and  amyl  alcohol. 

In  their  physiologic  action,  as  a  rule,  they  display  great  energy: 
witness  the  convulsive  effects  of  strychnin,  the  coma  induced  by 
morphin,  the  cardiac  depression  caused  by  veratrin  and  aconitin. 
They  are  alkaline,  unite  directly  with  acids  to  form  soluble  salts, 
and  are  liberated  from  this  union  by  the  action  of  alkaline 
hydroxids  and  alkaline  carbonates,  which  precipitate  them  from 
solution.  They  are  also  precipitated  by  lime,  baryta,  and  mag- 
nesia. Other  general  reagents  for  precipitating  alkaloids,  used  for 
their  detection  and  isolation,  are  phospho- 
molybdic  acid,  potassium  mercuric  iodid,  picric 
acid,  tannic  acid,  and  platinum  chlorid.  Dilute 
tannic  acid  and  substances  containing  it,  such 
as  strong  tea  and  the  vegetable  astringents,  are 
used  to  wash  out  the  stomach  as  precipitants  in 
alkaloidal  poisoning. 

Characteristic  color  changes  are  produced  in 
most  alkaloids  by  oxidizing  agents,  such  as 
nitric  acid,  ferric  chlorid,  potassium  dichro- 
mate,  and  sulphuric  acid. 

Extraction  of  Alkaloids.— The  bark,  seeds, 
leaves,  or  roots  of  plants  are  ground  up  and 
macerated  with  dilute  acids,  which  dissolve 
out  the  alkaloids  as  corresponding  salts.  This 
solution,  after  filtration,  is  treated  with  soda 
to  liberate  the  alkaloid  bases.  If  volatile,  the 
FIG.  83.— Separating  funnel,  f^e  alkaloids  may  be  distilled  off;  if  non- 
volatile, the  free  alkaloids  are  usually  nearly 
insoluble,  and  hence  are  precipitated,  to  be  separated  by  filtration. 
To  purify  them  they  must  be  redissolved  in  acids,  again  pre- 
cipitated with  alkali,  and  recrystallized. 

If  this  method  does  not  promise  satisfactory  results,  the  alka- 
line aqueous  extract  is  shaken  out  with  chloroform,  ether,  or  other 


9 


ALKALOIDS  503 

solvent  not  miscible  with  water.  The  solvent  is  then  put  in  a 
separating  junnel  and  allowed  to  form  two  layers,  which  are 
separated  by  permitting  the  heavier  to  flow  through  the  open 
stopcock  into  an  evaporating  dish  (Fig.  83).  The  volatile  liquid 
— chloroform,  ether,  etc. — used  as  a  solvent  is  evaporated  and  the 
alkaloid  is  left  in  the  dish. 

Antidotes  to  Alkaloids  in  General.— The  stomach  should  be 
washed  out  through  a  siphon  tube,  using  freely  water,  strong 
tea,  or  solution  of  tannic  acid,  or  solution  of  10  gr.  of  potas- 
sium permanganate  in  16  fl.  oz.  of  water.  If  the  tube  be  not 
practicable,  vomiting  should  be  induced  by  teaspoonful  doses  of 
mustard  or  2o-grain  doses  of  zinc  sulphate,  or  hypodermic  injec- 
tions of  apomorphin — 5  drops  of  a  2  per  cent,  solution.  After 
evacuation  of  the  stomach  and  administration  of  10  grains  potas- 
sium permanganate  in  a  tumbler  of  water,  the  dangerous  symp- 
toms are  combated  with  remedies  which  are  physiologic  antago- 
nists— that  is,  stimulants,  such  as  whisky  and  ammonia;  artificial 
respiration,  etc. 

Detection  of  Alkaloids  in  Animal  Mixtures.— No  oper- 
ation of  the  toxicologist  demands  so  much  expert  skill  as  that  of 
separating  from  organic  matter  an  alkaloid  in  a  state  so  pure  as 
to  justify  the  analyst  in  swearing  to  its  identity.  The  technical 
problem  is  rendered  more  complex  by  the  presence,  in  decaying 
animal  substances,  of  cadaveric  alkaloids  or  ptomains,  behaving 
chemically,  if  not  physiologically,  like  the  vegetable  alkaloids. 
(For  the  details  of  this  procedure  see  p.  521.) 

Classification  of  Important  Alkaloids.— The  constitu- 
tion of  many  alkaloids  is  as  yet  undetermined;  some  of  them, 
however,  are  known  to  be  derivatives  of  or  to  contain  the  nuclei 
of  the  heterocyclic  compounds  pyrrolidin,  piperidin  (p.  484), 
pyridin,  quinolin,  isoquinolin,  and  phenanthrene.  According  to 
these  complex  nuclei  found  in  them,  the  commonly  used  alkaloids 
named  below  are  classified  as  derivatives  of— 

1.  Pyrrolidin. — The  poisonous  hygrins  of  coca. 

2.  Pyridin. — Pilocarpin  of  jaborandi. 

3.  Piperide'in. — Arecolin  of  betelnut,  pelletierin  of  jaborandi. 

4.  Piperidin. — Coniin  of  hemlock,  piperin  of  pepper. 

5.  Pyrrolidin-pyridin. — Nicotin  of  tobacco. 

6.  Pyrrolidin-piperidin. — The  tropan  alkaloids,  such  as  atropin 

of  nightshade,  hyoscyamin  of  henbane  cocain,  and  ecgonin 
of  coca. 

7.  Quinolin. — The    cinchona    alkaloids;    also    strychnin    and 

brucin. 

8.  Isoquinolin. — Narcotin,  narcein,  papaverin  of  opium,  and 

hydrastin  of  yellow  root. 


504  CYCLIC    COMPOUNDS 

9.  Phenanthrene. — Morphin  and  codein  of  opium. 
10.   Of    Unknown    Constitution.— -Veratrin,     aconitin,    ergotin, 
gelsemin,  physostigmin,  and  many  others. 

PYRIDIN   ALKALOIDS 

Pilocarpin,  CUH16N2O2,  is  an  alkaloid  found  in  jaborandi 
(pilocarpus).  Its  structure  is  not  perfectly  known,  but  its  reactions 
are  those  of  a  compound  containing  the  pyridin  ring  with  the 
group  C6H12NO2  linked  in  the  ft  position.  Like  atropin  and 
cocain,  it  is  an  ester  decomposed  by  alkalis.  It  is  crystalline, 
colorless,  soluble,  and  alkaline.  The  official  salts  are  the  hydro- 
chlorid  and  nitrate,  used  as  a  diaphoretic  and  miotic.  Dose:  o.i  to 
0.5  gr.  (0.005-0.03  gm.)  hypodermically.  If  instilled  into  the  eye 
to  contract  the  pupil,  i  or  2  drops  of  a  i  per  cent,  solution. 

Incompatibles:  mercuric  chlorid,  silver  nitrate,  tannin,  iodids, 
atropin. 

Toxicology. — The  symptoms  produced  by  pilocarpin  in  full 
doses  are  copious  sweating,  salivation,  increase  of  milk  and  other 
secretions,  contracted  pupils,  diminished  blood-pressure,  lower 
temperature,  and  prostration. 

Treatment. — After  evacuation  of  the  stomach  and  washing  out 
with  solutions  of  tannin,  the  physiologic  antagonist  is  given — 
atropin,  gir  gr->  hypodermically.  Whisky  and  ammonia  are  use- 
ful as  stimulants. 

PIPERIDIN   ALKALOIDS 

Coniin,  C8H17N,  is  prepared  from  the  fruit  of  the  spotted 
hemlock  by  distillation  with  soda.  At  first  it  is  a  colorless  oil, 
but  later  changes  to  brown.  It  has  an  acrid  taste,  a  penetrating 
mousy  odor,  and  is  soluble  in  water.  It  is  strongly  basic,  form- 
ing soluble  salts.  It  is  one  of  the  simplest  alkaloids  in  constitu- 
tion, and  the  first  instance  of  one  prepared  synthetically.  It  is 
a-propylpiperidin,  as  is  shown  in  these  formulas: 

CH  CH2  CH2 

H2G/    \.CH2  H2C/  \:H2 

H2cl  JcH2  H2cl          JcHC3Hr 

NH  NH 

Piperidin.  Coniin. 

Toxicology. — Symptoms. — Coniin  is  exceedingly  poisonous  to 
the  motor  centers,  a  few  drops  sufficing  to  paralyze  the  muscles 
of  respiration  in  from  one  to  three  hours.  It  produces  great 
prostration,  headache,  weakness  or  paralysis  of  the  extremities, 


NICOTIN  505 

dilated  pupils;  the  intellect  remains  clear  until  death  occurs  by 
failure  of  respiration.  Two  grains  would  probably  prove  fatal. 

Treatment. — The  stomach  should  be  washed  out  after  giving 
tannic  acid  or  vegetable  astringents.  The  indications  are  for 
strong  coffee,  whisky,  and  strychnin  hypodermically.  Artificial 
respiration  may  be  necessary. 

Tests. — (i)  The  odor  is  that  of  a  mouse's  nest. 

(2)  Touched  with  alloxan,  coniin  develops  a  purple-red  color 
and  white  crystals.     The  crystals,   touched  with  potassium  hy- 
droxid,  evolve  the  odor  of  mice  and  turn  purple. 

(3)  Warmed  with  potassium  dichromate  and  sulphuric  acid, 
coniin  yields  butyric  acid,  detected  by  its  odor. 

(4)  Coniin  placed  on  the  tongue  of  a  small  animal  causes  un- 
steady gait,   paralysis,   convulsions,   tremor,    dilated  pupils,   and 
death  in  a  few  minutes. 


PYRROLIDIN-PYRIDIN   ALKALOIDS 

Nicotin,  C10H14N2,  is  prepared  from  the  leaves  of  the  tobacco 
plant  by  distilling  the  aqueous  extract  with  milk  of  lime.  Further 
steps  are  necessary  to  render  it  pure. 

It  is  a  colorless  oil,  turning  brown  on  exposure.  It  has  a  burning 
taste,  a  pungent,  disagreeable  odor,  like  that  of  an  old  pipe,  and 
is  soluble  in  water.  It  is  a  strong  diacid  base,  forming  salts 
which  crystallize.  By  oxidation  with  chromic  acid  it  yields 
nicotinic  acid  (pyridin-y5-carboxylic  acid),  C5H4N  .  CO  OH,  proving 
it  to  be  a  pyridin  derivative  with  the  pyridin  nucleus: 


Toxicology. — Nicotin  is  fatally  poisonous  in  doses  of  2  or  3 
drops  of  the  alkaloid,  taken  into  the  stomach.  Four  drops  will 
kill  a  dog  within  five  minutes.  An  infusion  or  decoction  of  tobacco 
leaves  is  the  common  form  by  which  nicotin  poisoning  is  induced. 
It  may  be  swallowed  or  given  by  enema,  intentionally  or  by  mistake. 

The  symptoms  are  nausea,  vomiting,  muscular  relaxation,  gid- 
diness, numbness,  dilated  pupils,  diuresis,  collapse  with  cold, 
damp  skin,  small  and  thready  pulse,  and  death  by  heart  failure. 
When  the  dose  is  very  large,  unconsciousness  occurs  immediately; 
and  after  a  few  respirations  death  follows  within  five  minutes. 


506  CYCLIC    COMPOUNDS 

Treatment.  —  If  time  permits  and  there  has  been  no  free  vomiting, 
the  stomach  must  be  washed  out  with  abundance  of  warm  water 
or  tea.  The  patient  is  kept  recumbent  and  warm,  while  stimulation 
is  practised  with  whisky  or  by  hypodermic  injections  of  strychnin 
nitrate,  fa  gr. 

Detection.  —  Its  reactions  are  not  very  characteristic.  With 
nitric  acid  it  gives  an  orange  color;  with  hydrochloric  acid,  a  violet. 
Dissolved  in  ether  and  mixed  with  an  ethereal  solution  of  iodin, 
it  yields  an  oily  resin  of  brownish  color,  which  in  time  forms  crystals. 
Its  presence  may  be  detected  by  the  familiar  odor  of  stale  tobacco. 

PYRROLIDIN-PIPERIDIN   ALKALOIDS 

Atropin  (C17H23NO3)  (Atropia,  Atropina).  —  From  the  plants  of 
the  Solanacese  —  belladonna,  stramonium,  hyoscyamus,  scopola, 
and  duboisia  —  are  obtained  four  important  alkaloids  —  atropin  or 
daturin,  belladonin,  hyoscyamin,  and  hyoscin  or  scopolamin. 

The  deadly  nightshade  (Atropa  belladonna}  contains  two  alkaloids 
isomeric  and  much  alike  in  properties:  hyoscin  and  hyoscyamin. 
The  latter,  when  treated  with  potash,  changes  to  atropin  by  re- 
arrangement of  its  atoms.  All  of  these  and  the  coca  alkaloid, 
cocain,  also  contain  a  methylated  pyrrole  ring  (p.  483)  in  com- 
bination with  a  piperidin  ring  (p.  484). 

Properties.  —  Atropin  forms  glistening  prismatic  needles,  odor- 
less, bitter,  almost  insoluble  in  water,  but  readily  soluble  in  chloro- 
form, alcohol,  and  ether.  It  is  strongly  basic,  neutralizing  acids, 
forming  salts,  of  which  the  sulphate  is  characterized  by  its  ready 
solubility.  Atropince  sulphas,  (C17H33NO3)2H2SO4,  is  either  crys- 
talline or  amorphous,  and  is  used  in  medicine  instead  of  the  base. 

When  atropin  or  hyoscyamin  is  boiled  in  baryta  water,  it  under- 
goes hydrolysis,  breaking  up  into  tropic  acid  and  the  base,  tropin: 


C17H23N03    +    H20    =    C6H5CH<2          +    C8H15NO 

Atropin.  Tropic  acid.  Tropin. 

This  is  a  reversible  reaction,  as  shown  when,  by  synthetic 
methods,  the  components,  tropic  acid  and  tropin,  are  first  built 
up  and  then  readily  combine  to  form  atropin  and  water. 

Homatropin  hydrobromid,  C16H21NO3  .  HBr,  is  the  salt  of  an 
alkaloid  obtained  by  the  condensation  of  tropin  and  mandelic 
acid.  It  is  a  white,  colorless,  odorless,  water-soluble  powder,  used 
as  a  rapid  and  transient  mydriatic.  It  gives  Vitali's  test. 

Physiologic  Effects.  —  Atropin  is  a  depressant  of  the  cerebro- 
spinal  nervous  system,  but  a  stimulant  to  the  sympathetic.  It 
dilates  the  pupils,  paralyzing  ocular  accommodation;  increases  the 


COCAIN  507 

blood-pressure  and  the  force  and  frequency  of  cardiac  action; 
deepens  the  respiration;  flushes  the  face;  diminishes  the  secre- 
tion of  sweat,  saliva,  milk,  and  bronchial  mucus.  It  is  used  as 
an  antispasmodic,  an  anodyne,  and  an  antidote  to  physostigma 
and  opium.  Dose:  -^^  to  ^  gr. 

A  i  per  cent,  solution  is  dropped  into  the  eye  to  paralyze 
accommodation  and  dilate  the  pupil  for  eye-testing,  and  to  treat 
iritis. 

Toxicology. — An  overdose  causes  delirium,  very  rapid  pulse, 
dry  throat,  thirst,  flushed  skin  like  a  scarlatinal  rash,  pupils  widely 
dilated,  vision  impaired,  giddiness,  muscular  incob'rdination, 
retention  of  urine.  In  the  later  stage  coma  succeeds  the  noisy 
delirium,  and  the  respiration  becomes  slow  and  shallow,  death 
ending  the  scene  with  cardiac  or  respiratory  paralysis. 

Treatment. — After  washing  out  the  stomach  with  a  solution  of 
tannic  acid  or  evacuation  by  an  emetic,  hypodermic  injection  of 
strychnin  is  given  to  stimulate  respiration;  of  morphin  cautiously 
to  allay  the  cerebral  excitement  of  the  first  stage.  In  case  of 
collapse  heat  is  applied  to  the  feet  and  epigastrium,  and  tea  or 
whisky  administered. 

Postmortem  appearances  are  in  no  way  characteristic. 

Tests. — Vitali's. — A  trace  of  atropin  or  its  salts,  moistened 
with  fuming  nitric  acid  and  dried  on  a  water-bath,  yields  a  yellow 
residue  (that  of  morphin  would  be  red),  which,  moistened  with 
alcoholic  potash,  gives  a  violet  solution,  changing  to  red. 

A  few  drops  of  sulphuric  acid  dissolve  a  fragment  of  atropin 
without  change  of  color;  a  crystal  of  potassium  dichromate  added 
will,  after  a  while,  turn  the  mixture  green,  and  on  warming  with  a 
little  water  develop  an  odor  of  orange  blossoms. 

Physiologic. — Dropped  into  the  eye  of  a  cat,  a  solution  of 
atropin  dilates  the  pupil  widely. 

Cocain  (C17H21NO4). — Of  the  several  alkaloids  of  Erythroxylon 
coca  this  is  the  only  one  of  importance  in  medicine.  It  is  obtained 
in  colorless  prismatic  crystals,  which  fuse  at  98°  C.  (208.4°  F.) 
and  are  sparingly  soluble  in  water.  It  is  bitter  and  later  benumb- 
ing to  the  sense  of  taste.  Chemically,  it  resembles  atropin,  being 
strongly  alkaline  and  forming  salts,  of  which  the  hydrochlorid  is 
used  extensively  in  medicine.  This  is  soluble  in  one-half  part  of 
water,  and  also  in  alcohol,  glycerin,  and  chloroform.  Heat  should 
not  be  used  in  preparing  its  solutions.  Boiled  with  water,  it  is 
hydrolyzed  into  benzoyl-ecgonin,  and  if  acids  or  alkalis  be  present, 
further  hydrolysis  occurs,  with  formation  of  ecgonin,  benzoic  acid, 
and  methyl  alcohol: 

C17H21N04  +  2H20  =  C9H15N03  +  C6H5 .  COOH  +  CH3OH. 

Cocain.  Ecgonin.  Benzoic  acid. 


508  CYCLIC   COMPOUNDS 

This  reaction  shows  that  cocain  is  the  methyl  ester  of  benzoyl 
ecgonin.  Locally  to  mucous  membranes,  or  hypodermically, 
cocain  acts  as  an  anesthetic,  rendering  minor  surgical  operations 
painless.  It  is  given  internally  to  relieve  nausea.  Dose:  £  to  J 
gr.  (0.015-0.03  gm.).  For  local  application  a  solution  is  used,  2  to 
10  per  cent.  Its  systemic  effect  is  stimulant  and  diuretic. 

Toxicology. — In  overdoses  cocain  causes  nausea,  vomiting, 
vertigo,  muscular  prostration,  and  heart  failure.  Both  pulse  and 
breathing  are  much  disordered.  At  times  there  is  blindness, 
aphonia,  or  convulsions. 

The  habitual  use  of  cocain,  or  cocainism,  causes  deterioration 
of  the  moral  sense  and  varied  nervous  phenomena. 

Treatment. — In  treating  cocain  poisoning,  after  evacuation  of 
the  stomach  the  chemical  antidotes  are  those  used  for  all  alka- 
loids: tannin  and  vegetable  astringents;  iodin,  i  gr.,  and  potas- 
sium iodid,  10  gr.,  dissolved  in  water.  The  physiologic  antago- 
nists are  digitalis  and  inhalations  of  amyl  nitrite  for  the  syncope; 
caffein  and  whisky  as  stimulants;  oxygen  for  cyanosis;  morphin 
for  nervous  excitement. 

Detection. — (i)  Iodin  dissolved  in  potassium  iodid  solution 
precipitates  cocain  red. 

(2)  Picric  acid  gives  a  yellow,  powdery  precipitate   when  the 
cocain  is  in  concentrated  solution. 

(3)  The  suspected  solution  is  boiled  for  a  few  minutes  with  sul- 
phuric acid,  neutralized  with  potassium  hydroxid,  and  then  treated 
with  a  few  drops  of  ferric  chlorid.     Ferric  benzoate  is  precipitated 
brownish  yellow. 

Physiologic  Test. — A  neutral  solution  of  the  cocain  hydrochlorid 
applied,  several  drops  in  succession,  to  tongue  or  lip  causes  numbness 
and  insensibility,  lasting  a  few  minutes  only.  The  same  effect  is 
obtained  on  the  eye  with  some  transient  dilatation  of  the  pupil. 

Eucain  is  an  artificial  alkaloid,  employed  locally  as  a  substitute 
for  cocain,  because  safer.  There  are  two  forms,  alpha  and  beta. 
Alpha-eucain,  C19H27NO4HC1,  is  a  benzoyl-methyl-tetra-oxy-piperidin- 
carboxylic-methyl-ester.  Beta-eucain,  C17H21NO2HC1,  is  a  benzoyl- 
vinyl-diaceton-alkamin.  A  white,  neutral,  water-soluble  powder,  less 
toxic  on  the  heart  than  cocain  or  alpha-eucain,  and  sterilizable  without 
decomposition  by  boiling.  Used  in  2  per  cent,  solution. 

QUINOLIN    ALKALOIDS 

Quinin  (C20H24N2O2).— This  and  several  other  allied  alkaloids 
(cinchonin,  quinidin,  cinchonidiri)  occur  in  cinchona  bark,  com- 
bined with  quinic  and  quinotannic  acids.  The  best  varieties  of 
calisaya  contain  4  per  cent,  of  ether-soluble  alkaloids,  of  which  3 
per  cent,  is  quinin.  The  crystalline  form  contains  3  molecules  of 


CINCHONIN  509 

water  and  is  with  difficulty  soluble  in  water.  It  is  a  feeble  diacid 
base,  forming  hydrogen  salts  with  sulphuric  acid — the  sulphate, 
(C20H24N2O2)2H2SO4  +  7H2O,  and  the  bisulphate,  C20H24N2O2 . - 
H2SO4  +  7H2O — both  of  which  crystallize  in  silky  needles,  light, 
bitter,  and  soluble.  The  solutions  are  fluorescent,  with  a  pale-blue 
color.  The  bisulphate  is  by  far  the  more  soluble.  The  sulphate 
contains  75  per  cent,  anhydrous  quinin  and  requires  720  parts 
of  water  or  86  of  alcohol  to  dissolve  it;  the  bisulphate  has  60  per 
cent,  anhydrous  quinin  and  requires  for  solution  only  9  parts 
of  water  or  18  of  alcohol;  the  salicylate  has  70  per  cent,  anhydrous 
quinin  and  dissolves  in  77  parts  of  water  or  n  of  alcohol. 

It  has  been  established  that  quinin  is  a  methoxycinchonin  and 
a  derivative  of  quinolin,  because  with  oxidizing  agents  it  yields 
quininic  acid  (methoxyquinolin-r-carboxylic  acid).  Both  alkaloids 
contain  a  group,  C10H15(OH)N,  the  structure  of  which  is  undeter- 
mined. Their  constitution,  so  far  as  known,  is  represented  by  the 
following  formulas,  in  which  it  is  shown  that  quinin  differs  from 
cinchonin  by  the  substitution  of  methoxyl,  CH3O  for  H: 


CH 


Quinin. 


In  doses  of  2  to  5  gr.  (0.1-0.3  gm-)  quinin  acts  as  a  stimu- 
lant, especially  to  the  nervous  system;  in  doses  of  5  to  30  gr.  (0.3- 
2  gm.)  it  is  an  antiperiodic  for  malarial  fevers;  in  doses  of  10  gr. 
(0.6  gm.),  an  antipyretic;  in  doses  of  i  to  2  gr.  (0.06-0.13  gm.), 
a  general  tonic. 

In  overdoses  it  produces  quinin  fever,  with  erythema,  ringing 
in  the  ears,  hemorrhage  into  the  labyrinth,  with  deafness,  tran- 
sient blindness,  destruction  of  the  blood-corpuscles,  and  even 
respiratory  failure. 

Tests.— (i)  A  salt  of  quinin  with  chlorin  or  bromin  water 
treated  with  excess  of  ammonium  hydroxid  gives  a  characteristic 
emerald-green  color,  due  to  thalleioquin. 

(2)  Dilute  solutions  of  quinin  salts  acidulated  with  sulphuric 
acid  give  a  beautiful  light  blue  fluorescence.  A  red  color  with 
concentrated  sulphuric  acid  shows  that  other  substances  are  present. 

Cinchonin,  C19H22N2O,  is  found  with  quinin  in  almost  all  the 
cinchona  barks.  It  is  a  white,  bitter,  crystalline  alkaloid,  resem- 
bling quinin  in  ordinary  properties,  though  medicinally  much  less 
effective.  It  is  a  quinolin  derivative,  as  stated  above. 


510 


CYCLIC    COMPOUNDS 


The  doses  of  the  cinchonin  salts  are  about  double  those  of  the 
quinin  salts. 

Tests. — (i)  A  salt  of  cinchonin  with  chlorin  or  bromin  water 
yields  a  yellowish  white  precipitate  insoluble  in  ammonia. 

(2)  A  neutral  solution  of  cinchonin  gives  with  potassium  ferro- 
cyanid  a  white  precipitate  soluble  in  excess.  This  solution  in 
excess,  treated  with  an  acid,  yields  a  golden  yellow  precipitate. 

Strychnin  (C2iH22N2O2). — This  alkaloid,  accompanied  by 
brucin,  is  contained  in  the  seeds  of  Strychnos  nux  vomica  and  dif- 
ferent plants  of  the  same  genus.  They  are  usually  extracted 
from  nux  vomica,  which  contains  from  3  to  4  per  cent,  of  alka- 
loids. 

Properties. — Strychnin  crystallizes  in  white,  rhombic  prisms, 
without  odor,  but  with  an  intensely  bitter  taste.  It  is  very  spar- 
ingly soluble  in  water,  but  sufficiently  so  to  impart  a  bitter  taste 
even  when  the  amount  is  only  i  :  700,000.  It  is  more  soluble  in 
acidulated  water  and  in  chloroform. 

Both  strychnin  and  brucin  are  strong  monacid  bases,  forming 
salts,  many  of  which  are  soluble  in  water.  An  official  salt  is  the 
sulphate,  (C21H22N2O2)2H2SO4,  5H2O.  This  crystallizes  in  rectan- 
gular prisms,  is  soluble  in  water  and  alcohol,  and  is  intensely  bitter. 

While  little  is  known  of  the  constitution  of  strychnin,  it  is  con- 
sidered to  be  a  tertiary  base,  and  as  quinolin  is  a  product  of  its 
distillation  with  potash,  it  is  probably  a  derivative  of  quinolin. 

Medical  Uses. — Strychnin  is  a  bitter  tonic,  stimulating  reflex 
activity,  and  in  large  doses  causing  tetanic  convulsions.  It  aug- 
ments the  force  of  the  heart's  action,  raises  blood-pressure,  in- 
creases the  depth  and  frequency  of  respiration.  Dose  of  strychnin 
or  its  salts:  -^  to  ^  gr.  (0.001-0.005  gm-)- 

Toxicology. — Poisonous  Symptoms. — The  most  marked  effects 
are  the  convulsions,  which  at  first  are  clonic  (intermittent),  but  as 
the  intervals  become  shorter  and  the  paroxysms  longer  eventu- 
ally become  tonic  (tetanic).  The  mouth  is  drawn  in  the  risus 
sardonicus,  and  the  body  usually  bent  back  so  as  to  rest  on  the 
heels  and  occiput  (opisthotonos).  The  spasms  of  the  diaphragm, 
drawing  upon  the  ensiform  cartilage,  cause  epigastric  pains.  The 
contractions  of  the  respiratory  muscles  produce  a  sense  of  suffo- 
cation which  may  end  in  asphyxia.  The  mind  remains  clear  to 
the  last;  the  pupils  contract  during  the  paroxysm.  The  reflex 
excitability  is  so  great  that  a  loud  noise  or  the  touch  of  a  medi- 
cine glass  to  the  lips  brings  on  a  convulsion.  Vomiting  is  readily 
induced  and  persists  when  once  excited. 

Should  a  paroxysm  last  too  long,  asphyxia  may  prove  fatal. 
Many  repetitions  of  the  painful  spasms  may  cause  death  in  the 
intervals,  as  the  result  of  exhaustion. 


BRUCIN  511 

Fatal  Period. — As  a  rule,  the  symptoms  appear  in  less  than 
twenty  minutes  after  administration,  but  may  be  delayed  for  an 
hour.  Usually,  if  the  dose  be  very  large,  death  occurs  within  two 
hours,  sometimes  in  a  few  minutes.  There  are  cases  of  death 
occurring  as  long  as  six  hours  after  taking  the  poison. 

Fatal  Dose. — The  smallest  amount  known  to  have  caused  death 
is  J  gr.  On  the  other  hand,  a  dose  of  20  gr.  has  been  taken  and 
did  not  prove  fatal. 

Treatment. — After  the  inhalation  of  chloroform  to  control  the 
spasms,  the  stomach  tube  may  be  introduced,  and  protected  by  a 
wooden  wedge  between  the  teeth.  Warm  water  containing  potas- 
sium permanganate,  4  gr.  in  n  fl.  oz.,  should  be  used  freely  to 
wash  out  the  stomach.  In  the  absence  of  a  tube,  emetics  of 
mustard  or  zinc  sulphate  should  be  given,  or  hypodermics  of  apo- 
morphin.  Chloral  hydrate  in  3o-grain  doses  should  be  given  by 
the  rectum,  and  retention  insured  by  giving  chloroform  or  amyl 
nitrite  inhalation.  Gentle  narcosis  and  perfect  quiet  are  desirable. 

Detection. — (i)  If  strychnin  be  present  in  amounts  to  be  recog- 
nized by  chemical  tests,  a  bitter  taste  will  be  perceptible.  If  this 
taste  be  absent,  no  other  tests  will  show  strychnin. 

(2)  A  small  quantity  on  a  white  dish  dissolves  in  a  little  con- 
centrated sulphuric  acid  without  color. 

(3)  A  small  portion  of  powdered  potassium  dichromate  dusted 
over  the   above   solution  in   sulphuric   acid  produces   a  transient 
blue,   then   an   intense   violet   color,    which   gradually   changes  to 
bright  red,  then  to  rose  pink,  and  lastly  to  yellow.     This  reaction 
is  sufficiently  delicate  to  reveal  i  :  50,000. 

Fallacy. — A  mixture  of  morphin  or  heroin  with  10  per  cent,  of 
hydrastin  gives  with  this  test  a  similar  play  of  colors. 

(4)  Sonnenschein's  reagent,   cerosoceric  oxid,  is  first  made  by 
heating  cerium  oxalate  to  redness  and  then  dissolving  it  in  30  parts 
of  sulphuric  acid.     A  fragment  of  strychnin  stirred  into  a  drop 
of  this  solution  causes  a  play  of  colors — blue,  violet,  and  red. 

Physiologic  Test. — When  a  small  frog  is  immersed  in  a  solution 
of  strychnin,  or  when  a  hypodermic  injection  of  it  is  given  to  frogs 
or  white  mice  two  weeks  old,  muscular  twitchings  and  convulsions 
are  produced,  ending  in  tetanic  rigidity  and  death. 

Brucin  (C23H26N2O4, 4H2O).— This  alkaloid  is  found  with 
strychnin.  It  is  obtained  in  colorless  prismatic  crystals,  slightly 
more  soluble  in  water  and  alcohol  than  strychnin,  readily  soluble 
in  chloroform  and  amyl  alcohol.  It  resembles  strychnin  in  being 
intensely  bitter,  a  strong  monacid  base,  and  a  spinant  poison, 
though  its  physiologic  energy  is  only  one  twenty-fourth  of  that  of 
strychnin.  It  is  a  tertiary  base,  forming  salts  which  are  soluble 
and  crystalline. 


512 


CYCLIC    COMPOUNDS 


Medical  Uses. — It  is  a  bitter  tonic.  Dose:  0.08  to  0.5  gr. 
(0.005-0.03  gm.). 

Tests. — (i)  A  solution  of  brucin  treated  with  nitric  acid  gives 
a  solution  having  a  deep  red  color,  which  when  warmed  turns 
yellow.  If  a  reducing  agent  be  added,  such  as  a  crystal  of  stan- 
nous  chlorid  or  of  sodium  thiosulphate,  the  color  changes  to  an 
intense  violet. 

(2)  A  concentrated  brucin  solution  treated  cautiously  with 
drops  of  chlorin  water  gives  a  bright  red  color,  changing  to  violet. 
Excess  of  chlorin  water  decolorizes  it,  and  ammonia  turns  it  brown. 

PHENANTHRENE   ALKALOIDS 

When  the  unripe  heads  of  certain  kinds  of  poppy  (Papaver 
somnijerum)  are  incised,  a  juice  exudes  and  dries  to  a  brown 
paste,  called  opium.  Opium  contains  at  least  seventeen  different 
alkaloids,  of  which  the  most  important  is  morphin.  Others  worthy 
of  mention  are  codein,  narcotin,  thebain,  and  papaverin.  They 
all  exist  in  combination,  partly  with  sulphuric  acid,  but  mainly 
with  meconic  acid.  This  is  a  hydroxydicarboxylic  acid  of  the  fatty 
series,  having  the  formula  C5HO2(OH)(COOH)2.  It  can  be  ob- 
tained as  crystals,  and  is  detected  by  the  intense  dark-red  color 
given  with  neutral  ferric  chlorid,  the  color  persisting  after  treatment 
with  mercuric  chlorid  or  boiling  with  hydrochloric  acid. 

Opium  occurs  in  masses  or  powder  of  a  chestnut  brown  color, 
a  narcotic  odor,  and  a  bitter  taste.  The  crude  drug  should  contain 
not  less  than  9  per  cent,  of  morphin,  and  dry  powdered  opium  not 
less  than  12  per  cent.  Morphin  is  the  active  narcotic  principle 
in  all  the  official  preparations  of  opium  and  in  various  proprietary 
anodynes  and  carminatives,  such  as  Mrs.  Winslow's,  Dalby's, 
Battle's,  also  in  nepenthe,  chlorodyn,  and  most  opium  cures. 

The  dose  of  powdered  opium  of  standard  morphin  strength  re- 
quired to  narcotize  is  5.6  times  as  much  as  that  of  morphin  sulphate. 

Morphin  (C17H19NO3).— The  free  base  takes  i  molecule  of  water 
of  crystallization  to  form  colorless  prisms.  Slightly  soluble  in 
water  and  cold  alcohol,  it  dissolves  easily  in  potash  and  soda,  to 
be  precipitated  again  on  the  addition  of  an  acid.  This  behavior 
is  due  to  the  presence  of  phenolic  hydroxyl,  which  group  is  the 
cause  of  the  blue  color  reaction  with  ferric  chlorid.  It  contains 
another  hydroxyl  group  which  is  alcoholic.  Morphin  boiled  with 
zinc  dust  yields  pyridin,  quinolin,  phenanthrene,  and  other  sub- 
stances showing  it  to  be  a  polynucleated  compound.  When  one 
of  its  hydrogen  atoms  is  replaced  by  methyl,  the  product  is  codein. 
Codein  is  soluble  in  water,  alcohol,  and  ether,  and  readily  forms 
salts  with  acids.  As  a  hypnotic  the  dose  is  twice  as  large  as  that 
of  morphin,  being  J-i  gr.  (0.03-0.13  gm.). 


MORPHIN  513 

Dionin  is  dimethyl  morphin  hydrochlorid,  and  like  codein. 

Heroin,  used  as  a  substitute  for  codein,  is  diacetyl  morphin, 
or  the  acetic  ester  of  that  alkaloid.  Used  for  coughs,  dose:  ^-\  gr. 
(o.oi  gin.). 

Apomorphin,  C17H17NO2,  is  prepared  by  heating  morphin  with 
hydrochloric  acid  in  a  sealed  tube  to  140°  C.  (252°  F.)  for  three 
hours.  The  chlorid  occurs  in  colorless  crystals  turning  greenish 
by  exposure  to  light.  Soluble  in  7  parts  of  water,  it  is  used  hypo- 
dermically  as  an  emetic  in  five  drops  of  a  2  per  cent,  solution. 

Morphin  is  a  monacid  base,  forming  well-defined  salts  with 
the  acids.  While  the  hydrochlorate  and  acetate  are  official,  the 
salt  commonly  used  is  the  sulphate,  (C17H19NO3)2H2SO4,  5H2O. 

Morphin  sulphate  is  dispensed  in  white,  snowy  needles,  odorless 
and  bitter.  It  is  readily  soluble  in  water  and  moderately  so  in 
alcohol,  giving  a  neutral  reaction.  Dose:  J  to  J  gr.  (0.008-0.03 
gm.).  One-sixth  of  a  grain  is  equal  in  anodyne  and  narcotic  prop- 
erties to  i  gr.  of  opium.  Cases  of  intense  pain  usually  require 
several  doses  of  J  gr.  hypodermically. 

Toxicology. — Symptoms. — The  poisonous  effects  of  a  dose  by 
the  mouth  begin  to  show  in  about  twenty  minutes.  A  hypoder- 
mic dose  causes  drowsiness  earlier  and  some  relief  of  pain  in  five 
minutes.  There  is  an  initial  stage  of  exhilaration  with  strength- 
ening of  the  pulse.  This  soon  ends  in  giddiness,  languor,  som- 
nolency, nausea,  itching  of  the  skin,  and  slow,  full  pulse.  The 
pupils  are  contracted  to  the  size  of  a  pin's  head,  and  are  not 
influenced  by  light  and  darkness.  There  are  shallow  and  stertor- 
ous respirations,  with  peculiar  death-like  pauses  lasting  half  a 
minute,  alternating  with  periods  of  about  thirty  irregular  respira- 
tions. 

The  breathing  may  not  have  this  rhythmic  character,  but  may 
pass  gradually  and  calmly  to  feeble  and  slow  breathing,  asphyxia, 
and  death.  As  the  respiration  is  disturbed,  the  surface  grows  blue, 
cold,  and  damp;  the  urine  is  retained.  As  death  approaches,  the 
coma  is  profound,  the  pulse  becomes  weak,  and  the  pupils  may 
•dilate. 

Anomalous  cases  are  reported  in  which  convulsions  occur;  spon- 
taneous vomiting  and  diarrhea  have  been  known  to  eject  the  poison 
and  save  the  patient.  Very  rarely  the  pupils  have  not  been  con- 
tracted. Relapse  into  coma  and  death  has  happened  even  after 
the  patient  has  recovered  consciousness. 

'Fatal  Period. — Death  has  occurred  in  forty-five  minutes,  and, 
on  the  other  hand,  has  supervened  after  the  lapse  of  four  days. 
In  most  of  the  fatal  cases  life  is  prolonged  from  six  to  twelve  hours. 
If  breathing  can  be  kept  up  for  forty-eight  hours,  recovery  is  highly 
probable. 

33 


5*4 


CYCLIC    COMPOUNDS 


Fatal  Dose. — Most  persons  not  habituated  to  opium  would  die 
after  5  to  10  gr.  of  opium  or  i  to  2  gr.  of  morphin.  There  are  per- 
sons highly  susceptible  who  are  poisoned  by  doses  of  less  than  i 
gr.  of  morphin;  while,  on  the  other  hand,  there  are  those  habituated 
to  the  use  of  opium  who  not  only  survive  enormous  amounts,  but 
take  daily  doses  ten  times  the  fatal  quantity  without  apparent 
injury. 

Treatment. — The  stomach  should  be  washed  out  with  the  siphon 
tube,  using  water  containing  potassium  permanganate,  10  gr.  to 
the  tumblerful.  This  agent  promotes  morphin  oxidation.  If  this 
be  not  procurable,  the  washing  may  be  done  with  infusions  of  tea 
or  tannic  acid,  or  mixtures  of  powdered  animal  charcoal  and  water. 
Emetics  of  mustard  may  be  given  in  i  or  2  doses  of  a  teaspoonful 
each,  or  zinc  sulphate,  20  to  30  gr.  A  prompt  emetic  given 
hypodermically  is  apomorphin,  5  to  10  min.  of  a  2  per  cent,  solution. 
When  the  permanganate  is  given  subcutaneously,  it  forms  with 
the  serum  of  the  blood  an  albumin  manganic  oxid  which  has  the 
power  of  decomposing  the  morphin.  Solutions  of  0.5  per  cent, 
strength  (i  gr.  in  2  fl.  oz.)  may  be  injected  in  amounts  of  i  to  6 
fl.  dr.  at  two  or  three  points. 

The  symptoms  to  be  combated  are  failure  of  respiration  at  first, 
and  later  on  the  weakened  action  of  the  heart.  Somnolency  itself 
is  not  important  if  the  patient's  breathing  be  sustained.  In  time 
the  poison  will  be  oxidized  or  eliminated.  To  stimulate  respira- 
tion it  may  be  necessary  to  make  the  patient  conscious  of  his  needs 
by  shouting  in  his  ear,  by  shaking,  flogging  with  a  wet  towel, 
applying  electricity  to  the  cutaneous  surface  intermittently,  or 
by  moderate  walking.  A  good  rate  of  respiration  must  be  kept 
up  even  if  resort  must  be  had  to  the  method  of  artificial  movements 
of  the  arms.  Of  use  may  be  found  hypodermic  doses  of  strychnin, 
2*0  gr.,  cocain  hydrochlorate,  J  gr.,  or  atropin  sulphate,  -^  gr. 
To  stimulate  the  heart  in  the  later  stages,  coffee  and  brandy  are 
indicated. 

Postmortem  Appearances. — The  autopsy  does  not  reveal  any 
local  action  on  the  mucous  membranes  of  the  alimentary  tract. 
Neither  can  any  characteristic  lesion  be  discovered  elsewhere. 
Generally  there  are  found  fulness  of  the  cerebral  vessels,  menin- 
geal  effusions,  and  congestion  of  the  lungs. 

Tests. — Many  of  the  tests  are  based  upon  the  readiness  with 
which  morphin  is  oxidized  and  the  colored  products  obtained  by 
different  degrees  of  oxidation.  These  are  pseudomorphin  and 
compounds  of  morpholin  and  phenanthrene. 

Lejort's  lodic  Acid. — Upon  a  fragment  of  the  morphin  on  a 
dry  white  dish  is  placed  a  drop  of  a  solution  of  iodic  acid,  and  the 
dish  is  then  set  aside  for  ten  minutes.  If  the  brown  color  of  free 


VERATRIN  515 

iodin  appear,  the  spot  is  dried  and,  with  chloroform,  the  iodin  is 
washed  off  until  no  color  remains.  (The  chloroform  residue  will 
turn  blue  with  starch.)  After  drying  the  washed  spot  it  is  wet 
with  a  drop  of  10  per  cent,  ammonia  water,  which,  reacting  with 
morphin  oxidation  products,  gives  a  mahogany  color. 

DELICACY. — A   definite  reaction  is  obtained  with  -g-^Vrr  gr. 

Ferric  Chlorid. — A  fragment  of  the  solid  or  the  residue  sus- 
pected is  moistened  on  a  white  dish  with  neutral  ferric  chlorid  sol- 
ution. A  blue  color  appears,  which  may  be  greenish  if  excess  of 
ferric  chlorid  has  been  used,  destroyed  by  alcohol.  The  color 
is  probably  due  to  a  phenol  compound  of  a  ferrous  base.  This 
reaction  is  given  with  many  aromatic  compounds  containing  the 
phenolic  hydroxyl,  but  no  other  ordinary  alkaloid  gives  it.  The 
morphin  blue  is  changed  to  orange  and  yellow  by  nitric  acid. 

FriJhde's  Molybdic  Acid. — The  reagent  is  a  freshly  made  solu- 
tion of  i  or  2  mg.  of  molybdic  acid  or  ammonium  molybdate  in 
i  c.c.  of  sulphuric  acid.  The  dried  material  on  a  white  dish  is 
treated  with  i  drop  of  the  reagent.  A  purple  color,  changing  to 
violet  and  green,  indicates  morphin.  As  other  alkaloids  give  bluish 
and  greenish  colorations  with  this  reagent,  it  is  advisable  to  identify 
the  color  by  a  control  test  on  a  fragment  known  to  be  morphin. 

DELICACY. — A  decisive  reaction  is  given  by  g-J^-g-  gr. 

Sulphuric  and  Nitric  Acids. — A  trace  of  morphin  on  a  white 
dish  is  touched  with  a  drop  of  concentrated  sulphuric  acid;  a 
colorless  solution  is  formed.  After  standing  for  fifteen  hours  this 
solution  is  treated  with  a  trace  of  nitric  acid,  which  gives  a  bluish- 
violet  color,  changing  to  blood  red. 

DELICACY. — This  reaction  is  decided  with  o.oi  mg.  of  morphin. 

ALKALOIDS    OF    UNKNOWN  CONSTITUTION 

Veratrin. — This  name,  according  to  the  U.  S.  Pharmacopeia, 
covers  a  mixture  of  alkaloids  obtained  from  the  seed  of  Asagraa 
officinalis.  It  is  a  white,  inodorous  powder,  soluble  in  water  and 
alcohol.  An  important  part  of  this  mixture  is  the  alkaloid  cevadin 
or  crystallized  veratrin  (C32H49NO9).  Another  alkaloid  present  is 
jeruin  (C26H37NO3),  with  traces  of  amorphous  veratrin.  Like  the 
aconite  alkaloids,  these  are  quinolin  derivatives. 

Dose  of  fluidextract  of  veratrum  viride  (American  hellebore): 
i  to  3  min.  (0.06-0.18  c.c.).  It  is  a  powerful  cardiac  depressant. 

Toxicology. — Symptoms. — Poisonous  doses  of  veratrum  viride 
or  veratrin  cause  nausea,  vomiting,  abdominal  pain,  weakness, 
feeble  pulse,  giddiness,  loss  of  sight,  dilated  pupils,  drowsiness, 
coma,  with  death  from  asphyxia. 

Fatal  Dose. — The  fluidextract  has  been  fatal  in  doses  of  70  min. 
(4.3  c.c.). 


516  CYCLIC    COMPOUNDS 

Treatment. — The  stomach  should  be  thoroughly  washed  out 
by  the  siphon  tube,  or  emetics  employed.  Tannic  acid  or  vege- 
table astringents  will  precipitate  the  alkaloid.  Cardiac  depres- 
sion may  be  combated  with  atropin  or  strychnin,  or  brandy  hypo- 
dermically.  The  posture  should  be  recumbent,  and  artificial 
respiration  used  if  necessary. 

Tests. — (i)  Veratrin  (U.  S.  P.)  in  dry  fragments  on  a  white 
plate  dissolves  yellow  in  concentrated  sulphuric  acid.  On  stand- 
ing the  yellow  solution  changes  to  bright  red,  and  later  on  to  a 
darker  red  or  crimson,  which  persists  for  hours. 

(2)  Veratrin    dissolves    in    hydrochloric    acid    and    on   boiling 
develops  a  persistent  bright  red  color. 

(3)  One  part  of  veratrin  rubbed  with  6  parts  of  cane-sugar  is 
treated  with  a  few  drops  of  strong  sulphuric  acid.     The  color  de- 
veloped is  yellow,  then  green,  and  finally  blue. 

(4)  Physiologic  Test. — The  ptomains  which  give  color  products 
like  those  described  above  do  not  have  the  same  effects  on  a  live 
frog.     Hypodermic    injection   of   veratrin   causes   vomiting,    slow 
pulse,  convulsions,  and  death. 

Gelsemin  is  a  poisonous  alkaloid  of  Gelsemium  sempervirens,  the 
yellow  jessamine  or  jasmine.  It  is  a  white,  very  bitter,  inodorous 
powder,  used  in  medicine  as  a  nervous  and  arterial  sedative.  In 
overdoses  it  is  a  violent  poison.  The  fluidextract  of  the  root  is 
given  in  doses  of  2  to  10  min.  (0.12-0.65  c.c.).  The  dose  of  the 
alkaloid  is  ^o  to  -£$  gr-  (0.001-0.002  gm.). 

Gelseminin  is  a  brownish  alkaloid  separable  from  the  same  plant. 

Toxicology. — Symptoms. — The  poisonous  effects  are  shown  by 
falling  of  the  eyelids,  double  vision,  dilated  pupils,  great  muscular 
weakness,  depression  of  the  temperature,  pulse,  and  respiration. 
Death  is  by  asphyxia,  the  mind  remaining  clear. 

Fatal  Dose. — Three  teaspoonfuls  of  the  fluidextract  have  caused 
death.  The  symptoms  appear  promptly,  and  death  may  follow 
in  an  hour  or  be  delayed  eight  hours. 

Treatment. — After  the  stomach  has  been  thoroughly  washed 
out  stimulants  are  given,  and  hot  applications  made  to  the  epi- 
gastrium and  extremities.  Digitalis  will  strengthen  the  heart  and 
atropin  the  respiration. 

Tests. — The  alkaloids,  when  touched  with  concentrated  alcohol 
on  a  white  plate,  yield  a  yellow-brown  color.  A  fragment  of  potas- 
sium chromate  or  cerosoceric  oxid  changes  the  color  to  red  and 
purple,  the  final  color  being  green. 

Physiologic  Test. — Administered  hypodermically  to  frogs,  cats, 
or  rabbits,  the  alkaloids  cause  prostration,  convulsions,  dilated 
pupils,  and  asphyxia. 


PTOMAINS  517 

PTOMAINS 

Not  infrequently  cases  of  poisoning  occur  from  eating  foods 
of  animal  origin — such  as  meats,  fish,  cheese,  milk,  custards — 
that  have  become  unwholesome  from  the  products  of  bacterial 
growth.  These  products  are  considered  as  belonging  to  one  of 
the  two  classes,  ptomains  and  protein  toxins.  Leukomains  con- 
stitute a  class  of  substances,  such  as  the  purin  bases  and  creatins, 
some  of  which  are  poisonous,  and  all  of  which  are  produced  by 
the  normal  breaking  down  of  tissue  in  the  living  body,  or,  in  other 
words,  the  splitting  of  protein  by  enzyms  secreted  by  the  body  cells. 
Auto-intoxication,  or  self-poisoning,  such  as  "biliousness"  and 
uremia,  is  the  result  either  of  the  internal  formation  of  ptomains 
or  of  the  undue  accumulation  of  leukomains  in  the  body.  The 
leukomains,  when  not  duly  oxidized  to  urea,  CO2  and  H2O,  often 
cause  serious  disturbance  of  health,  and  the  ptomains  and  toxins 
are  sometimes  highly  toxic.  If  the  phosphorized  fat,  lecithin,  be 
acted  on  by  putrefactive  bacteria,  cholin  may  be  split  off  as  a 
ptomain.  If  the  same  cleavage  be  done  during  life  by  the  body 
cells,  the  cholin  is  a  leukomain,  and  if  not  normally  oxidized,  causes 
auto-intoxication. 

Ptomains  are  soluble  basic  bodies  formed  by  the  action  of  certain 
micro-organisms  on  putrefying  protein  material.  The  amino- 
acids  ornithin  and  lysin,  constituents  of  pure  proteins,  subjected 
to  bacterial  action,  split  off  CO2  and  change  to  putrescin  and 
cadaverin  (p.  500).  Some  of  them  are  active  poisons,  but  others, 
like  the  methylamins  and  ethylamins,  are  harmless.  They  are 
alkali-like  in  some  respects,  and  hence  were  formerly  termed  cad- 
averic alkaloids.  They  are  strongly  basic  and  combine  with  acids 
to  form  salts.  Like  the  proteins  from  which  they  are  derived,  they 
are  precipitated  with  the  chlorids  of  mercury,  gold,  and  platinum; 
with  picric  acid,  tannic  acid,  phosphomolybdic  acid,  and  phospho- 
tungstic  acid.  Having  these  reactions  in  common  with  vegetable 
alkaloids,  they  may  be  considered  as  related  to  them.  However, 
many  of  them  differ  from  true  alkaloids  in  constitution,  having 
their  nitrogen  in  an  open-chain  molecule  of  the  fatty  series,  and 
belonging  to  the  class  of  amins  (p.  497).  These  ptomains,  which 
do  not  contain  a  closed  chain  (acyclic),  are  subdivided  into  those 
free  from  oxygen  and  those  containing  that  element.  The  acyclic 
free  from  oxygen  comprise  the  methylamins,  butylamin,  amylamin, 
neuridin,  saprin,  cadaverin,  putrescin,  spermin,  mydalein.  The 
acyclic  ptomains  containing  oxygen  include  cholin,  neurin,  mus- 
carin,  betain,  gadinin,  mytilotoxin,  and  a  few  others. 

In  the  following  list  are  included  the  ptomains  which  have  the 
nitrogen  in  a  closed  chain  (pyridin  ring)  like  true  alkaloids  (cyclic), 


£  1 8  CYCLIC    COMPOUNDS 

and  those  as  yet  unclassified:  collidin,  parvolin,  corindin,  morrhuin, 
asellin,  typhotoxin,  tetanin,  spasmotoxin,  tetanotoxin,  pyocyanin, 
tyrotoxicon. 

Of  the  above  list,  a  small  number  of  ptomains  are  known  to 
be  injurious  in  foods.  These  are  tyrotoxicon  of  milk,  cream  puffs, 
ice  cream,  and  cheese;  mytilotoxin  of  mussels  and  oysters;  muscarin 
of  mushrooms  and  meat;  and  from  spoiled  fish  and  meat,  cholin, 
neuridin,  neurin,  cadaverin,  putrescin.  While  they  are  decom- 
position products  of  protein,  apparently  they  may  be  engendered 
in  tissues  still  living,  such  as  fresh  oysters  and  mussels.  To  pro- 
duce them  is  required  a  certain  favorable  combination  of  special 
micro-organisms,  protein,  air,  and  temperature.  They  are  un- 
stable, changing  in  a  short  while  through  many  stages.  In  most 
cases  decomposition  has  not  gone  far  enough  to  make  the  food 
offensive.  The  toxicity  may  be  great  when  there  is  no  taint  per- 
ceptible to  smell  or  taste. 

Symptoms. — These  make  their  onset  soon  after  eating  the 
poisoned  food.  They  may  be  described  broadly  as  the  symptoms 
of  gastro-enteritis,  with  depression  and  other  nervous  disturbances. 
There  are  in  most  cases  marked  thirst,  salivation,  nausea,  vomiting, 
abdominal  pain,  diarrhea,  cramps  in  the  legs,  great  prostration, 
chills,  feeble  pulse,  dilated  pupils,  drowsiness  or  delirium,  numb- 
ness, paralysis,  exhaustion,  and  collapse. 

Sometimes  the  postmortem  reveals  inflammation  of  the  stomach 
and  bowels,  though  fatal  cases  occur  which  are  free  from  morbid 
changes  in  the  anatomy  of  the  digestive  tract. 

Cholin  (C15H15NO2)  (bilineurin)  is  a  complex  amin  occurring 
in  the  bile  of  animals,  in  the  human  placenta,  in  the  yolks  of  eggs, 
in  hops,  and  in  fungi. 

Cholin  is  formed  by  treating  an  aqueous  solution  of  trimethyl- 
amin  with  ethylene  chlorhydrin: 

N(CH3)3  +  C2H4C10H  f  H20  =  C2H4OHN(CH3)3OH  +  HC1. 

Cholin. 

The  lecithins  of  the  animal  corpse  produce  cholin  during  the 
first  forty-eight  hours  of  putrefaction.  On  and  after  the  third 
day  cholin  diminishes,  while  other  closely  related  bodies,  such  as 
neuridin,  putrescin,  and  cadaverin  (ptomains),  appear  and  increase 
daily.  Muscarin  can  be  made  by  oxidizing  cholin  with  nitric  acid. 
The  effect  of  heat  is  to  split  cholin  into  glycol  and  trimethylamin. 

Properties. — It  is  a  syrupy  fluid,  soluble  in  water  and  alcohol, 
and  strongly  alkaline.  It  absorbs  carbon  dioxid  from  the  air  like 
other  strong  bases,  and  forms  a  hydrochlorid  which  crystallizes 
in  plates  like  cholesterin.  In  large  doses  its  action  is  poisonous. 


MUSCARIN  519 

Lecithin  is  a  complex  body  commonly  found  in  yolk  of  egg, 
brain  and  nerve  tissue,  blood,  pus,  milk,  etc.  The  several  varieties 
are  compounds  of  cholin  and  glycerophosphoric.  acid  with  the 
acids  of  fat.  This  composition  is  shown  by  the  following  formula 
which  gives  glyceryl  united  to  two  stearic  acid  groups  and  one  of 
phosphoric  acid,  linking  the  cholin: 

O  .  C18H350 

QgH^O        //(CH3)3 
O.P03H.C2H4N-OH. 

With  alkalis  they  saponify,  yielding  the  fatty  acids,  the  glycero- 
phosphoric acid,  and  cholin.  Like  the  true  fats,  they  are  soluble 
in  ether. 

Neurin,  C5H13NO,  is  an  amin  derivative  occurring  as  a  prod- 
uct of  decomposition  in  the  tissues  of  the  brain  and  suprarenal 
capsule.  It  is  one  of  the  ptomains  of  muscular  tissue.  It  can  be 
formed  by  boiling  cholin  with  baryta  water  and  thereby  abstracting 
the  elements  of  water: 

C2H3OHN(CHS)3  +  H20  =  C2H4OHN(CH3)3OH 

Neurin.  Cholin. 

It  is  a  poison  much  more  powerful  than  cholin,  the  symptoms 
resembling  those  of  obstruction  of  the  bowel,  with  nausea,  pain, 
and  depression. 

Diamins. — This  class  of  compounds,  containing  two  NH2  groups, 
has  several  representatives,  basic  in  character,  among  the  putrid 
products,  viz.:  trimethylenediamin,  H2N .  (CH2)3NH2,  found  in 
the  cultures  of  comma  bacillus;  tetramethylenediamin,  or  putrescin, 
H2N  .  (CH2)4NH2,  found  in  cultures  of  comma  bacillus  and  putrid 
flesh;  pentamethylenediamin  or  cadaverin,  H2N  .  (CH2).NH2,  occur- 
ring in  the  later  stages  of  putrefaction,  after  cholin  has  disappeared, 
as  a  basic  liquid  with  a  disagreeable  odor;  neuridin,  isomeric  with 
cadaverin,  and  produced  with  cholin  as  an  early  putrid  product; 
mydalein,  a  diamin  of  unknown  structure,  product  of  putrefaction, 
actively  poisonous,  causing  dilated  pupils,  diarrhea,  convulsions, 
and  paralysis  (p.  500). 

Amanitin  (CH3 .  CHOH  .  N  .  OH  .  (CH3)3)  (isocholin)  occurs 
as  an  alkaloid  in  the  red,  fleshy  mushroom,  Agaricus  muscarius, 
or  fly  agaric,  which  is  poisonous  to  flies  and  man.  It  is  isomeric 
with  cholin,  and  can  be  prepared  by  introducing  methyl  into 
aldehyd  ammonia.  Nitric  acid  oxidizes  it  to  muscarin. 

Muscarin,  CH2CH(OH)2OHN  .  (CH3)3,  is  found  in  the  mush- 
room, Agaricus  muscarius,  and  is  also  a  ptomain.  Chemically, 


520 


CYCLIC    COMPOUNDS 


it  is  related  to  amanitin,  neurin,  and  cholin,  and  can  be  produced 
synthetically  from  the  latter. 

Properties. — When  dry,  it  occurs  in  odorless  and  tasteless, 
irregular  crystals,  which  deliquesce  to  form  a  syrupy  liquid,  strongly 
alkaline,  soluble  in  water  and  in  alcohol,  insoluble  in  chloroform 
and  in  ether.  It  can  be  reduced  to  cholin  and  oxidized  to  betain. 
It  breaks  up  into  trimethylamin.  Precipitated  by  excess  of  plati- 
num chlorid,  it  forms  octahedral  crystals,  while  the  chlorplatinate 
of -cholm  crystallizes  in  plates. 

Toxicology. — Symptoms. — Muscarin  is  far  more  poisonous  than 
cholin  or  neurin,  and  is  the  active  cause  of  the  symptoms  of  mush- 
room poisoning.  These  are  vomiting,  griping  pains  in  the  stomach 
and  intestine,  slow  pulse,  ending  in  arrest  of  the  heart's  action; 
contraction  of  the  pupils,  salivation,  and  fatal  collapse.  Alarming 
symptoms  may  follow  -^  gr.  (i  mg.). 

Treatment. — Its  physiologic  antagonist  and  antidote  is  atropin. 
Stimulants,  morphin,  and  strychnin  are  also  of  service. 

TOXINS 

Toxins  are  poisonous  bases  produced  in  the  animal  body  by 
certain  bacteria,  which  also  cause  infectious  diseases.  Such  are 
diphtheria  toxin,  typhotoxin  of  typhoid  fever,  tetanin,  and  spasmo- 
toxin  of  tetanus. 

Food  Toxins. — The  protein  toxins  that  cause  food  poisoning 
are  either — (i)  the  poisonous  products  of  specific  bacteria,  not 
putrefactive,  growing  in  the  meat  after  slaughter;  or  (2)  they  are 
products  of  specific  bacteria  infecting  the  tissues  of  the  food  animals 
before  slaughter. 

(i)  A  common  form  is  botulism  or  sausage  poisoning,  caused 
by  the  Bacillus  botulinus  contaminating  ham,  sausage,  and  fish. 
Other  powerful  toxins  have  been  developed  by  certain  species  of 
bacteria,  like  Proteus  vulgaris,  growing  in  pork  and  beef  sausages. 
Sausage  poisoning  manifests  itself  usually  within  twenty-four  hours, 
sometimes  as  soon  as  half  an  hour,  though  the  onset  may  be  de- 
layed for  a  week. 

The  symptoms  of  sausage  poisoning  are  epigastric  discomfort, 
belching,  nausea,  vomiting,  gripes,  diarrhea,  followed  by  consti- 
pation. After  a  few  days  the  nervous  symptoms  appear:  dilated 
pupils,  blindness,  falling  of  the  lids,  paralysis  of  the  tongue  and 
pharynx,  and  loss  of  voice.  The  secretions  may  be  suppressed, 
the  pulse  irregular,  and  the  muscles  weak  to  exhaustion.  In  a  few 
cases  there  are  somnolence,  giddiness,  convulsions,  paralysis,  and 
possibly  acute  nephritis.  Death  may  follow  delirium  and  coma, 
or  a  favorable  turn  may  lead  to  slow  recovery  after  many  days. 


TOXINS  521 

The  postmortem  appearances  have  been  in  the  nature  of  hyper- 
emia  of  meninges,  lungs,  spleen,  kidneys,  liver,  and  alimentary 
tract.  Nothing  has  been  found  characteristic  of  botulism. 

(2)  The  toxins  of  the  other  class  result  from  the  activities  of 
the  pathogenic  bacteria  before  the  animals  are  killed.  The  meat 
from  cows  and  calves  that  have  had  pyemia,  septicemia,  or  specific 
enteritis  will  cause  symptoms  something  like  arsenic  poisoning, 
cholera,  or  typhoid  fever.  These  are  headache,  vomiting,  profuse 
diarrhea,  gripes,  chills,  and  fever. 

Treatment. — The  efforts  of  nature  to  remove  the  poison  should 
be  promoted  by  free  potations  of  warm  water  and  salt,  followed 
by  mild  laxatives  and  high  irrigation  of  the  intestines  with  enemas. 
Excessive  vomiting,  purging,  and  pain  are  to  be  relieved  by  hypo- 
dermic injections  of  morphin.  Stimulants  are  needed,  and  sub- 
cutaneous injections  of  normal  salt  solution  will  be  helpful. 

Resemblances  Between  Ptomains,  Toxins,  and  Vegetable 
Alkaloids. — A  study  of  the  symptoms  narrated  above  shows  certain 
points  of  resemblance  to  the  symptoms  caused  by  alkaloidal  poisons. 
For  example:  somnolency  may  be  mistaken  for  the  effects  of 
morphin;  dilated  pupils  and  delirium  are  prominent  signs  of  poison- 
ing from  plants  yielding  atropin;  paralysis,  numbness,  convulsions, 
and  stupor  may  be  found  after  doses  of  conium  and  gelsemium. 

The  chemical  tests  dependent  on  color  changes  due  to  oxidiz- 
ing agents,  when  applied  to  vegetable  alkaloids,  give  results  closely 
resembling  those  caused  in  certain  ptomains,  so  that  mistakes 
have  occurred  in  the  work  of  expert  chemists.  The  symptoms  of 
the  case,  the  physiologic  tests  on  lower  animals,  and  all  known 
chemical  tests  must  be  studied  and  harmonized  before  the  analyst 
can  be  certain  that  he  is  not  dealing  with  ptomains,  but  that  he 
has  detected  morphin,  atropin,  coniin,  nicotin,  strychnin,  veratrin, 
or  colchicin. 

The  various  methods  employed  for  separation  of  the  alkaloids 
are  none  of  them  perfectly  successful  in  excluding  the  ptomains. 
Perhaps  the  best  yet  devised  is  that  known  as  the — 

Kippenberger  Process. — Separation  is  accomplished  by  virtue 
of  the  mixture  of  tannic  acid  and  glycerin,  which  dissolves  the 
vegetable  alkaloids,  but  leaves  ptomains  and  toxalbumins  undis- 
solved.  The  alkaloids  are  separated  from  one  another  by  shaking 
the  liquid  with  successive  immiscible  solvents  in  a  separating  funnel 
with  a  stopcock  (Fig.  83).  Each  solvent  extracts  a  group,  which 
is  left  on  evaporation  of  the  solvent,  and  the  alkaloid  is  detected  in 
the  residue  by  appropriate  tests. 

The  material,  finely  minced,  is  macerated  at  40°  C.  (104°  F.) 
in  a  10  per  cent,  solution  of  tannic  acid  in  glycerin  for  two  days. 
It  is  then  put  in  a  bag  of  straining  cloth  and  the  fluid  part  pressed 


522 


CYCLIC    COMPOUNDS 


out.  This  fluid  part  is  heated  to  between  60°  C.  (140°  F.)  and 
70°  C.  (158°  F.)  for  two  hours;  cooled  and  filtered.  The  filtrate  is 
shaken  with  petroleum  ether,  which  separates  the  fats.  Any  petro- 
leum ether  not  separated  from  the  liquid  is  removed  by  evaporation 
on  a  water-bath,  and  the  liquid  is  now  shaken  with  chloroform  while 
still  acid.  This  chloroform-acid  extract  removes  aconitin,  can- 
tharidin,  colchicin,  digitalin,  jervin,  narcotin,  picrotoxin,  and  traces 
of  strychnin,  veratrin,  brucin,  delphinin,  and  narcein.  The  liquid, 
made  alkaline  with  potassium  hydroxid,  is  again  shaken  with 
another  portion  of  chloroform,  which  now  removes  apomorphin, 
atropin,  brucin,  codein,  coniin,  emetin,  nicotin,  pilocarpin,  spartein, 
strychnin,  veratrin.  Potassium  bicarbonate  is  now  added  to 
change  any  excess  of  hydroxid  to  carbonate,  and  the  mixture  shaken 
with  chloroform  containing  10  per  cent,  of  alcohol,  which  extracts 
morphin  and  narcein.  The  liquid  is  lastly  saturated  with  sodium 
chlorid  and  shaken  with  chloroform  containing  15  per  cent,  of 
ether,  which  removes  strophanthin. 

Infection  Toxins. — In  the  cells  of  bacteria  are  built  up 
poisonous  substances  which  may  be  retained  or  may  pass  out  by 
diffusion.  The  filtrate  of  a  culture  of  diphtheric  bacilli  is  poisonous 
because  of  the  soluble  toxin  excreted  by  the  bacilli.  In  a  few  days 
toxemia  is  produced  by  absorption  of  toxins  from  the  diphtheric 
membrane  in  the  throat. 

The  filtrate  of  a  typhoid  culture  is  harmless  because  the  toxin 
has  been  retained  by  the  typhoid  bacillus.  But  if  the  precipitated 
bacilli  be  dried,  pulverized,  and  suspended  in  water,  the  intracel- 
lular  toxin  is  liberated  and  the  mixture  is  poisonous.  In  the  period 
of  invasion  of  typhoid  fever  the  bacilli  find  access  to  the  circulation 
and  multiply  there.  As  they  die  from  day  to  day,  their  intracel- 
lular  toxins  are  set  free  and  cause  the  fever  of  a  septicemia  or 
bacteremia  until  the  bacilli  are  all  gone. 

Antitoxins. — When  the  body  is  infected  by  a  toxin  a  defen- 
sive protein  of  unknown  composition  is  formed  in  the  blood,  which 
combines  with  and  neutralizes  the  toxin.  The  antitoxin  of  diph- 
theria is  produced  artificially  by  injecting  horses  with  a  culture  of 
the  diphtheria  bacilli.  By  gradually  increasing  doses  the  animal 
acquires  immunity,  and  its  serum,  drawn  from  the  vessels,  is  so  rich 
in  the  antitoxin  that  when  injected  into  man  it  gives  immunity  from 
or  cures  the  infection  of  diphtheria. 

Agglutinins,  Precipitins,  and  Lysins.— When  the  body  is  in- 
jected with  certain  bacteria  or  cells,  antibodies  are  developed  in 
the  blood.  These  bodies  cause  a  reaction  when  they  are  mixed 
with  the  special  injected  material. 

Agglutinins. — The  blood-serum  of  a  case  of  infectious  disease 
contains  agglutinin,  which  has  the  property  of  clumping  together 


OPSONINS  523 

the  specific  bacteria  in  a  culture.  Thus,  in  Widal's  test  for  typhoid 
fever,  blood  from  the  patient  is  added  to  a  fresh  culture  of  typhoid 
bacilli,  and  if  the  case  be  typhoid  fever,  the  bacilli  adhere  in  tangled 
masses.  They  are  not  killed,  but  held  in  check,  so  that  they  do 
not  multiply  and  are  more  easily  exterminated. 

A  precipitin  is  an  antibody  which  acts  as  a  protective  against 
foreign  proteins  in  the  blood.  It  confers  upon  the  serum  the 
special  property  of  precipitating  from  solution  the  protein  that 
excited  its  production. 

Lysins  are  cell-destroying  substances  developed  in  the  serum  by 
the  injection  of  non-fatal  doses  of  bacteria  or  their  products.  Bac- 
teriolysins  are  bacteria-destroying,  soluble  proteins  of  the  blood 
plasma.  Hemolysins  are  able  to  destroy  the  red  blood-cells  of 
another  species  of  animal.  An  autolysin  destroys  cells  in  the 
animal's  own  body;  a  homolysin,  those  in  an  animal  of  the  same 
species;  a  heterolysin,  those  in  an  animal  of  different  species. 
These  lysins  consist  of  two  substances  called  the  immune  body  and 
the  complement.  The  lysins  cannot  act  upon  their  objects  of  attack 
without  an  intermediate  substance.  This  substance,  the  immune 
body,  has  two  chemical  affinities:  (i)  It  is  specific  for  each  lysin 
that  is  developed,  and  (2)  it  acts  by  uniting  with  the  bacterial 
product  on  the  one  hand  and  the  blood  complement  on  the 
other. 

Opsonins  (caterers)  are  certain  elements  of  blood-serum,  differ- 
ent from  lysins  and  antitoxins,  which  unite  chemically  with  invading 
bacteria  and  alter  them  so  that  the  leukocytes  can  phagocyte  and 
destroy  them.  Each  variety  of  disease  germ  has  its  corresponding 
•opsonin.  The  amount  of  opsonins  in  the  blood  of  an  individual 
determines  his  susceptibility  to  bacterial  invasion.  To  measure 
this  resistance  of  the  patient,  as  compared  with  that  of  a  healthy 
person,  is  to  find  out  his  "opsonic  index." 

To  do  this,  cultures  are  made  of  a  mixture  of  the  serum  of  the 
patient's  blood  with  washed  leukocytes  and  emulsion  of  the  specific 
bacteria.  At  the  same  time  a  control  experiment  is  made  with 
normal  blood-serum.  The  average  of  germs  to  leukocytes  is 
counted  and  compared  in  the  two  experiments.  The  result  is 
.stated  as  high,  normal,  or  low  opsonic  index.  Cases  of  bacterial 
infection  with  normal  or  low  index  are  treated  by  inoculating  the 
patient  with  a  vaccine  of  the  specific  bacteria,  watching  the  opsonic 
index.  By  this  means  it  is  intended  to  stimulate  the  tissues  to  an 
increased  production  of  opsonins  until  the  level  is  maintained 
higher  than  normal  and  the  invading  bacteria  are  disposed  of. 


524  CYCLIC    COMPOUNDS 

PROTEINS  OR  ALBUMINOUS  MATTER 

THE  compounds  considered  under  this  head  are  the  post- 
mortem representatives  of  the  protoplasm  which  constitutes  the 
indispensable  basis  of  life  in  plants  and  animals.  The  animal 
body  is  especially  rich  in  these  proteins  or  albuminous  substances, 
as  they  are  sometimes  called.  Apparently,  they  are  all  formed 
originally  by  plants  only.  Animals  take  the  fundamental  structure 
in  vegetable  food  and  afterward  make  some  changes  in  them, 
but  do  not  make  them  by  synthesis  of  their  elements. 

They  belong  to  the  class  of  colloids,  as  most  of  them  do  not  crys- 
tallize nor  diffuse  through  the  membrane  of  a  dialyzer  without 
difficulty,  owing  to  the  large  size  of  the  molecule.  They  are  non- 
volatile; without  odor  or  taste;  some  are  soluble  in  water,  others 
are  insoluble;  all  of  them  are  optically  active,  turning  the  polarized 
ray  to  the  left.  All  of  them  contain  carbon,  hydrogen,  oxygen, 
nitrogen,  and  traces  of  mineral  salts.  Other  constituents  found 
in  some  of  them  are  sulphur,  phosphorus,  and  iron. 

It  is  not  known  if  their  constitution  be  definite;  it  is  certainly 
very  complex.  The  great  number  and  variety  of  proteins  in 
plants  and  animals  is  explained  by  the  fact  that  many  of  them 
contain  as  many  as  100  asymmetric  carbon  atoms  (p.  425),  thus 
permitting  special  isomerids,  enormous  in  number,  and  possible 
modifications  of  properties  to  an  unlimited  extent.  These  differ- 
ences in  spatial  arrangement  of  the  atoms  are  frequently  of  greater 
importance  for  the  direction  of  vital  processes  than  coarser  differ- 
ences in  chemical  structure. 

By  blending  certain  amino-acids  Fischer  has  succeeded  in  pro- 
ducing artificially  polypeptid  bodies  having  some  resemblance  to 
peptones  in  properties  and  reactions,  but  no  structural  formula 
can  be  made  to  represent  pure  protein.  Ignorance  of  their  true 
constitution  is  the  excuse  for  a  classification  less  accurate  than  is 
desirable,  based  upon  their  differences  in  behavior  when  heated, 
when  treated  with  acids  and  alkalis,  and  when  salted  out.  Some 
of  them  exist  already  formed  in  the  animal  tissues  and  fluids,  and 
are  sometimes  referred  to  as  native  proteins  (albumins,  globulins, 
nucleo-albumins).  Others  are  products  of  the  action  of  heat  and 
chemicals  or  of  enzyms  upon  the  native  proteins,  and  hence  are 
referred  to  as  derived  proteins  (albuminates,  proteoses,  peptones). 

The  simple  proteins,  albumin  and  globulin,  are  present  in  all  the 
fluids  and  solids  of  the  body  except  the  tears  and  sweat.  Their 
molecular  weights  have  been  estimated  as  about  10,000,  and  while 
the  molecules  must  be  variable  in  size,  all  are  very  large,  their  per- 
centage composition  averaging  as  follows:  carbon,  52;  hydrogen, 
7;  nitrogen,  16;  oxygen,  22;  sulphur,  i;  phosphorus,  0.5. 


PROTEINS  525 

Decompositions. — By  the  action  of  hydrochloric  acid  the  nitro- 
gen of  the  proteins  is  divided  among  three  fractions  of  the  mole- 
cule: ammonia,  amino-acids,  and  diamino-acids .  Alkalis  have  the 
property  of  separating  a  portion  of  the  nitrogen  as  ammonia.  If 
the  proteins  be  boiled  with  caustic  alkalis,  only  a  part  of  the  sulphur 
goes  off  in  a  sulphid  combination,  the  remainder  being  converted 
to  sulphate  by  fusion  with  niter  and  potassium  carbonate.  This 
is  proof  that  the  protein  molecule  contains  at  least  2  atoms  of 
sulphur.  Under  oxidizing  agencies  profound  changes  occur,  the 
products  being  acids,  aldehyds,  ketones,  amino-acids,  hydrocyanic 
acid,  carbon  dioxid,  and  ammonia. 

Agents  which  cause  hydrolysis,  such  as  ferments  and  dilute 
acids,  split  up  the  simple  proteins  into  other  proteins  of  lower  molec- 
ular weight — proteoses  and  peptones — which  no  longer  coagulate 
when  heated,  and  which,  owing  to  the  diminished  size  of  the  mole- 
cule, readily  diffuse.  The  final  products  of  hydrolytic  cleavage 
by  ferments  or  prolonged  boiling  with  acids  are  of  known  constitu- 
tion, are  supposed  to  be  preformed  like  the  stones  in  a  building, 
and  in  time  a  study  of  them  as  nuclei  may  lead  to  a  knowledge  of 
their  mode  of  union  in  the  protein  molecule.  They  are  the 
monoamino-acids,  such  as  leucin,  glycocoll,  and  alanin;  the  amino- 
diacids,  aspartic  and  glutamic;  the  diamino-acetic  and  diamino- 
valerianic  acids  (ornithin);  the  dipeptids,  prolin  and  oxyprolin; 
the  oxyacid,  serin;  the  hexon  bases  or  diamino-acids,  lysin,  arginin, 
and  histidin;  the  isocyclic  nuclei  of  tyrosin  and  phenylalanin;  the 
heterocyclic  nucleus  of  tryptophan;  the  carbohydrate  nucleus, 
glucosamin;  the  sulphur  compound,  cystin.  Each  a.  acid  has 
the  acid  group  CO  OH  at  one  end  and  the  basic  amino-group  NH2 
substituted  for  a  hydrogen  atom  on  the  nearest  carbon  atom.  The 
rest  of  the  compound  may  be  regarded  as  a  radical  either  of  the 
open  chain  or  the  cyclic  series.  The  general  formula  then  may 
be  stated  as: 

/NH2 
R-CH-COOH. 

It  is  possible  for  the  acid  group  of  one  to  unite  with  the  basic  group 
of  another  in  an  indefinite  number  of  permutations.  The  various 
proteins  have  different  kinds,  numbers,  and  arrangements  of  these 
relatively  few  amino-acids. 

Putrefaction  is  the  breaking  up  of  proteins  by  the  growth 
of  certain  bacteria,  the  fetid  products  of  intestinal  putrefaction 
being  phenol,  indol,  skatol,  ptomains,  volatile  fatty  acids,  methyl 
mercaptan,  ammonia,  and  hydrogen  sulphid.  Part  of  the  phenol 
and  skatol  are  absorbed,  and  in  the  liver  are  joined  or  conjugated 
with  potassium-acid  sulphate,  being  finally  eliminated  by  the  urine. 


526  CYCLIC    COMPOUNDS 

The.  other  end-products  remain  for  a  while  in  the  intestines  and 
are  ejected  as  feces  and  flatus  (p.  396). 

Coagulation. — The  simple  soluble  proteins,  when  acidulated 
and  heated,  become  denatured  into  insoluble  material.  The  process 
of  change  is  called  coagulation.  The  original  substance  cannot 
be  reproduced  by  any  manipulation  of  this  white  insoluble  solid, 
which  in  this  respect  differs  from  a  precipitated  protein.  The 
different  proteins  coagulate  at  different  temperatures;  none  coagu- 
lates by  heating  alkaline  solutions.  Complete  coagulation  re- 
quires the  combination  of  heat  applied  to  an  acid  solution  contain- 
ing 5  per  cent,  of  neutral  salts.  (See  Albuminuria.) 

Precipitation  in  an  insoluble  combination  is  produced  by 
adding  the  mineral  acids,  especially  nitric  acid;  by  some  organic 
acids  in  strong  solutions  of  neutral  salts;  by  potassium  ferrocyanid 
with  acetic  acid;  by  acid  solution  of  tannin;  by  picric  acid,  carbolic 
acid,  salicylsulphonic  acid,  trichloracetic  acid,  by  sodium  tung- 
state;  by  phosphomolybdic  acid,  by  potassiomercuric  iodid;  by 
solutions  of  metallic  salts,  such  as  mercuric  chlorid,  cupric  sul- 
phate, lead  acetate,  and  silver  nitrate;  by  alcohol  and  chloral; 
by  saturated  ammonium  sulphate,  which  precipitates  all  except 
peptone. 

Experiments. — Having  made  a  solution  of  albumin  by  shaking 
white  of  egg  in  a  bottle  with  five  times  as  much  water,  and  separat- 
ing the  sediment,  proceed  to  show  coagulation  by  heat,  acids, 
and  by  the  other  reagents  named  above.  Using  fresh  portions 
each  time,  apply  the  following  tests  also. 

Color  Reactions. — Any  protein,  such  as  the  glutin  in  dry  bread, 
will  give  the  xanthoproteic  reaction,  which  is  the  yellow  color 
caused  by  the  action  of  concentrated  nitric  acid,  changing  to  orange 
on  the  addition  of  excess  of  ammonium  hydroxid.  This  indicates 
the  presence  of  the  benzene  ring,  and  is  given  by  tryptophan, 
tyrosin,  or  phenylalanin  (pp.  459  and  500). 

Biuret  Reaction. — A  violet  to  pink  color  obtained  when  a  hot 
Fehling's  solution  is  overlaid  with  the  protein — after  complete 
hydrolysis  the  products  do  not  give  this  reaction. 

Frohde's  Reaction. — A  solution  of  molybdic  acid  in  sulphuric 
acid  gives  to  solid  proteins  a  blue  color  (p.  515). 

Millon's  Reaction. — This  reagent  (mercuric  nitrate)  imparts  a 
purple-red  color  to  pieces  of  solid  proteins  when  they  are  boiled  in 
it.  It  is  also  given  by  the  phenol  group  in  the  tyrosin  nucleus 
(pp.  457  and  500). 

Liebermann's  reaction  is  the  violet-blue  color  obtained  when 
proteins  are  dissolved  in  boiling  hydrochloric  acid. 

Adamkiewicz's  reaction  requires  the  solution  of  the  protein  in 
hot  glacial  acetic  acid.  When  cool,  it  is  overlaid  with  concentrated 


PROTEINS  527 

sulphuric  acid.  A  violet  or  purple  band  appears  at  the  line  of  con- 
tact. It  is  due  to  the  tryptophan  group  (p.  500). 

Molisch's  reaction  (p.  473)  indicates  glucosamin  or  some  other 
carbohydrate  (p.  434). 

FALLACIES. — The  positive  detection  of  a  protein  requires  all 
of  these  color  reactions.  No  one  of  them  can  be  considered  as 
characteristic,  as  similar  colors  are  caused  by  alkaloids  and  other 
nitrogenous  organic  substances. 

Classification  of  Proteins.— There  are  three  groups  of  animal 
proteins:  Simple  Proteins,  Conjugate  Proteins,  and  Derived  Pro- 
teins: I.  SIMPLE  PROTEINS — (i)  Protamins ;  (2)  Histons ;  (3) 
Albumins;  (4)  Globulins;  (5)  Scleroproteins;  (6)  Phosphoproteins. 
II.  CONJUGATE  PROTEINS — a,  chromoproteins;  &,  glucoproteins; 
c,  nucleoproteins.  III.  DERIVED  PROTEINS — a,  infraproteins; 
by  proteoses;  c,  peptones;  d,  polypeptids. 

1.  PROTAMINS. — In  the  heads  of  the  spermatozoa  of  fish  are  found 
nucleoproteins  which  yield  basic  substances  that  resemble  simple 
albumins  in  some  reactions,  though  not  in  all.     Their  molecules 
contain  the  groups  that  give  the  biuret  reaction  and  are  precipitated 
like  alkaloids,  but  not  the  groups  that  coagulate  when  heated  and 
respond  to  Millon's  reagent.     They  yield  only  a  small  number  of 
amino-acids    on    hydrolysis.      Hence    they    are    regarded    as    the 
simplest  of  all  proteins.     They  are  called  protamins  and  differ 
according   to   their   source;   thus,   salmin   (salmon),    C30H57N17O6; 
sturin  (sturgeon),  C34H71N17O9,  etc.     When  hydrolyzed  by  trypsin 
they  first  yield  substances  analogous  to  peptone  called  protons,  and 
finally  split  up  into  simpler  products,  among  which  are  bases  con- 
taining  6   atoms    of  carbon,   hexons,   named  histidin,  C6H9N3O2; 
arginin,  C6H14N4O3;  and  lysin,  C6H14N2O2.     As  the  more  complex 
proteins  also  yield  hexons,  it  is  probable  that  all  contain  a  protamin 
nucleus. 

2.  HISTONS. — These  closely  resemble  the  protamins,  differing  in 
the  complexity  of  the  molecule,  which  in  histons  is  more  like  that 
of  a  pure  albumin  in  a  simpler  form.     The  protamins  seem  to  be 
constituents  of  the  more  highly  developed  histons,  which  yield  a 
greater  number  of  amino-acids  on  hydrolysis.     Histons  are  like 
the  albumoses  in  their  reactions,  are  basic,  and  most  of  them  con- 
tain iron.     Among  them  is  globin  of  the  red  blood-corpuscle  and 
nucleohiston  from  the  thymus  gland  of  the  calf  (p.  532).     They 
are  distinguished  by  being  precipitable  with  ammonia. 

3.  ALBUMINS. — These  dissolve  in  pure  water,   coagulate   when 
heated,  and  precipitate  from  solutions  saturated  with  ammonium 
sulphate.     They  include  serum-albumin  of  the  blood,  ovalbumin 
of  egg,  lactalbumin  of  milk,  and  myo-albumin  of  muscle. 

4.  GLOBULINS. — These  do  not  dissolve  in  pure  water,  but  are 


528  CYCLIC    COMPOUNDS 

soluble  in  a  0.5  to  i  per  cent,  solution  of  neutral  salts,  coagulate  by 
heat,  precipitate  from  solutions  saturated  with  magnesium  sulphate 
or  sodium  chlorid,  or  by  addition  of  an  equal  volume  of  saturated 
solution  of  ammonium  sulphate.  They  include  serum-globulin, 
lactoglobulin,  myoglobulin  and  its  derivative  myosin,  fibrinogen 
and  its  derivative  fibrin  of  clotted  blood. 

5.  SCLEROPROTEINS. — Under  this  head  are  grouped  the  proteins, 
which   differ   somewhat   among   themselves   and  yet   are   alike   in 
resisting  the  action  of  the  agents  which  dissolve  the  other  proteins 
referred  to  above.     They  are  the  horny,  elastic,  tough,  gelatinous 
substances  found  in  bone,  cartilage,  connective  tissue,  epidermis, 
hair,  etc.     The  list  given  below  contains  the  important  members 
of  skeletal  origin. 

Keratins  are  characteristic  of  the  skin,  hair,  and  nails.  They 
are  rich  in  loosely  combined  sulphur,  which  appears  to  take  the 
place  of  oxygen  in  a  simple  protein,  and  which  forms  a  black 
sulphid  with  lead  hair-dyes.  They  are  not  affected  by  gastric  juice 
or  trypsin,  but  dissolve  in  warm  caustic  alkalis.  They  dissolve  in 
water  heated  under  pressure  to  i5o°-2oo°  C.  (302°-392°  F.), 
but  do  not  gelatinize.  They  respond  to  the  xanthoproteic  and 
Millon's  reactions. 

Elastins  are  found  in  the  yellow  elastic  tissue  of  ligaments. 
They  are  digested  by  the  gastric  juice  and  by  trypsin;  are  insol- 
uble in  water  unless  heated  under  pressure;  are  soluble  in  nitric 
acid  and  in  boiling  alkalis. 

Collagens  may  be  considered  under  two  varieties:  ossein  of  bone 
and  chondrogen  of  cartilage  and  tendons.  Dry  collagen  is  yellow, 
hard,  and  insoluble.  By  boiling  in  water  or  dilute  acid  it  swells 
up  and  forms  gelatin  or  glue,  which  makes  a  clear  solution,  turn- 
ing to  jelly  when  cooled.  Gelatin  is  soluble  in  gastric  juice  and 
trypsin,  but  is  not  coagulated  by  heat  nor  precipitated  by  acetic 
acid.  It  is  precipitated  by  hydrochloric  acid,  phosphotungstic 
acid,  and  bromin  water.  Collagen  unites  with  tannic  acid  in  the 
form  of  a  tough  and  durable  substance,  common  leather.  Gelatin 
responds  to  the  biuret  and  xanthoproteic  reactions,  but  not  to 
Millon's. 

6.  PHOSPHOPROTEINS. — Vitellin  of  egg  and  caseinogen  with  its 
derivative  casein  are    members    of   this    group.     Caseinogen,   the 
principal  protein  of  milk,  by  the  action  of  rennin,  yields  the  casein 
of  cheese.     Boiling  does  not  coagulate  it,  but  causes  it  to  split  off 
some  sulphur  and  lessens  its  digestibility.     It  contains  phosphorus, 
but  no  carbohydrate  group,  the  latter  being  supplied  to  the  suckling 
by  the  lactose  of  the  milk.      Casein  contains  phosphorus  in  direct 
combination  with  the  protein  and  not  in  a  nucleic  acid  group,  as  in 
the  nucleoproteins. 


PROTEINS  529 

II.  CONJUGATE  PROTEINS.  —  This  class  includes  the  proteins 
which  are  capable  of  being  decomposed  into  a  simple  protein  and 
some  other  substance  of  different  character.  The  non-protein  sub- 
stances yielded  by  the  splitting  give  the  character  and  name  to  the 
subclasses  in  which  they  are  grouped;  thus,  they  are  hemoglobins, 
glucoproteins,  phosphoglucoproteins,  nucleoproteins. 

a.  Chromoproteins.  —  The  typic  compound  is  the  hemoglobin, 
which  gives  color  to  the  blood  and  carries  oxygen  to  the  tissues.  In 
the  corpuscles  it  exists  as  an  insoluble  amorphous  combination, 
constituting  40  per  cent,  of  their  weight.  When  free  it  is  readily 
soluble  in  water,  insoluble  in  alcohol  and  ether,  and  crystallizable 
in  beautiful  red  crystals  which  differ  in  shape  in  the  hemoglobin 
of  different  animals.  The  form  of  combination  found  in  asphyxia 
is  called  common  or  reduced  hemoglobin;  that  in  ordinary  arterial 
blood,  richer  in  oxygen,  is  called  oxy  hemoglobin.  Owing  to  its 
remarkable  capacity  for  absorbing  gases  in  a  loose  combination 
it  is  an  easy  matter  to  convert  one  into  the  other  by  means  of  ox- 
idizing and  reducing  agents.1  The  proportion  of  the  two  hemo- 
globins in  venous  blood  is  intermediate  between  that  in  arterial 
blood  and  that  in  the  dark  blood  of  asphyxia.  The  absorption 
power  for  carbon  dioxid,  carbon  monoxid,  hydrogen  sulphid,  and 
hydrocyanic  acid  results  in  combinations  which  not  only  poison 
the  tissues,  but  also  interfere  with  the  normal  absorption  powers 
for  oxygen.  When  a  solution  of  hemoglobin  is  heated  to  70°  C. 
(158°  F.)  or  hydrolyzed,  by  acids  or  alkalis,  it  splits  into  the 
simple  protein,  globin,  and  a  colored  derivative  containing  iron, 
hematin  (pp.  527,  532). 

The  empiric  formula  for  the  hemoglobin  of  the  dog  is  — 


Hematin,  unlike  the  globin,  dissolves  in  acidified  alcohol  and 
dries  in  a  blue-black  powder  which,  with  hydrochloric  acid,  forms 
hemin  crystals  (Plate  4,  Fig.  3),  a  characteristic  test.  (See  Hem- 
aturia.) 

C32H32N4Fe04  +  HC1  —  *  C32H31ClN4FeO3  -{-  H2O. 
Hematin.  Hemin  or  chlorhematin. 

It  is  met  with  in  the  blood  and  in  the  urine  after  poisoning  from 
hydrogen  arsenid.  In  alkaline  solutions  its  spectrum  gives  a 
single,  poorly  defined  absorption  band  extending  from  C  to  D 
(Plate  4,  f  and  h). 

1  The  dissociation  that  occurs  in  the  blood  under  normal  conditions  is  represented 
as  a  reversible  process  in  this  equation: 

Oxyhemoglobin  -^*»  Hemoglobin  +  Oxygen 
34 


530 


CYCLIC    COMPOUNDS 


Spectroscopic  Tests. — The  best  method  of  distinguishing  the 
several  hemoglobins  is  by  their  absorption  spectra,  shown  in 
Plate  4. 

Oxyhemoglobin  gives  a  spectrum  which  varies  with  the  degree 
of  dilution  of  the  arterial  blood  used  for  the  observation.  The 
blood  is  opaque  when  observed  in  a  vessel  of  usual  thickness,  but 
when  diluted,  permits  more  and  more  light  to  pass  until  the  red, 
orange,  and  green  colors  appear  with  a  band  in  the  green  (Plate 
4,  b).  Further  dilution  permits  the  typic  double  band  to  appear 
to  the  right  of  the  D  line  (Plate  4,  a).  This  characteristic  spec- 
trum is  discernible  even  when  the  observation  is  made  on  a  layer, 
i  cm.  thick,  of  a  solution  o.oi  per  cent,  in  strength. 

A  change  takes  place,  to  reduced  or  common  hemoglobin,  by 
the  action  of  Stokes1  reagent  (ammoniacal  solution  of  ferrous  tar- 
trate)1  or  other  reducing  agent  (Plate  4,  c). 

Reduced  hemoglobin  shows  a  spectrum  with  a  single  broad  band 
to  the  right  of  the  D  line  (Plate  4,  c).  Agitated  with  air,  the 
solution  absorbs  oxygen  until  all  the  reduced  hemoglobin  is  con- 
verted to  oxyhemoglobin,  changing  in  color  from  purple  to  red. 

Methemoglobin  is  a  brownish,  soluble  substance  produced 
when  oxygen  is  united  with  hemoglobin  in  a  form  less  readily  separ- 
able than  in  oxyhemoglobin.  It  occurs  in  blood  that  has  decom- 
posed or  that  has  been  treated  with  various  reagents  like  amyl 
nitrite  or  potassium  ferrocyanid.  In  the  body  it  is  found  in  bloody 
transudates  and  cystic  contents;  also  in  the  blood  of  the  vessels  and 
in  the  urine  in  hematuria  following  poisonous  doses  of  antipyrin, 
phenacetin,  potassium  chlorate,  and  amyl  nitrite.  In  neutral 
fluids  its  spectrum  shows  a  band  between  C  and  D  like  that  in 
Plate  4,  g,  connected  by  shading  with  one  of  the  bands  of  Plate  4,  d. 
When  in  a  weak  solution  faintly  alkaline  with  ammonia,  as  in  stale 
urine,  the  spectrum  is  different,  the  line  between  C  and  D  moving 
to  the  right  (Plate  4,  d).  Reducing  agents  change  the  spectrum 
of  its  alkaline  solutions  to  that  of  reduced  hemoglobin  (Plate  4,  c). 

Hematoporphyrin. — When  hematin  is  treated  with  sulphuric 
acid  that  has  been  saturated  with  hydrobromic  acid,  the  iron  is 
split  off,  and  the  remainder,  iron-free,  is  a  new  dark  pigment, 
hematoporphyrin : 

C32H32N4FeO4  +  2HBr  +  2H2O  — *-  2C16H13N2O3  +  Ha  +  FeBr.2. 
Hematin.  Hematoporphyrin. 

It  is  the  cause  of  the  dark  color  of  the  blood  in  certain  diseases, 
in  intestinal  hemorrhages,  and  in  chronic  poisoning  from  sulphonal 
and  from  lead. 

1  Stokes'  reagent:  Mix  ferrous  sulphate,  3  gm.,  with  3  gm.  of  tartaric  acid 
dissolved  in  water,  and  add  water  to  100  c.c.  Before  using,  add  enough  ammonia 
water  to  dissolve  the  precipitate  and  leave  an  alkaline  reaction. 


u    (I    i; 

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.(9nriiJ  ni  '-ti  u*)o«  • ''   no*  nl>-)'i  i>jgjL..». 
.  ( cij'x^i^fn^fS^ 4^0  rnoil)  efa^a^iO  i^rDvtBmej^iij|J| 

. 

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PLATE  4. 
BLOOD-SPECTRA   AND   BLOOD-CRYSTALS. 

FIG.  1,  a.  Normal  Solar  Spectra,  with  the  various  absorp- 
tion-lines marked  by  letters  (A,  B,  C,  D,  a,  b,  a). 
The  blood  changes  the  spectrum  of  the  light  pass- 
ing through  (marked  dilution  of  the  blood  is  neces- 
sary) in  such  a  way  that,  in  accordance  with  the 
behavior  of  the  hemoglobin  present,  various  por- 
tions of  the  colored  spectrum  are  obliterated  or 
absorbed.  There  thus  appear  at  various  places 
black  bands  of  varying  thickness. 

b.  Spectrum  of  blood  rich  in  oxygen  (oxyhemoglobin- 
spectrum)  (two  bands  between  D  and  E). 

c.  Spectrum  of  reduced  hemoglobin. 

d.  Spectrum  of  methemoglobin  weak  solution,  faintly 
alkaline  with  ammonia  (accompanying   hemoglo- 
binemia,  destruction  of  the   red   blood-corpuscles 
through  poisoning  with  potassic  chlorate,  pyrogallol, 
sulfonal,  toadstools).     Without  the  alkali,  methemo- 
globin gives  in  addition  an  absorption  band  between 
C  and  D,  as  shown  in  Fig.  g. 

e.  Spectrum  of  reduced  CO-hemoglobin.     The  reduc- 
tion  accompanying   carbon-monoxid   poisoning  is 
unattended  with  disappearance  of  the  two  bands 
between  D  and  E ;  in  contrast  with  reduced  oxy- 
hemoglobin  (Fig.  c). 

f.-h.  Spectra  of  hematin  in  acid  and  alkaline  solutions 

and  reduced  (occurs  in  urine). 

FIG.  2.  Hematoidin  Crystals  (from  old  hemorrhagic  focus). 
— Partly  in  rhombic  plates,  partly  in  granules. 

FIG.  3.  Teichmann's  Hemin-crystals. — They  serve  for  the 
demonstration  of  even  slight  traces  of  blood,  old  or  recent. 
They  are  obtained  by  adding  to  the  remnant  of  blood  a  crystal 
of  sodic  chlorid  and  a  drop  of  glacial  acetic  acid,  and  effecting 
evaporation  by  gentle  heat.  Their  recognition  is  of  importance 
from  a  medico-legal  point  of  view. 

(JAKOB.) 


PLATE  4. 


PROTEINS  531 

Hematoidin  is  an  iron-free,  crystalline  solution  developed  from 
old  extravasation  of  blood.  It  is  identical  with  bilirubin  (Plate  4, 
Fig.  2). 

Carbon  monoxid  hemoglobin  is  a  stable  compound  formed  in 
the  blood  of  persons  poisoned  from  the  inhalation  of  carbon  mon- 
oxid or  illuminating  gas.  A  molecule  of  carbon  monoxid  unites 
with  a  molecule  of  hemoglobin  in  a  fixed  and  definite  compound. 
Unlike  oxyhemoglobin,  it  will  not  give  or  take  oxygen,  hence  the 
oxygen-carrying  function  is  destroyed  if  much  be  inhaled,  and 
the  victim  dies  of  asphyxia. 

The  blood  is  bright  red  and  shows  a  spectrum  with  two  bands 
almost  identical  in  position  with  those  of  oxyhemoglobin  (Plate 
4,  e).  Stokes'  reducing  fluid  does  not  change  the  carbon  mon- 
oxid spectrum,  and  the  blood,  mixed  with  an  equal  volume  of 
caustic  soda  (specific  gravity  1.3),  yields  a  bright  red  mass.  The 
mixture  of  normal  blood  with  the  alkaline  reagent  is  dirty 
brown  (p.  101). 

b.  Glucoproteins  get  their  name  from  the  fact  that  on  heating 
with  dilute  mineral  acids  they  yield  a  simple  protein  and  a  substance 
which,  like  glucose,  reduces  alkaline  cupric  solution.  They  are 
divisible  into  true  mucins,  chondroproteins,  and  mucoids. 

Mucins  occur  in  the  secretions  of  mucous  membranes  and 
mucous  glands;  also  in  connective  and  epithelial  tissues.  With 
alkaline  water  they  form  slimy  solutions  which  are  precipitated 
with  acetic  acid.  They  are  insoluble  in  excess  of  the  acid,  and 
not  coagulated  by  heat.  They  are  not  affected  by  the  gastric 
juice.  When  hydrolyzed  by  heating  with  dilute  acid  they  split 
into  acid  albuminate  and  a  carbohydrate — mucose. 

Mucoids  are  glucoproteins  found  in  intestinal  mucus,  vitreous 
humor,  white  of  egg  (ovamucoid),  and  in  the  umbilical  cord.  They 
differ  from  true  mucins  in  solubility  and  in  not  being  precipitated 
by  acetic  acid. 

Chondroproteins,  on  being  hydrolyzed  by  heating  with  dilute 
mineral  acids,  split  into  a  protein  called  chondroitin,  and  an  ester- 
sulphuric  acid  in  union  with  a  carbohydrate.  This  ester  acid, 
joined  with  nucleic  acid  and  a  protein,  constitutes  nucleo-albumin, 
a  substance  precipitated  from  some  samples  of  urine  on  the  addi- 
tion of  acetic  acid. 

The  principal  chondroproteins  are  the  chondromucoid  of  car- 
tilage, and  amyloid,  the  peculiar  substance  deposited  in  the  cap- 
illaries and  cells  of  the  kidneys,  liver,  and  spleen  as  a  result  of 
wasting  diseases,  causing  amyloid  degeneration.  Amyloid  tissues, 
like  starch,  turn  blue  on  being  treated  with  sulphuric  acid  and 
iodin.  They  color  red-brown  with  iodin  alone;  bright  red  with 
eosin;  and  red  with  anilin  green.  Amyloid  is  insoluble  in  water, 


532 


CYCLIC    COMPOUNDS 


amorphous,  white,  not  dissolved  in  gastric  juice,  and  responds  to 
the  xanthoproteic,  biuret,  and  Millon's  reaction. 

Phosphoglucoproteins  are  compound  proteins  rich  in  phos- 
phorus, which  differ  from  nucleo-albumin  and  nucleoprotein  in 
been  hydrolyzed  into  reducing  substances  with  no  xanthin  bases 
(see  p.  490). 

c.  Nucleoproteins  are  rich  in  phosphorus,  and  by  hydrolysis 
break  up  into  a  protein  and  a  true  nuclein.  Nuclein  splits  again 
into  a  protein  and  nucleic  acid,  and  the  nucleic  acid  decomposes 
into  pyrimidin  bases,  phosphoric  acid,  and  purin  bases.  Nucleo- 
histon  is  a  variety  present  in  the  thymus  gland.  Nucleoproteins  are 
necessary  to  cell  life  in  general,  especially  to  the  nucleus,  and  are 
present  in  all  the  glandular  organs,  the  spermatozoa,  pus-cells,  and 
yeast  plant.  They  are  not  dissolved  by  gastric  juice.  In  reaction 
they  are  weak  acids,  forming  soluble  salts  with  bases.  They  are 
coagulated  by  heat.  They  probably  constitute  the  chief  mass  of 
the  protein  in  cell  substance  and  are  most  important  in  relation  to 
cell  activity. 

Nucleoproteins  are  distinguished  by  the  products  obtained  after 
hydrolysis,  namely: 

True  cell  nucleins,  which  pass  from  dead  cells  into  the  animal 
fluids.  They  yield  proteins  and  nucleic  acid,  which  latter  in  turn 
splits  into  phosphoric  acid  and  purin  bases.  Gastric  digestion 
of  nucleoproteins  leaves  them  as  insoluble  residues.  As  purin 
bases  contribute  to  the  formation  of  uric  acid  (p.  490),  a  regimen 
of  food  for  patients  having  the  uric-acid  diathesis  reduces  the  meat 
allowance  to  a  minimum. 

Nucleic  acids  are  set  free  by  the  decomposition  of  nucleins  with 
alkalis.  They  break  up  into  phosphoric  acid,  pyrimidins,  and 
purins.  They  differ  in  the  bases  they  contain.  All  are  white, 
amorphous,  insoluble  in  pure  water,  acid  in  reactions,  forming 
soluble  salts  with  alkalis.  They  are  precipitated  by  acetic  acid  and 
are  found  in  the  insoluble  residue  left  when  a  nucleoprotein  is 
treated  with  gastric  juice. 

III.  DERIVATIVES  OF  PROTEINS. — Of  these,  the  products  of  protein- 
hydrolysis  by  enzyms  and  chemicals  are  those  requiring  special 
attention. 

a.  Infraproteins  are  derived  from  native  proteins  by  digestion 
with  alkalis  or  acids.  They  do  not  dissolve  in  salt  solution  nor  in 
cold  water  except  when  a  small  amount  of  acid  or  of  alkali  is 
present.  Heat  does  not  coagulate  the  solution,  but  the  albuminate 
is  precipitated  by  neutralizing  it.  Saturation  of  the  solution  with 
sodium  chlorid  or  ammonium  sulphate  causes  precipitation  from 
the  acid  solution,  but  does  not  affect  the  solution  in  alkali.  When 
the  alkalis  act  on  native  proteins  they  separate  nitrogen  and  sul- 


PROTEINS  533 

phur  from  the  molecule;  hence  an  alkali  albuminate  is  not  convert- 
ible into  an  acid  albuminate,  which  should  contain  those  elements. 
Alkalis  may  act  on  acid  albuminates  to  change  them  to  alkali 
albuminates.  An  alkali  albuminate  in  water  containing  calcium 
carbonate  dissolves  with  escape  of  carbon  dioxid.  It  has  acid 
properties  which  are  not  shared  by  acid  albuminates. 

During  gastric  digestion  the  hydrochloric  acid  changes  myosin 
of  muscle  tissue  to  syntonin,  a  form  of  acid  albuminate. 

Coagulated  proteins  are  produced  from  native  protein  by  heat, 
acids,  alcohol,  and  other  reagents,  and  by  enzyms.  Neither  the 
process  nor  the  product  is  understood.  Hard-boiled  white  of  egg 
and  fibrin  are  examples.  They  are  insoluble  in  pure  water,  in 
dilute  acids,  alkalis,  and  solutions  of  neutral  salts.  By  the  enzyms 
of  digestion  they  are  changed  to  peptones  and  albumoses.  Fibrin 
is  the  white  solid  protein  which  appears  in  clotted  blood.  A  fer- 
ment coagulates  the  dissolved  fibrinogen  of  the  plasma.  Similar 
coagulated  proteins  have  been  found  in  the  liver  and  other  glands. 

b.  Proteoses  or  Albumoses. — In  the  digestion  of  proteins  the 
final   protein-like   substance    is   called   peptone.     The   process   of 
change  is  one  of  successive  acts  of  hydrolysis — splitting  up  the 
molecule.     It  has  many  intermediate  stages,  which  are  recognized 
by  the  characteristic  proteins  derived  by  the  action  of  the  acids 
and  enzyms  of  animal  digestion.     Syntonin  or  acid  albuminate  has 
already  been  referred  to;  the  others  are  grouped  under  the  general 
head  of  proteoses,  propeptones,   or  albumoses.     All  the  proteoses 
are  soluble  in  pure  water,   non-coagulable  by  heat,   precipitated 
from  solution  by  saturation  with  ammonium  sulphate. 

The  proteoses  are  considered  under  two  classes:  primary  and 
secondary.  The  primary  includes  protoproteoses  and  heteroproteoses; 
the  former  in  its  reactions  with  neutral  salts  resemble  the  native 
albumins,  while  the  latter  are  like  the  globulins.  The  primary 
proteoses  are  precipitated  by  50  per  cent,  ammonium  sulphate  in 
acid  solution;  the  secondary  require  for  precipitation  a  saturated 
solution  of  ammonium  sulphate.  Heteroproteose  is  precipitated 
by  saturated  neutral  sodium  chlorid,  while  protoproteose  requires 
saturated  acid  sodium  chlorid. 

The  secondary  proteoses  are  derivatives  of  the  primary  varieties 
by  hydrolytic  splitting,  and  are  not  precipitated  by  cupric  sulphate. 
Having  fewer  albumin  reactions,  they  represent  further  cleavage. 
They  are  closely  related  to  the  peptones.  The  proteoses  differ 
somewhat  according  to  the  native  protein  from  which  they  are 
derived,  the  parent  substances  giving  the  name — as,  albunwse,  glob- 
ulose,  vitellose,  caseose,  etc. 

c.  Peptones. — The  last  of  the  products  of  hydrolysis  of  albumins 
that   retain   albuminous   characteristics   are   the   peptones.     They 


534 


CYCLIC    COMPOUNDS 


closely  resemble  each  other,  the  difference  being  unimportant. 
The  stages  of  hydrolysis  giving  the  cleavage  products  of  albu- 
min are  shown  in  this  scheme,  where  all  the  proteoses  (albumoses) 
are  seen  to  end  in  peptones  which  are  practically  of  one  kind: 


Primary  albumose. 
Hetero-albumose.         Protalbumose.  Syntonin. 

Secondary  albumose. 

-\^ 

Peptones. 

Polypeptids. 
Amino-acids. 

Peptones  are  very  soluble  in  water,  dialyzable,  not  coagulated  by 
heat,  not  precipitated  by  ammonium  sulphate  or  by  nitric  acid, 
with  or  without  neutral  salts.  In  common  with  other  proteins 
they  are  precipitated  by  strong  alcohol,  phosphomolybdic  acid, 
mercuric  chlorid,  and  tannin,  and  give  the  biuret  reaction. 

d.  Polypeptids.  —  Beyond  the  stage  of  peptone  in  the  cleavage 
series  given  above  are  certain  products  which  consist  of  two  or 
more  amino-acids  linked  together.  Some  of  them  give  the  biuret 
reaction.  The  majority  of  the  polypeptids  are  synthetic  products 
containing  from  2  to  7  different  amino-acids.  They  are  optically 
active,  like  the  natural  proteins,  give  the  biuret  reaction,  are  pre- 
cipitated by  phosphotungstic  acid,  and  are  split  by  trypsin  into 
the  same  hydrolytic  products  as  those  yielded  by  protein.  An 
artificial  peptid,  glyzylalanin,  has  been  made  identical  with  that 
obtained  from  natural  silk  fibrin. 

Changes  of  Proteins  in  the  Body.-—  As  saliva  contains  no  enzym 
capable  of  causing  chemical  change  in  the  proteins,  they  pass  to 
the  stomach  unaltered,  except  by  the  disintegrating  and  dissolving 
effects  of  mastication.  Both  the  soluble  and  coagulated  proteins 
need  to  be  digested  in  order  to  produce  absorbable  substances. 
These  dialyzable  products  are  the  result  of  a  series  of  hydrolytic 
reactions  by  which  the  complex  protein  is  broken  up  into  simpler 
compounds.  In  the  stomach  by  the  action  of  pepsin  and  acid 
they  change  into  acid  albumin,  proteoses  and  peptones,  successively 
increasing  in  solubility  and  diffusibility  with  each  form.  In  the 
small  intestine  the  enzym  trypsin  splits  the  protein  by  hydrolysis, 
as  does  the  pepsin,  only  more  rapidly,  and  the  medium  is  alkaline. 
The  remainder  in  the  large  intestine  undergoes  hydrolysis  by 
erepsin  and  putrefaction  by  bacteria.  The  products  of  these 


FERMENTS    OR    ENZYMS  535 

cleavages  of  the  protein  molecule  are,  successively:  proteoses,  pep- 
tones, amino-acids,  glucosamin,  hexon  bases,  cystin,  indol,  skatol, 
phenol,  and  paracresol.  The  amino-acids  and  hexon  bases,  after 
absorption,  are  synthesized  to  make  the  protein  tissue  materials. 
The  four  last-named  products,  for  the  most  part,  pass  out  with  the 
feces,  but  to  some  extent  are  absorbed  into  the  portal  blood.  Their 
poisonous  properties  are  destroyed  in  the  liver,  where  they  meet 
potassium  sulphate,  which  unites  with  them  to  form  the  conjugated 
sulphates  excreted  later  by  the  kidney.  As  potassium  sulpho- 
phenolate  and  potassium  indoxyl  sulphate,  etc.,  they  are  harmless. 
It  is  probable  that  the  absorbed  products  split  off  a  carbo- 
hydrate from  the  glucosamin,  which  is  easily  converted  to  glyco- 
gen,  dextrose,  or  even  fat. 

The  carbohydrate  and  fat  are  held  closely  to  the  protoplasm 
of  the  cells  and  are  used  by  it  as  sources  of  energy. 

The  larger  proportion  of  the  body  proteins  is  contained  in  the 
muscles.  In  them  metabolism  is  continuous,  the  massive  protein 
molecule  not  breaking  down  to  free  nitrogen,  carbon  dioxid,  and 
water,  but  chiefly  into  ammonium  salts,  lactate  and  carbamate, 
and  partly  into  glycocoll  and  other  amino-acids  with  creatin,  wrhich 
ultimately  changes  to  creatinin  and  ammonium  lactate.  All  of 
these,  on  passing  through  the  liver,  change  to  urea,  which  ultimately 
escapes  in  the  urine  (p.  492). 

The  sulphur  of  the  proteins  is  oxidized  finally  to  mineral  sul- 
phates, part  of  which  are  eliminated  by  the  kidneys  as  such  and 
part  joins  in  the  liver  to  the  aromatic  radicals,  phenol,  indol,  and 
skatol,  as  stated  above. 

Nucleoproteins  in  other  tissues  are  much  less  abundant  than 
the  muscle  proteins.  They  are  found  chiefly  in  the  gland  cells  and 
split  into  true  protein  and  nucleic  acid,  which  later  breaks  down 
into  phosphoric  acid  and  the  purin  bases.  The  latter  ultimately 
in  the  liver  oxidize  to  the  uric  acid  of  the  urine.  Thus,  the  metab- 
olism of  gland  cells  produces  uric  acid  as  regularly  as  muscle  sub- 
stance forms  urea. 

The  small  amount  of  hippuric  acid  found  in  urine  is  derived 
partly  from  food  and  partly  from  the  oxidation  of  aromatic  groups 
of  protein  metabolism  into  benzoic  acid.  In  the  kidney  the  benzoic 
acid  is  joined  with  glycocoll  to  form  hippuric  acid,  and  is  then 
excreted. 

FERMENTS  OR  ENZYMS 

Fermentation  is  the  transformation  of  an  organic  substance 
produced  by  an  enzym  acting  by  catalysis  (p.  395).  The  enzym 
is  secreted  in  the  living  body  by  cell  action  or  is  produced  by  the 
processes  of  nutrition  of  low  organisms.  At  one  time  these  organ- 


536  CYCLIC   COMPOUNDS 

isms — bacteria,  molds,  etc. — were  called  the  true  ferments,  and 
their  soluble  enzyms  called  false  ferments;  but  it  is  now  established 
that  the  living  molds  act  because  they  contain  the  ferment,  and 
the  true  agent  in  every  case  is  the  soluble  enzym.  Moreover,  this 
product  of  cell  life  can  manifest  its  special  activity  after  the  death 
of  the  parent  cell.  As  yet  the  enzyms  have  not  been  isolated  in 
a  chemically  pure  form.  They  are  commonly  regarded  as  albu- 
minous, but  this  may  be  only  an  appearance  due  to  the  adherent 
particles  of  protein  matter.  They  are  soluble  in  water,  yet  are 
not  diffusible,  and  are  precipitated  by  ammonium  sulphate  or 
strong  alcohol.  It  is  probable  that  some  of  them  are  collodial 
combinations  of  organic  substances  with  metal  ions,  such  as  man- 
ganese and  iron.  They  are  identified  by  their  end  products. 

Enzyms  are  very  susceptible  to  certain  external  influences.  Al- 
though they  resist  dilute  solutions  of  poisons,  such  as  chloroform, 
thymol,  salicylic  acid,  arsenous  acid,  boric  acid,  and  glycerin, 
they  are  paralyzed  by  HgCl2,HCN,  carbolic  acid,  and  sulphites. 
Their  action  is  arrested  by  absence  of  water,  to  be  restored  when 
moisture  is  abundant.  As  a  general  rule,  the  animal  ferments, 
when  moist,  are  killed  by  a  temperature  of  75°  C.  (167°  F.),  and 
the  vegetable  ferments  by  80°  C.  (176°  F.).  When  dry  they  may 
withstand  a  temperature  of  150°  C.  (302°  F.).  All  are  destroyed 
by  boiling  and  by  any  but  weak  concentrations  of  acids  and  alkalis. 
They  are  most  active  at  the  temperature  of  the  animal  body.  An 
enzym  selects  specifically  the  substance  upon  which  it  works. 
Thus,  one  decomposes  a  certain  sugar  of  an  isomeric  group,  but 
does  not  affect  the  others,  almost  identical.  This  enzym  must 
have  a  stereochemical  structure  related  to  the  stereochemical  struc- 
ture of  the  sugar,  as  a  key  fits  into  a  lock. 

The  functions  of  the  enzyms  are  specific  and  well  understood. 
In  most  cases  they  hydrolyze,  i.  e.,  cause  a  reaction  with  water,  ending 
in  cleavage  of  the  substance  upon  which  they  act.  In  other  cases 
they  are  concerned  with  the  oxidations  of  the  tissues.  In  some 
way  they  communicate  such  disturbances  to  the  complex  albumin- 
ous or  polysaccharid  molecules  as  to  lead  to  simpler  and  more 
stable  combinations.  In  this  they  act  like  the  catalyzing  colloidal 
solutions  of  metals,  which  accelerate  certain  reactions  (p.  87).  In 
all  cases  the  amount  of  transformation  is  out  of  proportion  to 
the  quantity  of  the  agent,  and  the  agent  is  not  used  up,  as  it  takes 
no  part  in  the  reaction.  Colloidal  platinum  breaks  up  1,000,000 
times  its  quantity  of  hydrogen  peroxid  and  remains  as  strong  as 
ever.  It  also  inverts  cane-sugar,  like  invertase,  and  acts  on  certain 
fats  like  a  fat-splitting  enzym.  The  poisons  which  inhibit  the 
ferments,  such  as  mercuric  chlorid  and  hydrocyanic  acid,  also 
paralyze  the  catalytic  action  of  colloidal  platinum. 


FERMENTS    OR    ENZYMS  537 

Ferment  action  is  not  only  one  of  decomposition,  but  also  may 
at  times  be  one  of  construction.  Maltose  is  not  completely  changed 
by  its  ferment  into  glucose,  but  only  up  to  a  point  of  equilibrium. 
Using  concentrated  solutions  of  pure  glucose,  the  same  ferment 
reverses  its  action  and  builds  up  maltose  to  the  same  point  of  natural 
equilibrium  between  the  fermented  substance  and  its  products. 
The  fat-splitting  lipase  causes  not  only  the  hydrolysis  of  ethyl 
butyrate  into  alcohol  and  butyric  acid,  but,  with  a  change  in  the 
acting  masses,  also  the  reverse  synthesis  of  alcohol  and  acid  into 
the  ester.  Thus  the  same  enzym  may  split  or  may  build  up  fats 
according  to  the  concentrations  present.  Fat  is  digested  by  steap- 
sin  in  the  intestine  only  when  the  resulting  glycerin  and  fatty  acids 
are  removed  as  they  are  formed.  In  the  fluids  of  the  tissues,  on 
the  other  hand,  the  glycerin  and  acids  are  in  excess,  the  activity  of 
the  enzym  is  reversed,  and  fat  is  deposited.  During  starvation  the 
lipase  acts  directly  on  the  fat  deposits  and  the  fatty  acids  and 
glycerin  of  the  cells  diffuse  into  the  blood.  From  this  it  appears 
that  the  intracellular  enzyms  not  only  break  down  and  clear  away 
effete  matter,  but  act  synthetically  and  probably  maintain  the 
normal  equilibrium  between  the  cell  contents  and  the  serum  of 
blood  or  lymph  (p.  83). 

It  is  now  established  that  enzyms  are  omnipresent  in  the  cells 
and  take  part  in  almost  all  chemical  changes  in  the  living  body. 
The  liver-cells  alone  exhibit  such  varied  catalytic  powers  that  we 
must  assume  the  presence  in  them  of  twenty  different  enzyms. 
Only  the  principal  groups  concerned  in  digestion,  nutrition,  and 
secretion  are  referred  to  in  the  list  on  p.  538. 

Nomenclature. — In  order  to  simplify  the  nomenclature,  it  is 
proposed  to  attach  the  suffix  -ase  to  the  stem  of  the  name  of  the 
substance  upon  which  it  acts;  thus,  saccharase  is  the  specific  enzym 
of  saccharose. 

Classification. — A  good  basis  for  grouping  the  ferments  is 
found  in  their  specific  functions  and  the  products  of  their  action. 
Four  classes  of  great  interest  are  those  which  hydrolyze  the  food- 
stuffs, proteins,  carbohydrates,  and  fats.  In  the  following  arrange- 
ment they  are  mentioned  first: 

Proteases  (Proteolytic  Enzyms}. — Pepsin  of  the  stomach  and 
trypsin  of  the  pancreas  are  digestive  ferments  which  break  up  the 
complex  non-dialyzable  protein  molecules  into  proteoses  and  pep- 
tones. Erepsin,  which  is  found  in  the  intestinal  mucus,  hydro- 
lyzes  proteoses  to  amino-acids.  The  power  of  self-digestion, 
shown  by  the  antiseptic  tissues  after  death,  is  due  to  autolytic  pro- 
teases (pp.  523  and  545). 

Amylases  (Amylolytic  Enzyms). — Ptyalin  of  the  saliva,  the 
diastases  of  the  pancreas,  of  the  liver,  and  of  vegetables,  hydro- 


538  CYCLIC    COMPOUNDS 

lyze  the  starch  molecule  and  split  it  into  a  disaccharid  maltose, 
with  dextrin  as  an  intermediate  product  (pp.  543  and  556). 

Invertases  (InvertingEnzyms). — In  the  saliva,  in  the  pancreatic, 
and  in  enteric  juices  ferments  are  found  which  invert  the  disacch- 
arids  to  monosaccharids,  saccharase  acting  on  cane-sugar,  maltase 
on  maltose,  lactase  on  lactose  (p.  557). 

Lipases  (Lipolytic  Enzyms). — The  hydrolysis  of  fats  to  fatty 
acids  and  glycerin  is  accomplished  by  the  steapsin  of  the  pancreas 
and  also  by  lipases  in  the  gastric  juice  and  the  tissues  generally 
as  intracellular  enzyms  (pp.  545  and  557). 

Urases  are  enzyms  that  hydrolyze  urea  into  ammonium  car- 
bonate. They  are  secreted  by  various  bacteria  that  excite  am- 
moniacal  fermentation  in  stale  urine  (p.  585). 

Nucleases  are  enzyms  in  the  tissues  which  split  nucleic  acid 
into  phosphoric  acid  and  the  purin  bases  (p.  492). 

Next  in  point  of  interest  come  the  enzyms,  the  special  action 
of  which  is  to  oxidize  albuminous  substances  in  the  cells. 

Oxidases  (Oxidizing  Enzyms). — The  oxygen  carriers  are  di- 
vided into  three  groups,  two  of  which,  oxygenases  and  perox- 
idases,  yield  oxygen  to  other  substances  and  then  immediately 
reoxidize  themselves.  The  third,  catalases,  cannot  reoxidize 
themselves  from  the  air. 

Oxygenases  turn  tincture  guaiac  blue  by  direct  transference  of 
the  molecular  oxygen  of  the  air. 

Peroxidases  are  bodies  which  contain  manganese,  aluminium, 
iron,  and  possibly  copper.  They  are  quite  stable  and  do  not  ox- 
idize directly,  but  only  in  the  presence  of  peroxids.  Only  on  the 
addition  of  hydrogen  peroxid  will  they  turn  guaiac  blue. 

Catalases  are  the  agents  in  protoplasm  which  decompose  hy- 
drogen peroxid  so  that  the  peroxidases  can  utilize  the  liberated 
oxygen.  They  do  not  turn  guaiac  blue  directly  nor  in  the  pres- 
ence of  hydrogen  peroxid. 

Guaiac  Test  jor  Oxidases. — Make  a  fresh  tincture  of  guaiac  by 
boiling  pieces  of  guaiac  with  alcohol  in  a  test-tube.  When  a  deep 
yellow  color  is  developed,  filter  and  add  a  few  drops  of  the  filtrate 
to  water  until  a  milky  emulsion  is  formed.  A  slice  of  raw  potato 
indicates  the  presence  of  oxygenases  by  turning  the  emulsion  blue. 
If,  instead  of  potato,  some  blood  or  raw  meat,  minced,  containing 
peroxidases  be  immersed  in  the  emulsion,  there  is  no  change  until 
hydrogen  peroxid  is  added,  when  the  blue  reaction  appears.  If 
bubbles  of  free  oxygen  form  on  the  tissue  after  the  peroxid  is  added, 
catalases  are  present. 

Coagulases  (Clotting  Enzyms). — These  comprise  thrombase, 
which  coagulates  the  fibrin  of  the  blood;  and  rennin,  which  curdles 
milk.  As  calcium  salts  are  necessary  for  their  action,  it  is  probable 


ENERGY    OF    FOODS  539 

that  the  clot  is  a  calcium  compound  of  fibrin  or  casein  (pp.  545  and 
562). 

Having  a  very  different  chemical  effect  are: 

Reductases  (reducing  enzyms),  such  as  the  one  that  reduces 
sulphur  to  hydrogen  sulphid. 

Glue os id- splitting  enzyms  play  an  important  part  in  certain 
medicinal  plants.  Mention  has  been  made  (pp.  443  and  464) 
of  the  action  of  emulsin  or  synaptase  upon  amygdalin.  Another 
example  is  the  action  of  myrosin  upon  the  sinigrin  (myronic  acid) 
of  mustard  seed,  which  develops  allyl  mustard  oil. 

On  the  other  hand,  synthesis  of  amygdalin  can  be  brought  about 
by  the  enzym  maltase  acting  upon  mandelic  nitrile  and  glucose: 

C14H17N06     +      C6H1206     -      C20H27NOn     +     H2O. 

Mandelic  nitrile.  Amygdalin. 

Bacteriolytic  enzyms  split  up  their  media  by  secretion  of  bacilli, 
such  as  those  of  lactic  and  butyric  acids  (pp.  419,  444). 

Autolytic  enzyms  are  found  in  the  tissues  generally.  They  are 
supposed  to  split  proteins  into  nitrogenous  bases,  such  as  the  purins 
(pp.  490-494).  Guanase,  of  the  thymus  gland,  adrenals,  and 
pancreas,  converts  guanin  to  xanthin.  Adenase,  of  the  spleen,  liver, 
and  pancreas,  converts  adenin  to  hypoxanthin.  The  breaking-up 
process  continues  in  the  liver  and  spleen  until  uric  acid  is  produced, 
and  this  itself  is  destroyed  by  enzyms.  These  uricolytic  enzyms 
have  been  found  in  the  liver,  kidney,  muscles,  and  bone-marrow. 
The  uric  acid  is  split  by  them  to  glycocoll,  allantoin,  and  oxalic  acid. 

Normal  milk  has  enzyms  favorable  to  the  digestion  of  the  milk 
(p.  567).  Alcoholic  and  acetous  enzyms  are  described  on  pp.  419,  444. 


ENERGY  OF  FOODS 

IN  the  preceding  pages  we  have  studied  the  properties  of  foods 
and  of  the  proximate  principles  of  the  human  body,  and  stated 
briefly  the  chemical  changes  they  undergo  while  subject  to  the  proc- 
esses of  life.  These  changes  in  the  principles  of  the  organism  are 
incessant.  It  is  necessary  to  life  that  the  elementary  atoms  should 
not  remain  in  stable  groups,  but  forever  be  moving  from  one 
unstable  organic  form  to  another.  In  another  place  (p.  109)  it  has 
been  stated  that  matter  is  indestructible,  and  that  the  forces  which 
move  matter  are  phases  of  one  energy,  the  total  of  which  is  not 
diminished  or  increased.  The  union  of  carbon  and  oxygen  converts 
the  chemical  energy  of  the  two  separate  elements  into  the  measurable 


540  FOODS    AND   DIGESTION 

free  energy  of  heat.  Energy  under  appropriate  conditions  takes 
the  different  forms  of  light,  electricity,  magnetism,  mechanical 
motion,  or,  in  the  animal  body,  the  collection  of  forces  that  con- 
stitutes life. 

From  the  energies  of  the  sunbeam  the  leaf  of  the  plant  derives 
power  to  decompose  carbon  dioxid.  From  the  earth,  by  its  rootlets, 
the  plant  obtains  water,  nitrates,  and  other  mineral  salts.  The 
sunbeams  supply  energy  for  the  synthesis  of  these  simple  sub- 
stances into  the  complex  molecules  of  starch,  sugar,  glutin,  oils, 
etc.  These  food  principles  are  stores  of  potential  energy  for  the 
animal,  which  reverses  the  chemical  processes,  liberating  the  energy 
in  active  forms  as  the  proteins  and  carbohydrates  break  up  into 
urea,  carbon  dioxid,  and  water.  These  animal  excreta  in  turn  be- 
come food  for  plants  (p.  104).  The  organic  food  materials  which 
animals  take  from  plants  are  not  assimilable  in  their  original  state. 
After  they  are  eaten  they  must  be  altered  chemically  before  they 
are  suitable  for  absorption.  Digestion  is  the  sum  of  the  chemical 
processes  preliminary  to  absorption.  Metabolism  includes  the 
processes  of  nutrition  and  secretion  taking  place  after  absorption 
in  the  fluids  and  cells  of  the  tissues.  They  are  partly  constructive 
(anabolic)  of  digested  products  into  protoplasm,  and  partly  destruc- 
tive (katabolic)  of  protoplasm  into  excrementitious  substances. 
Metabolism  may  be  regarded  as  the  efforts  of  the  enzyms  to  main- 
tain an  equilibrium  in  cell  substance  which  must  be  continuously 
readjusted  because  of  the  loss  of  balance  due  to  oxidation  or  other 
changes  in  the  components  of  cells. 

Foods. — The  substances  actually  needed  by  the  body  to  maintain 
physical  and  mental  strength,  health,  weight,  endurance,  and  re- 
sistance to  disease  are  called  foods. 

These  must  be  supplied  not  simply  in  the  minimum  amount 
and  proportion  to  keep  an  equilibrium  between  waste  and  repair, 
but  with  an  additional  allowance  to  provide  against  the  danger  of 
under-nutrition  when  unusual  stress  occurs.  An  undue  supply 
above  the  correct  requirements  may  prove  not  only  wasteful,  but 
even  injurious,  by  the  unnecessary  tax  put  upon  the  katabolic  proc- 
esses and  the  eliminating  organs.  The  various  kinds  of  food-stuffs 
used  by  man  have  constituents  that  can  be  arranged  in  four  groups, 
viz.:  (i)  Proteins  or  albuminous  substances;  (2)  carbohydrates 
(sugar,  starch,  etc.);  (3)  fats;  (4)  inorganic  salts. 

Proteins  or  Nitrogenous  Foods. — From  both  vegetable  and 
animal  sources  we  obtain  albuminous  substances  essential  to  life, 
containing,  when  dry,  nitrogen,  about  16  per  cent.  They  are 
abundant  in  bread,  cereals,  peas,  beans,  fish,  eggs,  and  meat.  The 
two  last-named,  eggs  and  lean  meat,  are  almost  entirely  protein. 
Bread  and  cereals  are  composed  mostly  of  the  carbohydrate  starch, 


ENERGY    OF    FOODS  541 

but  all  have  some  protein.  Flour  has  13.5  per  cent,  protein  and 
fresh  green  peas  7  per  cent.  The  destiny  of  protein  is  to  be  oxi- 
dized for  the  most  part  to  urea,  carbon  dioxid,  and  water.  Urea 
is  not  a  final  oxidation  product,  and  hence  contains  some  energy 
not  fully  utilized  in  the  body.  The  food  value  of  proteins  is,  there- 
fore, not  perfectly  expressed  in  terms  of  complete  oxidation,  like 
that  of  the  carbohydrates,  but  in  terms  of  nitrogen  content  in 
addition  to  juel  value. 

Carbohydrates. — The  foods  of  this  class  contain  no  nitrogen,  but 
belong  to  the  family  of  saccharids  (p.  434).  They  are  the  sugars 
and  starches  derived  mainly  from  plants,  and  either  eaten  pure 
after  separation  or  taken  with  the  other  constituents  of  the  vegetable. 
Eaten  in  the  dry  state,  these  foods  are  almost  wholly  carbohydrates, 
rice  being  79  per  cent,  starch  and  8  per  cent,  proteins.  Allowing 
78  per  cent,  for  water  in  the  raw  potato,  18.5  per  cent,  is  starch 
and  2.2  per  cent,  protein. 

Fats. — Derived  from  both  plants  and  animals  are  olive  and 
cotton-seed  oil,  butter,  bacon,  and  tissue  fats  made  up  of  the  non- 
nitrogenous  compounds,  stearin,  palmitin,  olein,  and  other  fats. 
Being  rich  in  carbon,  they  are  very  combustible,  and  liberate  a 
large  amount  of  heat  when  oxidized. 

Inorganic  Salts. — The  mineral  phosphates,  chlorids,  carbonates, 
and  sulphates  are  necessary  for  the  various  secretions  and  pro- 
motion of  tissue  changes,  but  in  great  part  they  circulate  in  and 
pass  out  of  the  body  without  much  change. 

Energy  Value  of  Food. — Excepting  the  inorganic  salts,  all  the 
food-stuffs  are  combustible.  By  burning  them  with  oxygen  in  a 
calorimeter  the  units  of  heat  set  free  can  be  determined  and  used 
as  an  equivalent  of  nutritive  potency.  It  has  been  stated  (p.  34) 
that  i  gm.  of  a  carbohydrate  yields  4100  small  calories  or  4.1  Cal. 
(p.  73).  The  same  heat  value  is  shown  by  i  gm.  of  protein.  One 
gram  of  fat  gives  a  much  larger  amount,  viz. :  9300  small  calories 
or  9.3  Cal. 

Fats  and  carbohydrates  serve  best  as  sources  of  ordinary  work- 
ing energy,  but  to  replace  the  substance  of  tissue  wasted  at  least  an 
equivalent  amount  of  protein  is  required  in  the  food.  The  oxi- 
dation products  of  the  fats  and  carbohydrates  are  the  easily  elimi- 
nated water  and  carbon  dioxid.  On  the  other  hand,  the  metabolism 
of  nitrogenous  substances  is  attended  by  the  formation  of  purin 
bases,  uric  acid,  and  other  compounds  intermediate  between  protein 
and  its  final  excrementitious  form,  urea.  These  substances  above 
a  normal  or  average  mean  for  the  individual  are  not  readily  elimi- 
nated, and  when  retained  may  be  the  cause  of  mischief  more  or  less 
serious.  They  are  especially  hurtful  when  the  excretory  organs, 
such  as  the  kidneys,  fail  to  do  their  share  of  the  work  of  removing 


542 


FOODS    AND    DIGESTION 


effete  matter.  It  is  of  prime  importance  to  know,  on  the  one  hand, 
how  much  food  is  usually  consumed  to  satisfy  the  natural  craving 
in  a  liberal  manner  and,  on  the  other  hand,  how  little  is  actually 
required  for  the  needs  of  the  body  under  ordinary  conditions  in 
the  service  of  health,  but  not  of  luxury. 

Dietary  Standards. — Analysis  of  the  diet  of  laborers  and 
soldiers  of  different  nationalities  has  shown  that  the  average  daily 
consumption  provides  for  a  total  fuel  value  of  over  3000  Cal. 
The  protein  average  is  about  120  gm.,  containing  19  gm.  of  nitrogen. 
The  American  professional  man  or  sedentary  person  with  moderate 
work  usually  takes  100  gm.  of  protein  with  fats  and  carbohydrates, 
giving  energy  equivalent  to  2700  Cal.  The  researches  of  Chittenden 
upon  the  diet  of  professors,  athletes,  and  soldiers,  when  not  taxed  by 
excessive  physical  or  nervous  strains,  show  conclusively  that  the 
customary  dietaries  are  in  excess  of  the  indispensable  minimum 
and,  therefore,  in  the  long  run  might  prove  objectionable  in  a  case 
of  inadequate  action  of  the  excretory  organs,  even  if  the  economic 
aspects  be  ignored.  He  found  that  professional  men  living  regular 
and  care-free  lives  can  maintain  a  state  of  nitrogen  equiiibrium 
with  a  daily  diet  containing  50  gm.  of  protein  and  an  additional 
amount  of  carbohydrate  and  fat  yielding  a  total  energy  value  of 
about  2000  Cal.  Vigorous  health  of  mind  and  body  continued  for 
months  on  this  diet,  containing  one-half  the  amount  of  protein  and 
two-thirds  the  calorific  power  of  the  standards  in  use.  Athletes 
free  from  anxieties,  but  making  heavy  demands  for  muscular  work, 
were  in  healthy  equilibrium  on  a  daily  diet  of  56  gm.  of  protein 
and  a  total  fuel  value  of  about  2500  Cal.  The  evidence  goes  to 
show  that  all  the  actual  needs  of  the  human  body  under  the  regular 
conditions  of  a  "simple  life"  can  be  served  on  a  diet  containing 
much  less  nitrogen  than  is  customary  in  the  habits  and  standards 
of  mankind.  The  best  dietary  is  one  in  which  the  vegetable  foods 
predominate  and  the  heavier  meats  are  taken  in  moderation. 


DIGESTION 

Mastication. — Digestion  begins  with  the  mechanical  disin- 
tegration of  the  food  in  the  mouth  by  chewing,  where  at  the  same 
time  it  is  mixed  with  saliva.  The  mass  is  thus  softened,  moistened, 
partly  dissolved,  and  made  ready  for  its  propulsion  into  the  stom- 
ach. The  mixed  secretions  of  the  mouth,  called  saliva,  contain 
enzyms  which  hydrolyze  starch  and  split  it  into  soluble  starch, 
dextrin,  maltose,  and  glucose. 


SALIVA  543 

SALIVA 

This  fluid  is  a  mixture  of  the  secretions  of  the  parotid,  sub- 
maxillary,  sublingual,  and  buccal  glands.  It  is  tasteless,  colorless, 
odorless,  viscid,  and  frothy.  It  is  opalescent  and  turbid  from  the 
floating  particles  of  food,  epithelium,  and  mucous  cells.  The  flow 
is  continuous,  but  variable,  rising  in  amount  by  the  reflex  stimulus 
of  chewing  and  by  the  smell  and  sight  of  food.  The  average  daily 
quantity  is  from  600  to  1500  c.c.  (20-50  fl.  oz.).  Its  reaction  is 
faintly  alkaline,  though  sometimes  slightly  acid  after  eating;  its 
specific  gravity,  1002  to  1008;  the  proportion  of  dissolved  solids, 
5  to  10  parts  per  thousand. 

In  100  parts  there  are:  water,  99.42;  mucin  and  epithelium, 
0.22;  fats,  o.n;  albumin  and  the  two  enzyms,  ptyalin  and  maltase, 
0.12;  salts,  0.13. 

The  salts  include  potassium  thiocyanate  (sulphocyanid),  be- 
sides the  alkaline  and  earthy  chlorids,  phosphates,  and  carbonates. 
The  digestive  power  of  the  saliva  is  in  proportion  to  the  quantity 
of  the  enzyms.  The  ptyalin  converts  cooked  starch,  through  the 
intermediate  stages  of  soluble  starch,  dextrin,  and  erythrodextrin, 
into  maltose  and  isomaltose  (p.  441): 

io(C6H1005)n     +      4(H20)n     = 

Starch.  Water. 

4(C12H22Ou)n     +      (C6H1005)n     +      (C6H1005)n 

Maltose.  Achroodextrin.  Erythrodextrin. 

The  other  enzym,  maltase,  is  in  smaller  quantity,  and  converts 
maltose  into  glucose  (p.  438).  Slightly  acid  or  neutral  solutions 
are  best  suited  to  the  action  of  these  starch-splitting  ferments. 
While  they  have  some  activity  in  the  weak  carbon  acids,  this  power 
is  lost  when  the  acidity  in  free  HC1  reaches  that  of  the  gastric  juice. 
The  free  acid  in  the  active  pyloric  end,  some  time  after  deglutition, 
destroys  the  ptyalin,  but  the  salivary  fermentation  continues  first 
for  a  considerable  period  in  the  gastric  fundus,  which  may  be  neu- 
tral in  reaction  or  weakly  acid  from  acid  protein. 

Fermenting  Power. — By  chewing  paraffin,  a  bit  of  rubber,  or 
glass  rod,  saliva  is  made  to  flow,  and  collected  by  spitting  into  a 
beaker  until  50  c.c.  are  collected. 

Experiment  i. — Having  labeled  two  test-tubes  A  and  B,  place 
in  A  starch  paste  and  saliva,  tut  in  B  some  saliva,  dilute  and 
boil  it,  then  add  starch  solution  and  stand  both  in  a  water-bath 
for  ten  minutes;  meanwhile  go  on  with  experiments  5,  6,  7,  and  8. 

Experiment  2. — At  the  end  of  ten  minutes  pour  half  the  con- 
tents of  A  into  a  test-tube  containing  a  drop  of  HC1  and  a  few 
drops  of  iodin  solution.  If  a  purple  color  develop,  then  starch 
and  dextrin  are  present;  if  the  color  is  reddish  brown,  erythro- 


544  FOODS    AND    DIGESTION 

dextrin  and  no  longer  starch;  absence  of  all  color  indicates  absence 
of  both  erythrodextrin  and  starch.. 

Experiment  3. — If  the  remaining  half  of  A  is  added  to  boiling 
Fehling's  solution  and  a  red  precipitate  falls,  a  mixture  of  maltose 
and  glucose  is  present  as  the  result  of  fermentation  due  to  ptyalin 
and  glucose. 

Experiment  4. — The  contents  of  tube  B,  when  treated  by  tests 
2  and  3,  show  a  blue  color  with  iodin  and  no  red  precipitate  with 
Fehling's  solution.  This  denotes  that  boiling  the  saliva  has  de- 
stroyed its  power  of  digestion  and  the  starch  is  unchanged. 

Chemical  Properties.— While  waiting  for  the  fermentation 
tests,  a  further  flow  of  saliva  may  be  caused  and  the  reaction 
taken  with  litmus  paper. 

Experiment  5. — On  addition  of  acetic  acid  to  dilute  saliva  a 
precipitate  shows  mucin. 

Experiment  6. — Boiling  with  strong  nitric  acid  gives  a  yellow 
color,  which  deepens  if  ammonia  be  added.  This  denotes  a  protein. 

Experiment  7. — A  drop  of  nitric  acid  and  silver  nitrate  shows 
the  chlorids  by  a  white  precipitate. 

Experiment  8. — Ferric  chlorid  turns  the  saliva  red  from  the 
presence  of  a  sulphocyanate  with  a  trace  of  hydrochloric  acid. 

GASTRIC  CONTENTS 

Gastric  Juice. — When  food  enters  the  stomach,  or  is  merely 
presented  to  the  senses,  or  well  chewed  before  swallowing,  there 
is  secreted  a  fluid  called  the  gastric  juice.  If  free  from  food 
particles,  it  is  thin,  clear,  or  faintly  cloudy,  pale  yellow,  with  a 
strongly  acid  reaction  and  a  specific  gravity  of  1001  to  1010.  In 
a  day  the  amount  poured  out  will  vary  between  4  and  10  pt.,  part 
of  which  is  absorbed  with  the  digested  product  while  fresh  portions 
are  being  secreted.  By  reflex  action  the  production  of  gastric 
juice  is  strongly  stimulated  by  the  taste  of  food  or  bitter  substances 
in  the  mouth.  The  juice  which  is  secreted  by  psychic  or  "appetite' ' 
stimulus  is  most  important,  inaugurating  gastric  digestion,  the 
first  products  of  which,  when  absorbed,  in  their  turn  stimulate 
secretion  by  a  reflex  circuit  including  excitable  nerve-endings  in 
the  mucous  membrane  of  the  stomach.  To  excite  the  secretion  of 
this  psychic  juice,  eating  must  be  done  with  attention  and  relish. 
Water  alone  introduced  into  the  stomach  will  cause  some  flow,  but 
food  will  increase  it  greatly.  A  free  secretion  does  not  take  place 
until  there  has  been  some  absorption;  hence  the  advantage  of 
having  soup  as  the  first  course  of  a  meal.  When  pure  and  free 
from  residues  of  food,  the  acid  reaction  is  chiefly,  if  not  wholly, 
due  to  hydrochloric  acid,  about  0.2  or  0.3  part  per  cent.  Immedi- 
ately after  feeding,  especially  if  the  meal  be  rich  in  carbohydrates, 
lactic  acid  appears  abundantly.  The  protein  material  contained 


GASTRIC    CONTENTS 


545 


in  fresh  gastric  juice  is  due  to  a  little  mucin  and  two  enzyms,  pepsin 
and  rennin. 

Average  composition  of  gastric  juice.  Per  cent. 

Water 99-44 

Solids,  as  tabulated  below 0.56 

Organic  substances  (pepsin  and  peptones) 0.32 

Free  hydrochloric  acid 0.25 

Sodium,  potassium,  and  calcium  chlorids 0.21 

Calcium,  magnesium,  and  ferric  phosphates 0.02 

Pepsin. — A  characteristic  property  of  the  pepsin  is  its  power  of 
converting  proteins  into  dissolved  proteoses  and  peptones  in  an 
acid,  but  not  in  a  neutral  or  alkaline  medium.  The  protein  swells 
and  clears  up  before  it  dissolves.  The  albumin  of  hard-boiled  egg 
cut  into  disks  i  mm.  thick  is  not  altered  by  dilute  hydrochloric 
acid  when  immersed  in  it  for  several  hours  at  the  temperature  of 
the  body.  If,  however,  pepsin  has  been  present,  the  edges  become 
clear,  transparent,  and  swollen,  and  the  albumin  dissolves.  On 
the  other  hand,  pepsin  alone  has  no  action  on  proteins,  the  acid, 
too,  being  essential  (see  p.  554). 

Pepsinum,  U.  S.  P.,  is  the  enzym  as  obtained  from  the  glandular 
layer  of  the  fresh  stomach  of  the  hog.  It  occurs  in  yellowish  white 
scales  or  powder,  having  a  slightly  acid  taste.  It  is  soluble  in  50 
parts  of  water;  more  soluble  in  water  acidulated  with  hydrochloric 
acid.  If  that  acid  is  present  in  greater  strength  than  0.5  per  cent., 
the  proteolytic  activity  is  checked  and  destroyed.  It  is  incom- 
patible with  pancreatin,  destroying  it  if  the  mixture  be  acid;  if  the 
solution  be  neutral  or  alkaline,  the  pancreatin  destroys  the  pepsin. 

Rennin,  or  chymosin,  is  the  enzym  which  is  characterized  by 
coagulating  the  casein  of  milk.  It  may  be  absent  in  carcinoma, 
•chronic  catarrh,  and  atrophy  of  the  membrane  of  the  stomach. 

Chyme  is  the  pulpy  mass  into  which  the  food  is  converted  in 
the  stomach  by  the  action  of  the  gastric  juice  and  saliva.  It  is 
acid  in  reaction  and  contains  the  transformation  products  of  di- 
gestion of  carbohydrates  and  proteins,  mixed  with  much-changed 
but  undigested  matter  which  remains  to  be  digested  in  the  intes- 
tines. The  albuminous  foods  are  prepared  in  the  stomach  for 
a  final  digestive  process  of  the  intestines. 

A  swollen  and  slippery  change  marks  partial  digestion  of  meat, 
muscle,  and  cartilage.  The  combination  of  pepsin  and  rennin 
curdles  milk  either  in  large  lumps  of  cheese  or  smaller  flocculi 
distributed  through  the  mass.  Bread  is  pulpified,  though  other 
vegetable  foods,  such  as  potatoes,  may  be  found  in  distinct  morsels. 
Part  of  the  starch  taken  is  converted  into  dextrin  and  sugar  while 
digesting  in  the  quiet  fundus. 

It  is  probable  that  the  fundus  secretes  a  lipase  capable  of 
splitting  emulsified  fat. 

35 


546 


FOODS    AND    DIGESTION 


CLINICAL  EXAMINATION 


The  scope  of  this  section  does  not  include  all  the  physiologic 
and  pathologic  relations  of  the  stomach  contents,  but  only  such 
as  have  clinical  value.  The  range  of  the  casual  examination  may 
be  summarized  in  the  following  procedures,  which  are  enlarged 
upon  later  on: 

Filter  the  gastric  contents  and  use  the  nitrate, 
„  (A)  Test  acidity  with  litmus  paper;  it  may  be  normal,  super- 
acid,  subacid,  anacid. 

(B)  Find   the   acid   when   not   combined.     For   free   acid   use 
Congo  red,  or  tropeolin  oo.      To  tell  the  kind  of  acid:    For    hy- 
drochloric acid  use  Topfer's  reagent,  which  shows  0.02  per  1000; 
or   Gtinzburg's  reagent,   which  is  delicate   for  0.05  per  1000;   or 
Boas'  reagent,  which  has  the  same  delicacy  as  Giinzburg's  (p.  549). 

For  lactic  acid  use  Uffelmann's  reagent,  which  is  delicate  for 
o.i  per  1000  (p.  552). 

(C)  Determine  total  acidity:  Titrate  10  c.c.  of  nitrate  to  which 
has  been  added  phenolphthalein  (i  per  cent,  alcoholic  solution),  4 
drops,  with  a  decinormal  solution  of  caustic  soda  (4  gm.  to  i  L.)— 

1  c.c.  of  this  solution  =  0.003646  gm.  of  HC1  or  0.009  gm.  of  lactic 
acid. 

Hydrochloric  acid  is  normal  at  end  of  first  hour  in  parts  1.5  to 

2  per  1000  (0.15  to  0.2  per  cent.);  or  at  end  of  third  or  fourth  hour 
in  parts  2.3  to  3  per  1000  (0.23  to  0.3  per  cent.). 

Gross  inspection  of  vomited  matters  or  stomach  contents  con- 
sists in  noting  the  presence  or  absence  of — (i)  food  particles  and 
whether  fresh  or  old;  also  the  progress  of  digestion.  (2)  Blood, 
whether  bright  or  coffee-ground  color.  (3)  Mucus.  (4)  Odor.  (5) 
Apparent  amount  of  gastric  juice,  keeping  in  mind  that  after  diges- 
tion is  complete  the  secretion  of  gastric  juice  should  cease.  Continu- 
ous secretion  is  abnormal  and  is  known  as  parasecretion  (Ewald). 

Microscopic  Examination.— Here  are  to  be  looked  for  food 
fragments,  starch  granules,  plant  cells,  muscle-fibers,  connective 
tissues,  epithelial  cells  from  mouth  and  esophagus,  cylindric  cells 
from  the  stomach,  leukocytes,  red  blood-cells,  pus-cells,  parasites, 
and  low  organisms,  as  yeast  cells,  mold  fungi,  sarcinae,  bacteria. 

Gastric  Acids. — In  the  first  stage  of  digestion  there  may  be  a 
predominance  of  lactic  acid  developed  in  the  fermentation  of  the 
carbohydrates  by  the  Bacterium  lactis;  in  the  second  stage  both 
lactic  and  hydrochloric  acids  occur;  in  the  third  stage  hydrochloric 
acid  has  checked  the  formation  of  lactic  acid,  and  the  acid  reaction 
now  is  due  almost  exclusively  to  hydrochloric  acid.  Decomposition 
of  the  stomach  contents  may  be  prevented  for  some  time  by  the 
antifermentative  action  of  the  hydrochloric  acid.  If  the  acid  be 
neutralized,  the  chyme  ferments  produce  lactic,  acetic,  and  butyric 


GASTRIC    CONTENTS  547 

acids.  To  various  disease  germs  hydrochloric  acid  is  an  antiseptic 
when  present  in  normal  proportions,  killing  the  cholera  germ  and 
the  micrococci  of  pus.  It  is  one  of  our  chemical  defenses  against 
disease,  but  it  does  not,  however,  destroy  the  bacillus  of  tuberculosis 
nor  that  of  anthrax.  It  has  another  action  in  promoting  the  sol- 
ution of  the  calcium  and  magnesium  salts  which  are  required  for 
the  growth  of  bone. 

The  quantity  of  hydrochloric  acid  bears  an  important  relation 
to  certain  pathologic  states,  and  must  be  determined  so  as  to  aid  in 
diagnosis.  When  there  is  an  excess,  the  symptom  is  called  hyper- 
chlorhydria;  when  it  is  deficient,  hypochlorhydria;  when  absent, 
achlorhydria,  and  when  normal,  euchlorhydria. 

It  is  not  only  necessary  to  ascertain  the  degree  of  acidity,  but 
also  the  nature  of  the  acid  or  acids  occurring.  This  may  be  done 
by  coloring  substances  which  give  characteristic  reactions  with 
hydrochloric  acid  in  very  minute  quantities,  but  not  with  lactic 
acid  or  any  organic  acid  in  any  degree  of  concentration  found  in 
the  stomach.  It  is  conceded  that  these  reactions  are  not  suffi- 
ciently distinctive  for  exact  studies,  but  for  comparative  studies 
and  clinical  purposes  they  are  accurate  enough,  and  serve  the 
purposes  better  than  more  exact  methods,  too  difficult  for  the 
clinician.  To  simplify  the  study  and  provide  a  definite  point  in 
digestion  for  comparison  of  data,  it  is  customary  to  limit  the  in- 
quiry to  the  contents  of  the  stomach  one  hour  after  a  very  simple 
meal.  At  this  time  the  greater  part  has  not  passed  through  the 
pylorus,  the  secretion  of  hydrochloric  acid  has  about  reached  its 
height,  and  only  a  trace  of  lactic  acid  has  been  left  unabsorbed. 
All  the  components  of  an  ordinary  mixed  meal  in  an  easily  di- 
gestible form  are  represented  in  the  test-break jast  of  Ewald. 

The  test=meal  is  given  in  the  morning  as  a  breakfast.  It 
may  be  given  at  another  time,  provided  the  stomach  is  empty  or 
has  been  washed  out  as  a  preliminary  measure.  It  consists  of 
an  ordinary  roll  of  dry  bread,  weighing  about  35  gm.  (9  dr.),  and 
300  c.c.  or  about  10  fl.  oz.  of  hot  water  or  weak  tea,  taken  with- 
out cream  or  sugar.  In  one  hour  this  will  be  liquefied,  and  i  or 
2  fl.  oz.  (30-60  c.c.)  can  be  easily  expressed  through  a  tube. 

The  stomach-tube  offering  the  most  advantages  is  a  flexible  one 
of  soft  rubber,  smooth  on  the  surface  and  also  at  the  round  open- 
ing near  the  end  that  enters  the  stomach.  It  should  be  long 
enough  to  enter  the  stomach  and  leave  enough  tubing  outside  the 
mouth  to  reach  a  receptacle.  This  outer  end  may  have  a  funnel 
attachment  or  an  elastic  bulb  to  start  the  flow  of  the  gastric  contents 
until  the  tube  is  full  enough  for  siphon  action.  In  an  emergency  a 
Davidson  syringe  or  a  Politzer  bag  will  serve  to  start  the  flow. 

The  patient  sits  erect  in  a  chair  or  on  the  edge  of  a  bed,  with 


548  FOODS    AND    DIGESTION 

the  receptacle  near  by.  The  tube,  wet  in  hot  water,  is  passed  back 
to  the  throat  and  the  patient  makes  an  effort  at  swallowing.  Assist- 
ing deglutition,  it  readily  passes  into  the  stomach.  Evacuation 
may  occur  at  once,  without  effort,  simply  by  depressing  the  ex- 
ternal end  of  the  tube  so  as  to  make  a  siphon.  Pressure  over  the 
abdomen,  in  the  recumbent  posture,  while  the  patient  coughs  or 
bears  down,  is  of  material  help.  When  10  fl.  oz.  (300  c.c.)  of 
water  or  tea  have  been  given,  about  ij  fl.  oz.  (45  c.c.)  of  fluid 
should  be  obtained  by  the  tube.  Filtration  yields  a  clear  solution 
for  the  application  of  the  tests.  Should  there  be  much  gagging 
from  nervousness  or  pharyngeal  irritability,  a  spray  of  cocain  (4 
per  cent.)  will  prepare  the  way  for  the  tube. 

Dangers  to  be  Avoided. — Ordinarily,  the  use  of  the  stomach- 
tube  is  an  easy  and  safe  procedure,  but  it  is  contraindicated  in  acute 
fevers,  emphysema  with  bronchitis,  organic  heart  disease,  aortic 
aneurysm,  the  hemorrhagic  diathesis,  corrosive  poisoning  threat- 
ening perforation,  and  soft  carcinoma  of  the  stomach. 

The  specimen  from  the  test-meal,  when  examined  by  the  naked 
eye,  need  not  be  searched  for  all  of  the  numerous  objects  referred 
to  above.  If  the  contents  be  normal,  they  will  be  composed  of 
about  40  c.c.  of  a  whitish  fluid,  some  mucus,  and  a  sediment  of 
bread  debris.  After  nitration  the  fluid  should  contain  hydrochloric 
acid,  pepsin,  rennin,  peptone,  and  mineral  salts. 

The  chemical  examination  should  begin  by  the  use  of  litmus 
paper  to  determine  the  reaction.  Normally,  blue  litmus  will  be 
reddened;  if  it  be  unaffected,  then  there  is  a  condition  known  as 
Anacidity  (Plate  5,  Fig.  i). 

The  next  step  should  be  to  determine  if  the  acidity  be  due  to 
free  acid,  to  acid  salts,  or  acid  proteins.  Litmus  paper  does  not 
discriminate  these.  A  very  convenient  test  is  made  with  the  anilin 
colors,  Congo  red  or  tropeolin  oo  (dimethyl  orange),  both  of  which 
react  to  minute  quantities  of  free  hydrochloric  acid,  but  are  un- 
affected by  acid  salts  or  by  the  organic  acids  in  the  amounts  present 
after  the  test-meal.  A  positive  reaction  with  either  serves  for 
ordinary  purposes. 

Congo-red  Test. — Upon  Congo-red  paper  place  a  drop  of  the 
gastric  contents.  A  deep  blue  spot  appears  if  free  hydrochloric 
acid  be  present — as  much  as  0.005  Per  cent-  (tne  normal  amount 
is  0.25  per  cent.).  A  violet  spot  or  a  blue  ring  only  around  the 
wet  place  may  be  produced  by  any  free  acid,  either  a  trace  of 
hydrochloric  acid  or  some  organic  acid — lactic,  butyric,  or  acetic 
(Plate  5,  Fig.  2). 

Tropeolin  (Dimethyl-orange]  Test. — The  test  is  made  with  sat- 
urated alcoholic  solution  of  pure  tropeolin  (oo).  With  this  solu- 
tion wet  some  white  filtering-paper  and  then  let  it  dry.  Touch 


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PLATE  5. 

THE  MOST  IMPORTANT  COLOR-REACTIONS  OF  THE 
GASTRIC  JUICE. 

FIG.  1,  a  and  b.  When  the  gastric  juice  reddens  blue  litmus- 
paper  (b} — that  is,  exhibits  an  acid  reaction — it  may  contain: 
free  hydrochloric  acid,  lactic  acid,  and  other  organic  acids,  acid 
salts. 

FIG.  2,  a  and  6.  If  red  Congo-paper  is  stained  bluish-black  (b) 
by  the  gastric  juice,  only  free  hydrochloric  acid  or  lactic  acid  is 
present.  ,.j  .  >:r 

FIG.  3,  a  and  b.  If  upon  evaporation  of  the  gastric  juice  in  a 
porcelain  dish,  to  which  a  few  drops  of  phlorogludn-vanillin  solu- 
tion have  been  added,  a  distinct  red  ring  appears,  free  hydro- 
chloric acid  is  present ;  if  the  residue  remains  yellow,  no  free 
hydrochloric  acid  is  present  (anacidity). 

FIG.  4,  a  and  b.  If  the  gastric  juice  contains  hydrochloric 
acid,  the  violet  color  of  a  dilute  'methyl-violet  solution  is  converted 
into  blue  (6).  (This  test  is  not  absolutely  reliable.) 

FIG.  5,  a  and  6.  If  the  gastric  juice  contains  lactic  acid,  it 
will  change  the  violet  color  of  Uffelmann's  reagent  (~Lf0  solution 
of  carbolic  acid,  with  2  drops  of  iron  chlorid)  into  a  distinct 
yellow  (b}.  This  test  is  more  reliable  if  performed  with  an 
ethereal  extract  of  the  gastric  juice  (lactic  acid  being  soluble  in 
ether). 

(JAKOB.) 


PLATE   5. 


GASTRIC    CONTENTS  549 

the  prepared  paper  with  a  drop  of  the  gastric  contents.  When 
hydrochloric  acid  is  present  to  0.02  per  cent.,  a  dark  reddish 
brown  spot  appears,  which  changes  to  lilac  or  bluish  if  gently 
heated  on  a  watch-glass.  The  organic  acids  as  found  in  the  gas- 
tric contents  do  not  have  any  effect.  In  larger  amounts  they  make 
a  faint  brown  stain  which  does  not  show  a  lilac  color  when  heated. 

The  LIQUID  METHOD  of  performing  this  test  is  to  put  2  or  3  drops 
of  gastric  fluid  in  a  porcelain  dish,  spread  them,  and  evaporate 
almost  to  dryness.  Touch  this  residue  with  a  drop  of  tropeolin 
solution  and  gently  warm.  A  bluish  spot  indicates  free  hydro- 
chloric acid — at  least  0.02  per  cent.  No  organic  acid  gives  the  blue 
color. 

The  most  delicate  tests  for  distinguishing  hydrochloric  acid 
are  Topjer's  dimethylamido-azobenzol,  Gunzburg's  phloroglucin- 
vanillin,  and  Boas1  resorcin  solutions.  They  do  not  respond  to  the 
organic  acids  as  found  in  the  stomach  after  a  test-meal. 

Tbpjer's  solution  is  made  by  dissolving  0.5  gm.  of  dimethyl- 
amido-azobenzol in  100  c.c.  of  alcohol.  A  drop  of  the  gastric  juice, 
even  when  unfiltered,  will  turn  a  drop  of  this  yellow  solution  to  a 
cherry-red  color.  Organic  acids  affect  it  only  when  present  to  0.5 
per  cent.,  which  is  more  than  is  ever  found  in  the  gastric  contents 
after  a  test-meal  (Plate  6,  C,  C'). 

Gunzburg's  Test  (Phloroglucin-vanillin). — Use  the  reagent  fresh, 
though  it  will  last  for  a  short  while  when  kept  in  dark  bottles.  Not 
sensitive  to  organic  acids,  but  to  HC1  0.005  per  cent. 

Phloroglucin 2  parts  (30  gr.); 

Vanillin i  part  (15  gr.); 

Absolute  alcohol 30  parts  by  weight  (i  fl.  oz.). 

Or— 

Alcohol,  80  per  cent 100  parts  by  measure  (3  fl.  oz.). 

M. — Make  a  clear,  pale  yellow  fluid. 

Boas'  resorcin  solution  is  a  reagent  of  equal  delicacy,  has  greater 
stability,  and  is  cheaper  than  Giinzburg's.  Take  of — 

Resorcin,  pure 5  gm.; 

White  sugar 3  gm.; 

Dilute  alcohol 100  c.c. 

Method  for  Gunzburg's  or  Boas1  Tests. — About  5  drops  of  the 
test  solution  and  three  of  the  gastric  contents,  either  filtered  or 
unfiltered,  are  mixed  on  a  porcelain  dish.  Heat  the  dish  cautiously 
over  a  small  flame.  If  free  hydrochloric  acid  be  present  to  0.005 
per  cent.,  a  bright  red  ring  will  form  at  the  margin  as  the  mixture 
dries.  The  heat  should  not  be  above  110°  C.  (262°  F.),  or  char- 
ring will  ensue  (Plate  5,  Fig.  3). 

Import  in  Diagnosis. — The  regular  and  complete  absence  of  free 
hydrochloric  acid  in  the  contents  taken  one  hour  after  the  test- 


550  FOODS    AND    DIGESTION 

breakfast  is  an  indication  of  well-defined  structural  changes  in  the 
glandular  apparatus,  and  should  lead  us  to  suspect  atrophy  or 
amyloid  degeneration,  or  the  dilation  which  accompanies  gastric 
carcinoma  and  chronic  catarrh. 

A  striking  reduction  of  gastric  acidity  occurs  in  cancer  patients 
even  when  the  cancer  is  not  gastric,  but  located  in  other  parts  of  the 
body,  free  acid  being  absent  in  two-thirds  of  all  cases  of  cancer  and 
much  reduced  in  the  remaining  one-third.  In  the  cancerous  con- 
dition the  alkalinity  of  the  blood  plasma  is  increased  and  therefore 
there  are  fewer  hydrogen  ions  than  normal  for  the  gastric  cells  to 
secrete  in  the  form  of  free  hydrochloric  acid. 

If  the  absence  be  not  regular  or  persistent,  there  is  a  possibility 
that  the  deficiency  is  due  to  nervous  influences,  such  as  cause 
atonic  dyspepsia.  The  term  hyperchlorhydria  is  associated  with 
the  not  uncommon  condition  in  which  the  acid  is  secreted  in  excess. 
For  the  gastric  juice  to  contain  more  than  0.3  per  cent,  is  in  itself 
pathologic,  retarding  the  action  of  ptyalin  on  starch.  It  causes 
various  symptoms,  such  as  loss  of  weight  and  strength,  attended  by 
epigastric  pain  relieved  by  food,  which  holds  the  acid  in  check  for 
a  while.  More  than  0.5  per  cent,  impairs  peptic  action. 

ESTIMATION  OF  TOTAL  ACIDITY,  ACID  PROTEINS,  FREE  HC1,  AND 
ORGANIC  ACIDS 

The  procedure  generally  adopted  is  acidimetry,  operating  with 
the  same  standard  alkali  solution  upon  the  acid  gastric  contents 
in  three  different  dishes,  each  with  a  different  indicator,  to  make 
three  different  reports: 

Total  Acidity. — It  has  been  stated  above  that  hydrochloric 
acid  is  an  antiferment.  If  detected  in  the  gastric  contents  one 
hour  after  a  test-breakfast,  it  may  be  assumed  that  there  is  very 
little  organic  acid  present.  After  ascertaining  the  presence  of 
hydrochloric  acid  and  absence  of  lactic  acid,  to  determine  the 
total  acidity  is  practically  to  estimate  the  amount  of  hydrochloric 
acid  present.  A  more  thorough  study  is  needed  when  the  organic 
acids  are  detected. 

The  reagent  required  is  decinormal  sodium  hydroxid,  each  cubic 
centimeter  containing  0.004  gm-  of  NaOH,  which  neutralizes 
0.00364  gm.  of  HC1.  This  solution  should  be  carefully  standard- 
ized after  the  method  given  on  p.  125.  In  the  first  dish  the  indi- 
cator is  phenolphthalein,  i  per  cent,  alcoholic  solution,  which  is 
kept  colorless  by  all  free  acids  and  acid  proteins,  but  turns  red  by 
alkalis  (Plate  6,  A,  A'). 

Method. — To  10  c.c.  or  5  c.c.  of  the  filtered  gastric  fluid  in  a 
dish  or  beaker  2  drops  of  a  solution  of  phenolphthalein  are  added. 
A  buret  is  charged  with  the  decinormal  soda  solution,  and  a  few 


PLATE  6. 


g§§  OOET 

lllS.il 


g.     a 


GASTRIC   CONTENTS  551 

drops  at  a  time  are  run  into  the  liquid  until  a  deep  red  color  per- 
sists of  the  same  intensity.  If  10  c.c.  of  the  gastric  contents  have 
been  used  and  the  amount  of  hydrochloric  acid  be  normal,  it  will 
require  from  4  to  5  c.c.  of  the  solution  to  change  the  color.  One 
cubic  centimeter  will  neutralize  0.00364  gm.  of  HC1;  if  3  c.c.  have 
been  required,  then  the  acidity  is  calculated  thus:  3X0.00364  = 
0.01092  of  HC1.  To  get  percentage:  0.01092X10  =  0.1092  per 
cent,  of  HC1.  If  5  c.c.  of  gastric  liquid  were  used,  then  O.IO92X 
20  =  0.2184  per  cent,  of  HC1. 

The  acidity  is  expressed  for  clinical  purposes  by  the  number 
of  cubic  centimeters  of  decinormal  sodium  hydroxid  which  are 
required  to  neutralize  100  c.c.  of  the  stomach  liquid.  To  get  this 
when  the  operation  has  been  performed  on  10  c.c.,  multiply  the 
reading  by  10.  Acidity  of  45  per  cent,  would  then  mean  that  100 
c.c.  of  the  gastric  liquid  required  45  c.c.  of  decinormal  sodium 
hydroxid  to  neutralize  it.  It  would  be  spoken  of  as  "  total  acidity, 
45  degrees,"  in  terms  of  NaOH.  The  acidity  of  normal  gastric 
•contents  varies  between  40  and  60  degrees. 

Free  Acids  not  Combined  with  Proteins.— When  phenol- 
phthalein  is  the  indicator,  the  reaction  is  caused  by  all  free  acids 
and  by  loosely  combined  acids.  If  we  wish  to  estimate  the  free 
acids,  but  not  the  acid  protein  or  loosely  combined  acid,  we  must 
use  another  indicator. 

Alizarin  (sodium  alizarin  monosulphonate)  in  a  i  per  cent, 
aqueous  solution  is  acted  upon  by  all  acids  except  the  acid  proteins. 
The  difference  between  the  two  numbers,  total  acidity  and  acids 
not  acid  protein,  will  be  the  degree  or  number  representing  the  acid 
protein,  or  loosely  combined  acid. 

Procedure. — Add  2  drops  of  alizarin  sulphonate  as  an  indicator 
to  10  c.c.  of  stomach  contents  in  dish  No.  2,  and  from  a  buret  run 
into  it  slowly  the  decinormal  sodium  hydroxid  until  a  pure  violet 
color  appears  untinted  by  red.  The  combined  acid  does  not  figure 
in  the  color  changes  of  this  dye1  (Plate  6,  B,  B'). 

Acid  Protein. — If  2  c.c.  of  soda  solution  were  required  to  reach 
the  clear  violet  in  the  last  titration  and  3  c.c.  were  required  for 
total  acidity,  then  3  —  2  =  1  c.c.,  required  for  loosely  combined  acid; 
i  c.c.Xio=io  c.c.,  representing  degrees  of  combined  acid  in  100 
of  gastric  contents. 

1  Tbpfer  recommends  the  following  preliminary  steps  to  familiarize  the  eye  with 
the  color  required  in  the  reaction  with  alizarin  sulphonate: 

(a)  To  5  c.c.  of  distilled  water  add  a  few  drops  of  alizarin  solution.  A  clear 
yellow  color  results.  This  varies  somewhat,  at  times  a  clear  red  color  resulting. 

(ft)  To  5  c.c.  of  a  i  per  cent,  solution  of  disodium  phosphate  add  a  few  drops  of 
the  alizarin  solution.  A  reddish  color  with  a  tinge  of  violet  results. 

(c]  To  5  c.c.  of  a  i  per  cent,  solution  of  sodium  carbonate  add  a  few  drops  of 
alizarin  solution.  A  clear  violet  tint — the  reaction  to  be  recognized  in  the  test — 
results. 


552  FOODS    AND    DIGESTION 

Free  Hydrochloric  Acid.— As  alizarin  indicates  all  the  free 
acids,  to  ascertain  the  amount  of  free  HC1,  as  distinguished  from 
the  organic  acids,  another  indicator  must  be  used  which  is  affected 
by  the  hydrochloric  acid  only.  This  is  the  valuable  property  of 
Top/er's  reagent,  dimethylamido-azobenzol,  in  0.5  per  cent, 
alcoholic  solution. 

Method. — Having  filled  the  buret  with  decinormal  sodium  hy- 
droxid,  place  in  dish  No.  3  10  c.c.  of  gastric  contents  and  3  drops 
of  Topfer's  indicator,  which  is  yellow.  If  it  turn  red,  then  HC1 
is  present,  and  we  must  run  in  the  sodium  hydroxid  slowly  until 
the  yellow  color  is  restored.  If  this  be  done  in  the  proportion  of 
i  c.c.  for  the  10  c.c.  of  gastric  contents  used,  then  for  100  it  would 
be  i  X  10=  10  c.c.  of  decinormal  sodium  hydroxid  to  neutralize  the 
free  HC1  in  100  c.c.  of  gastric  contents,  or  10  degrees.  To  calcu- 
late percentage  in  weight  of  HC1:  10X0.00365  =  0.0365  gm.  in 
100  c.c.  of  gastric  contents  (Plate  6,  C,  C')« 

Organic  acids  and  acid  salts  are  estimated  by  subtracting  the 
degrees  of  free  HCl  from  all  acids  except  acid  proteins.  In  the  case 
above  given  the  calculation  would  be  20  degrees  less  10  degrees  =  10 
degrees  for  organic  acids  and  acid  salts. 

Detection  of  Lactic,  Acetic,  and  Butyric  Acids.— Lactic 
Acid  (Kelling's  Test). — To  5  c.c.  of  gastric  contents  add  50  to  100 
c.c.  of  water,  so  that  the  fluid  shall  not  be  yellow.  Treat  with  2 
drops  of  a  5  per  cent,  aqueous  solution  of  ferric  chlorid  and  hold 
to  the  light.  A  distinct  greenish  yellow  color  is  evidence  of  lactic 
acid  having  formed  ferric  lactate.  The  presence  of  a  small  amount 
of  hydrochloric  acid  has  no  influence  on  this  reaction,  which  is  due 
to  the  organic  salt  being  undissociated. 

It  is  not  interfered  with  by  the  organic  substances  of  the  gastric 
contents,  which  may  make  Uffelmann's  test  useless. 

Carbolojerric  or  Uffelmann's  Test. — Prepare  Uffelmann's  re- 
agent freshly  by  mixing  i  drop  of  a  dilute  solution  of  ferric  chlorid 
(U.  S.  P.)  with  2^  fl.  dr.  (10  c.c.)  of  a  4  per  cent,  solution  of  car- 
bolic acid  and  5  fl.  dr.  (20  c.c.)  of  water.  When  first  made,  the 
reagent  has^an  amethystine-blue  color  (Plate  5,  Figs.  5a  and  5b'). 

METHOD. — Equal  parts  of  Uffelmann's  reagent  and  filtered 
gastric  contents  are  mixed,  and  if  more  than  o.oi  per  cent,  of 
lactic  acid  be  present,  the  color  changes  to  canary  yellow  or 
greenish  yellow.  The  other  acids  may  discharge  the  blue  color, 
but  not  develop  the  yellow  if  the  very  unusual  amount  of  0.3  per 
cent,  be  present. 

Fallacies  may  occur  from  the  previous  color  of  the  gastric  fluid 
or  the  presence  of  glucose,  phosphates,  etc.,  giving  color  reaction 
that  masks  the  lactic  acid.  A  relatively  pure  and  concentrated 
sample  can  be  obtained  by  making  an  ethereal  extract.  Fill  a  test- 


GASTRIC    CONTENTS  553 

tube  three-fourths  full  with  the  gastric  fluid,  add  ether,  and  shake 
vigorously  some  minutes.  Stand  aside  till  the  ether  separates  at 
the  top  with  the  lactic  acid  in  it.  Then  pour  off  the  ether  into  a 
porcelain  dish.  Repeat  with  fresh  ether  three  times.  All  the  ether 
is  then  evaporated,  but  not  over  an  open  flame.  To  the  residue 
add  a  few  drops  of  water  and  then  Kelling's  ferric  chlorid  or  Uffel- 
mann's  carboloferric  reagent.  If  the  fluid  does  not  turn  yellow, 
there  is  no  lactic  acid. 

Acetic  and  Butyric  Acids. — The  above  ethereal  residue  reveals 
the  presence  of  any  acid  by  the  reaction,  and  the  volatile  acetic  and 
butyric  acids  by  their  odor. 

Butyric  Acid. — If  a  portion  of  the  ethereal  extract  be  diluted  and 
a  piece  of  calcium  chlorid  added,  the  light  butyric  acid  will  float 
like  oil  globules  on  the  saline  solution  below. 

Acetic  Acid. — A  portion  of  the  ethereal  extract  is  carefully 
neutralized  by  sodium  or  potassium  hydroxid,  i  drop  of  solution 
of  ferric  chlorid  is  added.  Acetic  acid  forms  red  ferric  acetate, 
which  on  boiling  precipitates  as  the  brownish  basic  salt. 

Import  in  Diagnosis. — It  has  been  found  that  85  per  cent,  of 
patients  showing  a  marked  amount  of  lactic  acid  have  malignant 
changes  in  the  wall  of  the  stomach.  This  lactic  acid  appears 
simultaneously  with  the  disappearance  of  the  hydrochloric  acid 
and  is  therefore  attributed  to  fermentative  changes  in  the  food 
which  would  have  been  prevented  if  the  hydrochloric  acid  had  been 
normal  in  amount  (p.  546). 

GASTRIC  DIGESTION  TESTS 

The  power  of  proteolysis  possessed  by  the  gastric  contents  is 
practically  dependent  on  the  presence  of  pepsin.  To  test  that 
power  is  to  prove  that  the  ferment  is  active,  provided  always  that 
provision  is  made  for  the  acidity  of  the  medium. 

Pepsin. — Fibrin  is  easily  digested  and  is  preferred  to  albumin, 
though  it  is  not  so  easily  obtained.  Let  fresh  blood  stand  till  it 
clots.  The  clot  washed  in  water  at  a  running  tap  loses  color  and 
is  called  fibrin.  It  can  be  kept  in  glycerin  and  washed  before  use. 
Into  a  test-tube  or  watch-glass  containing  2  dr.  or  more  of  filtered 
gastric  contents  put  2  drops  of  hydrochloric  acid  and  a  piece  of 
fibrin.  Stand  aside  for  a  half  hour  or  more  at  a  temperature  of 
40°  C.  (104°  F.).  If  pepsin  be  present,  the  fibrin  will  be  smaller 
by  partial  solution.  For  practice  the  student  can  make  an  artificial 
gastric  juice  by  dissolving  ij  gr.  of  pepsin  in  i  fl.  oz.  of  water  and 
adding  5  drops  of  hydrochloric  acid. 

Estimation  of  Pepsin  Strength.— Cut  hard-boiled  white  of  egg 
into  pieces  -fo  in.  (i  mm.)  thick,  and  punch  out  disks  J-  in.  (10  mm.) 
in  diameter.  Four  test-tubes  are  labeled  by  clasping  to  the  necks 


554  FOODS    AND    DIGESTION 

with  rubber  bands  pieces  of  paper  numbered  from  i  to  4.  A 
memorandum  must  be  kept  to  the  effect  that  there  is  added:  to 
the  first  2\  fl.  dr.  (10  c.c.)  of  the  clear  filtrate  of  gastric  contents; 
to  the  second,  the  clear  filtrate  +  HC1,  enough  to  make  0.3  to  0.5  per 
cent,  solution,  filtrate,  2j  dr.  (10  c.c.),  HC1,  2  drops;  to  the  third, 
the  clear  filtrate  +  pepsin  in  scales,  filtrate,  z\  dr.  (10  c.c.),  pepsin, 
3  to  7  gr. ;  to  the  fourth,  the  clear  filtrate +  HC1  + pepsin  as  in  2  and  3 
above;  place  all  in  a  warmer  at  40°  C.  (104°  F.)  and  watch  the 
progress  of  digestion  for  two  hours. 

If  pepsin  and  acid  be  present  in  normal  amount,  the  disks  will 
all  dissolve  in  one  to  two  hours.  If  the  acid  be  deficient,  then  solu- 
tion will  not  occur  in  samples  i  and  3,  but  will  occur  in  2  and  4. 
If  pepsin  be  deficient,  digestion  will  not  occur  in  i  and  2  as  rapidly 
as  in  3  and  4. 

Clinical  Import. — Absence  of  pepsin  is  rare  even  in  serious  dis- 
ease of  the  stomach.  Failure  in  gastric  digestion  is  seldom  due 
to  the  lack  of  it.  If  the  flakes  of  albumin  digest  without  adding 
hydrochloric  acid,  it  does  not  prove  a  normal  state  of  things,  as 
digestion  is  possible  by  the  presence  of  lactic  acid  alone,  though 
the  condition  is  not  a  healthy  one. 

Rennet  Ferment,  or  Rennin.— Take  a  small  amount,  z\  dr., 
of  neutralized  filtrate  and  add  an  equal  amount  of  neutralized 
boiled  milk.  Place  hi  warm  chamber  at  37.7°  C.  (100°  F.)  for 
ten  to  fifteen  minutes — the  milk  will  curdle. 

Digestion  of  Albumin. — It  is  seldom  of  any  value  to  carry 
the  investigation  further,  but,  if  desired,  tests  can  be  applied  to 
determine  the  progress  of  the  digestion  of  albumin,  as  follows: 

(1)  Heat  the  filtrate  of  stomach  contents  to  boiling: 

(a)  Coagulating  indicates  either  albumin  or  syntonin. 

(b)  No  coagulation  implies  that  there  may  be  propeptone 
(this  is  precipitated  by  cold  and  redissolved  by  heat) 
or  peptone  (heat  has  absolutely  no  influence  upon  it). 

(c)  If  the  filtrate  be  acid,  neutralize  a  fresh  portion  and 
heat.     A    precipitate    now    indicates    syntonin.     Filter 
and  use  filtrate  as  in  No.  3,  below. 

(2)  Biuret  Reaction. — Heat  the  filtrate  with  caustic  potash, 
and  add  dilute  solution  of  cupric  sulphate,  drop  by  drop,  from  pipet. 
Note  the  reaction. 

(a)  If  an  intense  purple-red  color  appear,  it  indicates  pro- 
peptone  or  peptone. 

(b)  If  a  bluish-violet  color  appear,  there  may  be  albumin  or 
syntonin  (Plate  8,  Fig.  7). 

(3)  From  c  of  No.  i,  above,  take  the  filtrate  and  treat  with 
acetic  acid  and  potassium  ferrocyanid.     If  there  be  no  precipitate 


PANCREATIC   JUICE  555 

and  the  biuret  be  positive,  then  peptone  is  present.  Confirm  by 
tannin  the  salts  of  heavy  metals  (mercuric  chlorid,  potassic  iodid, 
etc.),  or  phosphotungstic  acid,  all  of  which  precipitate  it. 

Motor  Function  of  the  Stomach.— The  lavage  test  is  used 
to  determine  if  there  be  pyloric  stenosis  or  other  condition  of  the 
stomach,  such  as  atony  or  dilatation,  which  prevents  the  propulsion 
of  the  contents  on  to  the  duodenum.  Method:  Give  10  raisins  or 
stewed  prunes  at  10  P.M.  and  wash  out  the  stomach  with  water  at 
9  A.M.  next  day.  Seeds  and  vegetable  tissue  should  not  be  found  in 
seven  hours.  In  defective  motility  they  are  sometimes  seen  even 
after  two  or  three  days. 

Peptic  Activity.— Sahli's  desmoid  test  is  based  upon  the 
observation  that  raw  catgut  is  digested  in  the  gastric,  but  not  in  the 
pancreatic  juice.  Method:  After  the  mid-day  meal  give  a  soft  pill 
of  methylene-blue  0.05  gm.  (J  gr.)  and  Ex.  glycyrrhizae  q.  s.  to  make 
a  pill  J  inch  in  diameter.  The  pill  is  wrapped  close  with  a  thin  sheet 
of  rubber  2  c.c.  in  diameter  and  tied  tight  with  3  turns  of  raw 
catgut  No.  oo,  previously  softened  by  soaking  over  night.  The 
pill  should  sink  in  water  and  not  color  it.  Examine  the  urine 
passed  at  7  P.M.  and  again  at  9  A.M.  next  day.  In  health,  the  first 
bluish-green  tint  appears  seven  hours  after  taking  the  pill.  If 
decided  color  shows  inside  of  twenty  hours  the  peptic  activity  is 
probably  good. 

PANCREATIC  JUICE 

The  changes  in  the  alimentary  bolus,  due  to  insalivation  and 
gastric  digestion,  may  be  regarded  to  a  large  extent  as  preliminary 
to  the  digestive  processes  of  the  intestines.  Those  earlier  alter- 
ations may  be  entirely  canceled  in  some  animals  without  material 
differences  in  the  products  of  digestion.  The  pancreas  is  the  only 
digestive  gland  in  many  animals,  and  is  found  in  all  that  have  an 
alimentary  canal.  In  the  higher  vertebrates  its  destruction  means 
death.  When  the  acid  contents  of  the  stomach  pass  into  the  duode- 
num, a  substance  is  secreted  by  the  duodenal  glands  called  secretin, 
which  enters  the  blood  and,  passing  to  the  pancreas,  starts  secre- 
tion there.  Reflex  excitation  of  the  pancreas,  liver,  and  intestinal 
glands  results  in  a  flow  of  alkaline  secretions,  which  put  a  stop  to 
gastric  digestion  by  destroying  the  reaction  of  the  chyme  and  sub- 
stituting one  favorable  to  the  activity  of  the  new  enzyms  that  are 
destined  to  carry  the  alimentary  bolus  through  complex  chemical 
changes  to  the  end-products.  Beside  the  internal  secretion  of  the 
pancreas,  which  is  taken  up  by  the  blood  and  serves  to  regulate  the 
sugar  production  from  glycogen  in  the  liver  and  from  protein 
metabolism  in  the  muscles,  there  is  the  external  digestive  fluid  elabo- 
rated by  the  gland  cells  from  the  blood  and  lymph  and  poured  into 


5  $6  FOODS    AND    DIGESTION 

the  intestines.  The  highest  rate  of  flow  occurs  about  three  hours 
after  eating,  but  there  is  another  rise  two  hours  later. 

The  total  amount  is  about  22  c.c.  per  kilo  of  body-weight  of 
the  animal.  In  man  the  daily  estimates  vary  between  150  c.c.  and 
500  c.c.  (J-i  pint).  It  is  a  strongly  alkaline  fluid,  clear,  colorless, 
odorless,  viscid,  with  a  specific  gravity  of  1008.  The  secretion  in 
the  dog  contains  about  i  per  cent,  of  solids,  two-thirds  of  which  is 
composed  of  albumins,  peptones,  and  ferments,  and  the  other  one- 
third  of  mineral  salts  and  such  organic  matter  as  leucin,  fat,  and 
soaps.  The  salts  are  equal  in  alkalinity  to  3  parts  per  1000  of 
sodium  carbonate.  The  ferments  include  at  least  three  enzyms 
that  are  well  defined,  and  two  others  about  which  little  is  known. 
In  the  first  group  are:  (i)  Amylopsin  (pancreatic  diastase,, 
amylase),  starch-splitting.  (2)  Trypsin  (protease),  protein-split- 
ting. (3)  Steapsin  (lipase),  fat-splitting.  In  the  little-known 
group  is  erepsin. 

The  relative  amounts  are  the  results  of  a  response  to  the  reflex 
stimulus  of  food.  A  diet  rich  in  starches  causes  a  rise  in  the  pro- 
portion of  amylopsin;  one  rich  in  fats,  an  increase  in  steapsin. 

Amylopsin  is  an  amylase  acting  like  the  ptyalin,  though  with 
greater  energy.  All  starchy  food  that  passes  the  stomach  unchanged 
is  at  once  converted  by  this  enzym  into  dextrin  and  maltose. 

Trypsin  is  a  protease  formed  from  the  zymogen  secreted  by  the 
gland  cells  by  the  action  of  a  constituent  of  the  intestinal  juice 
called  enterokinase.  It  is  soluble  in  water,  but  not  in  alcohol. 
When  acidulated  and  boiled,  trypsin  loses  its  enzymic  power  and 
breaks  up  into  an  albuminous  coagulum  and  a  peptone.  Its 
best  temperature  for  work  is  40°  C.(io4°  F.).  Traces  of  free 
mineral  acid  inhibit  its  action.  In  alkaline  solution  it  dissolves  its 
proteins,  fibrin,  albumin,  globulin,  and  gelatin  much  better  than 
the  pepsin  of  the  gastric  juice,  and  breaks  them  up  more  com- 
pletely. When  the  alkali  albumin  changes  to  the  dissolved  albu- 
moses,  these  change,  first,  to  peptones,  and  later,  by  the  aid  of 
another  enzym,  erepsin,  to  the  amino-acids  (leucin,  tyrosin,  aspartic 
acid,  the  sulphur  compound,  cystin,  etc.),  and  the  hexon  bases 
(lysin,  arginin,  and  histidin).  At  one  of  the  intermediate  stages, 
after  the  formation  of  albumose,  tryptophan  is  produced.  This  is 
skatol-amino-acetic  acid.  It  is  regarded  as  the  mother-substance 
of  the  aromatic  products  indol  and  skatol.  Its  presence  is  shown 
by  the  Adamkiewicz  reaction  (p.  500)  and  by  the  violet  color  pro- 
duced when  the  protein  mixture  is  acidified  with  acetic  acid  and 
treated  with  two  and  a  half  times  its  volume  of  bromin-water. 

Steapsin  has  the  property  of  hydrolyzing  and  splitting  fats  into 
glycerin  and  fatty  acids,  which  change  to  soap  by  union  with  the 


PANCREATIC  JUICE  557 

sodium  carbonate  of  the  intestinal  juices.  It  is  probatjle  that  this 
reaction  extends  to  the  separation  of  only  a  part  of  the  acid,  which, 
when  saponified,  aids  in  the  emulsification  and  absorption  of  the 
remainder.  Another  view  is  that  the  fat  is  all  split  first  and  passes 
through  the  intestinal  walls  as  soap  and  glycerin,  to  be  built  up 
again  by  cell  action  to  molecular  fat  on  the  other  side. 

Pancreatinum,  U.  S.  P.,  is  a  mixture  of  the  enzyms  obtained  from 
the  fresh  pancreas  of  the  hog  or  ox,  and  consisting  of  amylopsin, 
trypsin,  and  steapsin.  It  is  a  cream-colored  powder  with  a  faint 
odor  and  a  meat-like  taste.  It  is  slowly  soluble  in  water.  It  is 
rendered  inert  by  more  than  a  trace  of  mineral  acid,  by  excess  of 
alkalis,  and  by  pepsin  in  solution. 

Fermenting  Power.— The  most  powerful  and  active  fermenta- 
tion of  the  pancreatic  juice  is  that  of  conversion  of  starch  into 
maltose.  It  will  act  even  on  unboiled  starch.  For  this  test  an 
extract  may  be  made  by  bruising  finely  minced  fresh  pancreas  with 
glycerin. 

Experiment  i. — For  the  proteolytic  fermentation,  i  per  cent, 
solution  of  sodium  carbonate  is  put  in  a  test-tube  and  a  small 
amount  of  the  pancreatic  glycerin  is  added.  Put  some  of  it  in 
two  test-tubes  labeled  A  and  B.  To  A  add  a  piece  of  fibrin,  and 
after  boiling  the  contents  of  B  put  in  it  a  piece  of  fibrin.  Stand 
both  in  a  water-bath  for  thirty  minutes.  The  fibrin  in  A  will  look 
eroded,  not  swelled  as  by  gastric  juice,  and  when  tested  by  the 
biuret  reaction  gives  the  pink  color  due  to  peptone.  Tube  C  shows 
no  change  in  the  fibrin,  indicating  that  boiling  has  been  fatal  to  the 
ferment. 

Experiment  2. — Into  a  test-tube  labeled  C  put  starch  paste 
and  a  few  drops  of  the  glycerin  extract  of  pancreas,  without  soda, 
and  stand  in  a  water-bath  for  ten  minutes.  Take  out  a  few  drops 
and  test  every  minute  with  iodin  on  a  white  dish.  When  the  blue 
reaction  ceases,  test  with  Fehling's  solution;  maltose  will  be  shown 
by  the  red  precipitate. 

Experiment  3. — As  glycerin  does  not  dissolve  steapsin,  the  pan- 
creatic glycerin  will  not  serve  to  show  the  fat-splitting  fermentation. 
For  this  it  is  best  to  use  a  small  piece  of  fresh  pancreas  or  an  extract 
made  by  digesting  fresh  pancreas,  minced,  in  4  parts  of  dilute 
alcohol  (i  of  alcohol  to  4  of  water)  for  five  days  and  then  filtering. 
Into  a  test-tube  labeled  D  put  milk  and  blue  litmus  with  a  piece 
of  fresh  pancreas  and  stand  in  a  water-bath  for  thirty  minutes. 
The  liberation  of  the  fatty  acids  is  shown  by  the  litmus  turning  red. 

Experiment  4. — If  the  pancreatic  glycerin  with  sodium  carbonate 
.solution  is  shaken  with  olive  oil,  an  emulsion  is  formed. 


558 


FOODS    AND    DIGESTION 


BILE 

The  liver  secretes  bile  and  pours  it  continuously  into  the  duode- 
num. The  flow  increases  when  food  arrives  in  the  duodenum, 
and  a  second  wave  rises  some  hours  later,  when  the  digestive  prod- 
ucts in  the  blood  stimulate  the  hepatic  cells.  It  is  yellow  to  green 
in  color,  alkaline  in  reaction,  and  of  a  specific  gravity  between  1010 
and  1040.  The  daily  amount  in  man  varies  from  500  to  1000  c.c. 
(1-2  pt.). 

In  100  parts  about  14  are  solids,  the  rest  being  water.  Of  the 
solids,  sodium  grycocholate  and  taurocholate  make  9  per  cent.; 
cholesterin,  lecithin,  and  fat,  1.18;  mucinoid  material  and  pigment,. 
3;  inorganic  salts,  0.82.  The  characteristic  salts  are  sodium  com- 
pounds with  complex  amino-acids — glycocholic  and  taurocholic. 
Glycocholic  acid  in  the  intestine,  or  by  the  action  of  dilute  alkalis 
and  acids,  hydrolyzes  and  splits  into  glycin  (amino-acetic  acid) 
and  cholalic  acid;  thus: 


C26H43N06 

Glycocholic  acid. 


H20    = 


CH2  .  NH2  .  COOH 

Amino-acetic  acid. 


C24H4005 

Cholalic  acid. 


Taurocholic  acid  contains  sulphur,  and  splits  after  hydrolysis 
into  taurin  (amino-ethyl-sulphonic  acid)  and  cholalic  acid;  thus: 


C26H45N07S    +    H20    =    C2H4  .  NH2  .  HSO3 

Taurocholic  acid.  Taurin. 


C24H40O5 

Cholalic  acid. 


Pettenkofer's  reaction  (p.  560)  is  obtained  by  mixing  the  bile 
salts  with  cane-sugar  and  sulphuric  acid  or  with  furfurol  direct. 
A  bright  red  color  appears  and  later  changes  to  violet. 

Cholesterin  is  present  in  the 
nerve  tissues,  the  blood-corpus- 
cles, semen,  pus,  etc.  It  is  a  con- 
stituent of  the  fat  obtained  from 
sheep's  wool  (lanolin).  Only 
a  small  quantity  is  contained  in 
normal  bile,  but  at  times  it  be- 
comes excessive  and  forms  con- 
cretions known  as  gall-stones. 
Though,  like  fats,  it  is  soluble- 
in  ether,  it  is  not  a  true  saponifi- 
able  fat,  but  an  alcoh'ol  with  the 
formula  C27H45OH.  Part  of  the 

FIG.  84.  —  a,  Cholesterin  crystals;  b,  cystin  crys-  _  „!  rof      r,Ja.hr    1*™™     TT      Q      P 

tals  (Salinger  and  Kalteyer).  WOOl-iat,    ddepS    ldn(R,    U.    b.    -T., 

is  cholesterin  in  combination  as 

esters    of    fatty    acids.     A  deps   lance    hydrosus    with    drugs    makes 
stable    emulsions    which    readily    penetrate    the    skin    and    carry 


INTESTINAL  JUICE  559 

medicaments  with  them.  Cholesterin  is  odorless,  insoluble  in 
water,  but  soluble  in  alcohol,  which  on  evaporation  leaves  it  in 
rhombic  plates  (Fig.  84). 

Qall=stones  are  sometimes  small  and  easily  passed,  though  the 
concretion,  which  in  passing  the  bile-duct  gives  hepatic  colic,  is 
ordinarily  the  size  of  a  small  die.  The  concretion  may  be  as  large 
as  the  gall-bladder.  It  may  be  solitary,  though  they  are  usually 
multiple.  For  each  flat  facet  on  the  surface,  one  other  stone 
must  have  compressed  it.  They  are  usually  polyhedral.  The 
color  varies  in  different  stones — white,  yellow,  green,  red,  or  black. 
When  first  voided  they  are  soft  and  friable,  or  waxy  and  soapy.  On 
keeping  they  become  hard.  The  specific  gravity  varies  from  0.8  to- 
1.15.  A  transverse  section  shows  usually  a  nucleus  of  cholesterin 
crystals  or  pigment  surrounded  by  a  zone  of  radiating  structure 
and  a  cortex  that  is  in  concentric  layers.  The  average  composition 
is  70  or  80  per  cent,  cholesterin  with  pigment,  but  it  may  be  mainly 
pigment  or  calcium  carbonate. 

The  bile  pigments  are  chiefly  two,  bilirubin  and  biliverdin.. 
They  are  formed  by  the  breaking  up  of  hemoglobin.  The  bile 
of  carnivora  is  yellow  because  bilirubin  predominates  in  it;  that 
of  herbivora  is  green  from  the  abundance  of  biliverdin.  The  iron- 
free  crystals  of  hematoidin  found  in  old  blood-clots  are  identical 
with  bilirubin,  and  go  to  prove  its  derivation  from  hemoglobin 
(Plate  4,  Fig.  2).  Bilirubin,  C16H14N2O3,  when  oxidized  by  the 
air  or  by  nitric  acid,  takes  up  i  atom  of  oxygen  and  becomes 
biliverdin,  C16H18N2O4.  In  Gmelin's  test  with  nitric  acid  (p.  560) 
the  color  changes  with  the  successive  degrees  of  oxidation  into- 
green,  blue,  and  red  pigments,  and  finally  to  yellow  choletelin,. 
C16H18N2O6.  By  reduction  processes  in  the  intestine  the  bile  pig- 
ments yield  stercobilin,  the  pigment  of  the  feces.  A  portion  of 
it  is  absorbed  and  finally  escapes  from  the  body  as  the  pigment 
urobilin  of  the  urine. 

The  role  of  bile  is  to  a  great  extent  that  of  an  excretion.  It 
does  not  contain  enzyms,  but  acts  as  an  auxiliary  to  the  pancreatic 
juice,  neutralizing  the  acid  gastric  juice  from  the  stomach,  assisting; 
in  the  saponification  and  absorption  of  fat  and  the  digestion  of 
starch.  Its  alleged  antiseptic  powers  are  considered  doubtful. 


INTESTINAL  JUICE 

In  addition  to  the  pancreatic  juice  and  bile  the  mixed  secre- 
tions of  the  duodenal  (Brunner's)  and  intestinal  (Lieberkuhn's) 
glands  have  a  digestive  action  on  the  food  after  it  leaves  the 
stomach.  This  succus  entericus  appears  to  have  no  independent 
effect  on  native  proteins  or  fats,  though  it  probably  has  three 


560  FOODS    AND    DIGESTION 

ferments  with  the  power  of  "inverting,"  severally,  maltose,  cane- 
sugar,  and  lactose.  Together  these  are  called  invertin  or  invertase, 
because  their  effect  on  the  dextrorotatory  disaccharids  is  to  hydro- 
lyze  and  split  them  into  dextrose  and  levulose,  the  latter  inverting 
the  direction  of  rotation  of  the  polarized  ray  (p.  436). 

The  trypsinogen  of  the  pancreatic  juice  has  no  proteolytic  action 
until  the  trypsin  is  set  free  by  a  ferment  of  the  intestinal  juice  called 
enterokinase. 

Recent  researches  appear  to  demonstrate  that  the  proteoses  and 
peptones  are  not  absorbed  as  such,  but  are  probably  first  broken  up 
to  amino-acids  and  hexon  bases  in  the  intestinal  wall  by  another 
ferment  called  erepsin,  and  that  the  various  tissue  substances  are 
formed  synthetically  from  these  comparatively  simple  crystalline 
end-products.  The  protein  molecule  may  be  compared  to  a  barrel 
made  of  staves  of  amino-acids.  Digestion  removes  what  may  be 
called  the  hoops,  and  the  staves  fall  apart.  The  synthetic  powers 
of  the  tissue  cells  put  them  together  again  in  such  arrangements 
as  are  fitted  to  the  structure  of  the  tissue. 

Experiment  i  (on  Ox-bile). — Having  observed  its  green  color, 
bitter  taste,  odor,  and  alkaline  reaction,  take  the  specific  gravity. 
It  will  be  between  1020  and  1030. 

Experiment  2. — Put  a  small  quantity  in  a  test-tube  and  add 
acetic  acid.  A  string-white  precipitate  forms  of  mucin  and  nucleo- 
albumin. 

Experiment  3  (Pettenkojer's  Test  jor  Bile  Salts).—  Shake  to- 
gether, in  a  test-tube,  bile  and  a  grain  of  cane-sugar.  Pour  strong 
sulphuric  acid  down  the  side;  it  makes  a  purple  color  in  the  fluid 
and  froth.  This  denotes  the  presence  of  the  biliary  salts. 

Experiment  4  (Gmelin's  Test  jor  Bile-pigment). — On  a  white 
plate  or  capsule  smear  a  layer  of  bile  and  let  fall  upon  it  a  drop 
of  yellow  nitric  acid.  A  play  of  colors  at  the  line  of  junction  shows 
the  stages  of  oxidation  of  bilirubin. 

Experiment  5. — Cholesterin  in  a  concretion  supposed  to  be  biliary 
or  in  a  piece  of  lanolin  may  be  shown  by  dissolving  a  portion  of  the 
concretion  in  warm  alcohol  and  evaporating  a  few  drops  on  the 
slide  of  a  microscope.  Rhombic  plates  form  (Fig.  84),  and  if 
heated  with  a  drop  of  strong  sulphuric  acid,  they  turn  red  at  the 
edges. 

Salkowski's  Test. — Having  dissolved  cholesterin  in  chloroform, 
gently  shake  with  an  equal  quantity  of  strong  sulphuric  acid.  A 
blood-red  color  appears  in  the  solution,  while  the  acid  takes  a 
green  fluorescence.  Poured  on  a  white  plate,  the  chloroform  gives 
a  play  of  colors,  blue,  green,  and  yellow. 


BLOOD 


BLOOD 

THE  composition  of  the  blood  varies  according  to  the  part  of  the 
system  from  which  it  is  taken,  and  according  to  the  conditions  of 
food  and  fasting,  exercise  and  rest,  health  and  disease.  It  is  always 
a  red  or  purple,  neutral  reacting  liquid,  with  a  characteristic  odor. 
While  circulating  in  the  body,  it  is  shown  by  the  microscope  to 
consist  of  a  fluid,  plasma,  carrying  in  suspension  minute  bodies, 
the  red  and  white  corpuscles  and  the  platelets.  These  corpuscles 
constitute  40  per  cent,  of  the  volume  of  the  blood  and  48  per  cent, 
of  its  weight,  and  the  red  ones  are  sufficient  in  amount  to  give  to 
the  blood  its  crimson  hue  (Fig.  85). 


FIG.  85. — Cells  of  blood:  a,  Colored  blood-corpuscles  seen  on  the  flat;  b,  on  edge;  c,  in  rouleaux;  d, 

blood-platelets  (Leroy). 

In  freshly  drawn  blood  the  red  corpuscles  are  characterized  by 
their  color,  their  biconcave  shape,  and  their  tendency  to  form 
columns  like  rolls  of  coin.  They  consist  of  a  homogeneous,  semi- 
solid  substance  that  breaks  up  under  reagents  into  a  colorless 
elastic  stroma  and  a  red  coloring-matter.  The  white  corpuscles 
are  found  in  the  spaces  between  the  rolls  of  red  corpuscles.  They 
are  grayish  and  globular.  They  consist  of  a  transparent  substance 


FIG.  86.— Various  forms  of  leukocytes:   a,  Small  lymphocyte;  b,  large  lymphocyte;  c,  polymorphonu- 
clear  neutrophile;  d,  eosinophile  (Leroy). 

embedding  granules — fatty,  proteid,  and  carbohydrate.  They 
have  nuclei  and  are  capable  of  ameboid  movements.  They  can 
protrude  and  retract  portions  of  their  bodies,  and  thus  envelop  and 
expel  foreign  bodies.  They  can  also  squeeze  through  the  walls  of 
the  capillaries.  By  staining  they  can  be  differentiated  into  four 
forms,  believed  to  be  stages  in  development  (Fig.  86),  small,  large, 
36 


562  CLINICAL    CHEMISTRY 

mononuclear,  polymorphonuclear,  and  eosinophile  or  "  over-ripe"1 
cells.  The  blood-platelets  are  distinct  normal  cells,  grayish  white 
and  without  nuclei.  They  appear  to  be  involved  with  the  cor- 
puscles in  aiding  coagulation. 

The  red  corpuscles  are  produced  chiefly  in  the  marrow  of  the 
long  bones;  the  white  are  derived  from  the  lymphocytes  of  the 
lymph-glands.  The  red  corpuscles  are  carriers  of  oxygen;  the 
white  are  the  phagocytes  or  scavengers,  destroying  and  removing 
particles  of  disintegrated  tissue  and  the  invading  bacteria  of  disease. 

The  blood  coloring-matter  is  treated  of  in  another  place  (p.  529). 

Blood=plasma  is  the  colorless  liquid  which  bears  food  to  the 
tissues  and  in  which  the  cellular  elements  float.  In  its  8.9  per  cent, 
of  solids  the  proteins  constitute  6.9  per  cent,  and  the  inorganic 
salts  0.84,  the  remainder  being  carbohydrates,  fats,  and  waste 
organic  material.  Sodium  carbonate  and  disodium  phosphate 
both  contribute  to  give  it  an  alkaline  reaction.  A  proportion  of 
phosphoric  acid  exists  in  combination  with  proteins.  The  protein 
substances  are  serum-albumin,  serum-globulin  (paraglobulin), 
and  fibrinogen  (metaglobulin).  Varying  amounts  of  oxygen  and 
carbon  dioxid  distinguish  arterial  and  venous  blood.  Oxygen  to 
the  extent  of  0.26  per  cent,  is  dissolved  in  the  plasma;  a  larger 
amount,  22  per  cent.,  circulates  loosely,  combined  with  the  hemo- 
globin of  the  red  corpuscles.  Carbon  dioxid  to  the  extent  of  40 
per  cent,  exists  in  the  plasma,  partly  as  alkaline  carbonates  and 
partly  as  a  loose  organic  compound.  In  the  act  of  breathing  air 
comes  to  the  walls  of  the  alveolar  capillaries.  At  the  body  tem- 
perature there  is  a  high  rate  of  diffusion  between  the  gases  of  the 
alveoli  and  those  in  the  blood.  Oxygen  constantly  passes  into  the 
blood  and  carbon  dioxid  passes  out. 

Coagulation. — While  in  the  circulation,  blood  is  a  fluid  of 
a  specific  gravity  of  about  1060.  Soon  after  it  is  drawn  from  the 
vessels  it  suddenly  becomes  a  solid  jelly  with  a  slight  evolution 
of  heat.  On  standing,  the  clot  contracts,  leaving  a  straw-colored 
liquid  called  serum.  The  clot  itself  is  composed  of  corpuscles 
enclosed  in  a  mesh  of  fibrin.  Washing  at  the  tap  removes  the  cor- 
puscles and  leaves  the  shreds  of  fibrin.  Coagulation  is  due  to  a 
change  in  the  dissolved  fibrinogen  (metaglobulin),  brought  about 
by  the  presence  of  calcium  salts  and  an  enzym — thrombase.  Cal- 
cium is  necessary  for  clotting.  The  ferment  appears  to  cause  a 
combination  of  the  fibrinogen  with  the  calcium,  resulting  in  the 
coagulated  protein.  As  the  fibrin  comes  out  of  the  plasma,  there 
is  left  the  serum.  This  retains  two  proteins — albumin  and  glob- 
ulin— and  the  enzym — thrombase.  If  magnesium  sulphate  be 
added  to  saturation,  the  globulin  is  precipitated.  After  filtration 
the  filtrate  contains  albumin,  which  is  precipitated  by  saturation 


BLOOD  563 

with  ammonium  sulphate.  After  nitration  of  this  precipitate  the 
filtrate  does  not  respond  to  tests  for  proteins — i.  e.,  nitric  acid, 
heat,  and  the  biuret  reaction. 

Biologic  Test.— In  another  place  (p.  523)  definitions  have 
been  given  of  the  terms  hemolysin  and  precipitin.  When  an  albu- 
minous substance  from  one  animal  is  injected  into  another  of 
different  species,  "  antibodies"  form,  which  precipitate  it.  This 
precipitin  is  specific  for  that  albumin  and  distinguishes  it  from  all 
others,  even  when  by  ordinary  chemical  or  physical  reactions  no 
difference  can  be  detected.  After  cows'  milk  has  been  injected  into 
the  peritoneum  of  a  rabbit  the  serum  of  the  rabbit  precipitates 
the  casein  of  cows'  milk,  but  has  no  effect  on  the  milk  of  other 
animals.  When  a  rabbit  has  been  immunized  by  repeated  injec- 
tions of  small  quantities  of  human  blood,  peculiar  hemolysins  and 
precipitins  are  found  in  the  blood-serum  of  the  rabbit.  This 
serum  has  a  hemolysin  which  disintegrates  human  blood-corpuscles 
and  precipitates  dilute  human  serum  when  in  the  proportion  of 
i  :  100,  but  not  that  of  the  ape  until  the  concentration  is  i  :  30, 
nor  that  of  the  dog  until  it  reaches  i  :  10.  It  appears  that  though 
the  precipitin  is  specific,  the  blood  of  other  animals  may  show 
some  proportions  of  it,  according  to  the  closeness  of  their  rela- 
tionship. By  means  of  this  test  blood-stains  can  be  traced  to  their 
origin  in  man  or  in  some  species  near  him  in  the  animal  scale.  For 
this  purpose  the  stain  is  dissolved  in  0.9  per  cent,  salt  solution  and 
filtered. 

Experiment  i. — Defibrinated  blood  may  be  obtained  at  the 
slaughter-house  by  whipping  freshly  drawn  blood  with  a  bundle 
of  twigs.  The  fibrin  collects  on  the  twigs  and  the  remaining 
blood  keeps  fluid.  Test  the  reaction  with  neutral  litmus  paper. 
After  washing  away  the  blood  a  blue  stain  shows  alkalinity. 

Experiment  2. — Put  in  a  test-tube  5  c.c.  of  hydrogen  peroxid, 
add  a  few  drops  of  blood,  and  note  the  foam  caused  by  oxygen 
bubbles  escaping  from  the  peroxid.  The  blood  is  a  catalytic  agent, 
from  the  presence  of  catalase,  and  also  from  a  peroxidase  (p.  538). 

Experiment  3. — Guaiac  Test. — Put  a  small  lump  of  freshly 
broken  gum  guaiac  into  a  test-tube  containing  alcohol  and  boil 
until  deep  yellow.  Filter  and  add  filtrate  to  dilute  blood  to  make 
an  emulsion.  Pour  in  gently  hydrogen  peroxid;  a  blue  ring  forms. 
If  the  quantity  of  blood  is  small,  then  a  few  drops  of  the  emulsion 
is  added  to  a  fragment  of  sodium  perborate  on  a  white  plate.  The 
fragment  turns  blue  and  changes  later  to  green. 

Experiment  4. — Having  dried  a  drop  of  blood  on  the  slide  of 
a  microscope,  add  glacial  acetic  acid,  cover,  and  warm  until  bub- 
bles appear.  Oa  examination  Teichmann's  hemin  crystals  are 
seen  (Plate  4,  Fig.  3). 


564  CLINICAL    CHEMISTRY 

Experiment  5.— With  a  spectroscope  note  the  changes  in  the 
absorption  bands  induced  by  deoxidation  of  diluted  blood  with  am- 
monium sulphid  and  gentle  heat.  Observe  the  return  of. bands 
after  pouring  the  blood  back  and  forth  several  times  to  get  oxygen 
from  the  air.  Saturate  with  coal-gas  and  note  that  the  bands  now 
are  not  changed  by  ammonium  sulphid,  as  the  carbon  monoxid 
hemoglobin  is  a  fixed  compound  not  susceptible-  to  reduction  and 
oxidation  (Plate  4,  Fig.  i,  e.) 


EXAMINATION  OF  MILK 

Properties. — Normal  milk  is  a  sweet,  opaque,  bluish-white 
fluid,  with  a  peculiar  odor,  holding  in  solution  caseinogen,  albu- 
min, sugar,  and  mineral  salts.  Its  opacity  is  due  to  the  minute 
butter  globules  wrhich  are  suspended  in  it. 

Percentage  composition  of  normal  mil1:.  Cow.  Human. 

Water 87.41  87.29 

Solids,  as  tabulated  below I2-59  12.71 

Caseinogen 3.01  1.03 

Albumin 0.75  1.26 

Albuminoids 3-?6  2.29 

Butter  or  fat 3.66  3.78 

Milk-sugar 4.92  6.04 

Ash 0.70  0.31 

Microscopically,  the  milk  is  composed  of  minute,  brilliant  fat- 
globules  suspended  in  clear  plasma.  Immediately  after  birth  of 
the  child  human  milk  is  relatively  poor  in  casein,  but  rich  in  fatty 
matter,  which  exists  in  the  form  of  colostrum  masses  (Fig.  87). 

Morbid  Milk. — Human  milk  is  injured  by  excessive  emotion 
or  ill-health  of  the  mother  and  by  the  administration  to  her  of 
certain  drugs  that  pass  into  the  milk.  Cows'  milk  is  affected  in 
the  same  way  by  diet  and  by  disease,  such  as  tuberculosis,  foot- 
and-mouth  disease. 

Reaction. — Human  milk  turns  red  litmus  paper  blue,  show- 
ing alkalinity.  Cows'  milk  is  usually  alkaline  or  neutral  when 
fresh,  though  sometimes  acid  when  delivered  in  cities,  and  occa- 
sionally a  sample  will  be  found  that  is  amphoteric — that  is,  red- 
dens blue  litmus  paper,  and  turns  red  litmus  paper  blue.  This  is 
ascribed  to  the  presence  of  the  acid  phosphates  \vhich  dissociate 
hydrion  with  the  secondary  phosphates,  which  are  alkaline  from 
the  hydroxidion  they  dissociate  by  hydrolysis  (p.  188). 

Quantity. — The  average  secreted  daily  by  a  woman  is  i  L.,  or 
2  pt. 

Spontaneous  Change. — If  milk  stand  for  several  days  in  a  warm 
place,  it  coagulates  and  sours — that  is,  turns  acid  by  fermentation 


EXAMINATION    OF    MILK 


565 


of  the  sugar  (lactose)  into  lactic  acid,  C6H12O6=  2(C3H6O3).  The 
coagulum  consists  of  casein,  which  previously  existed  in  a  soluble 
form  of  union  with  calcium  phosphate  as  caseinogen.  This  curd  of 
casein  can  be  produced  by  any  acid,  as  in  the  following  experiment: 

Experiment  i. — Acid  Curd. — To  half  a  test-tubeful  of  diluted 
milk  (1:3)  add  a  drop  or  two  of  acetic  acid,  and  gently  warm;  an 
abundant  precipitate  falls.  This  precipitate  is  the  curdled  casein, 
carrying  with  it  most  of  the  fat. 

Experiment  2. — Put  into  a  test-tube  i  c.c.  of  milk  and  20  c.c.  of 
water.  Add  a  few  drops  of  solution  of  copper  sulphate  and  a  few 
drops  of  potassium  or  sodium  hydroxid  to  throw  down  the  proteins 
and  fat.  When  the  precipitate  falls,  decant  or  filter  off  the  clear 
liquid.  Boil  this  with  Fehling's  solution:  a  red  or  yellow  precipi- 
tate means  sugar  (lactose). 

Experiment  3. — Proteins. — Mix  equal  volumes  of  milk  and 
Millon's  reagent  in  a  test-tube  and  boil.  A  red  precipitate  proves 
the  presence  of  proteins  (casein  and  albumin). 

Milk=SUgar  and  Salts. — Having  filtered  the  whey  from  the 
acid  curd  and  tested  the  fil- 
trate with  Fehling's  solution,  it 
is  seen  that  the  milk-sugar  re- 
duces the  cupric  salt  and  pre- 
cipitates the  yellow  or  red  oxid. 
If  to  another  portion  we  add 
magnesia  mixture,  the  phos- 
phates are  precipitated.  On 
adding  to  another  portion  silver 
nitrate,  the  chlorids  are  precip- 
itated, insoluble  in  nitric  acid. 

Butter. — In  cows'  milk 
ether  will  not  dissolve  the  fat- 
globules  unless  they  are  lib- 
erated by  removing  their  en- 
velopes with  acetic  acid,  caustic 

potash,  or  soda.  With  human  milk  it  suffices  to  agitate  vigor- 
ously with  ether  alone.  In  churning,  the  envelopes  of  casein  are 
ruptured  mechanically,  and  the  fat-globules  cohere  in  large  masses 
of  butter.  This  process  does  not  separate  all  the  fat  as  butter. 
The  residue,  called  buttermilk,  still  contains  about  i  per  cent,  of 
fat.  As  it  is  formed  from  ripened  cream,  buttermilk  contains 
lactic  acid  formed  at  the  expense  of  the  lactose.  We  may  separate 
the  fat  by  the  following  experiment: 

Experiment. — To  a  test-tube  one-third  full  of  milk  add  half  its 
volume  of  potassium  hydroxid  and  half  of  ether;  shake  the  mixture 
and  stand  in  a  warm  place.  The  milk  clears  up,  and  the  butter 


FIG.  87.— a,  Milk;  b,  colostrum  (Wolf). 


566  CLINICAL    CHEMISTRY 

dissolved  in  the  ether  floats  at  the  top.  By  separating  the  ethereal 
layer  and  evaporating  it,  a  residue  of  butter  is  left. 

Pepsin  Curd. — The  first  act  in  the  digestion  of  milk  is  the  con- 
version of  caseinogen  to  casein,  and  its  coagulation  by  the  rennin 
of  the  gastric  juice.  This  can  be  shown  artificially  by  the  following 
experiment: 

Experiment. — Into  a  test-tube  about  one-third  full  of  milk  put 
a  few  drops  of  neutral  essence  of  pepsin  (Fairchild's).  Mix  gently, 
warm  to  the  temperature  of  the  body,  and  keep  at  40°  C.  (104°  F.). 
A  solid  curd,  containing  fat  entangled  by  the  casein,  forms  in  ten 
or  twelve  minutes,  so  that  the  tube  can  be  inverted  without  losing 
the  milk.  In  a  short  time  a  whey  separates  from  the  clot.  If  the 
experiment  be  performed  on  human  milk,  the  coagulum  is  not  a 
lump  of  curd,  but  floating  flocculi.  If  cows'  milk  be  boiled  or  if  it 
be  largely  diluted  with  lime-water,  the  same  loose  flocculi  form 
when  it  is  curdled  with  pepsin. 

Experiment. — Add  a  few  drops  of  dilute  hydrochloric  acid  to 
the  pepsin  curd,  so  as  to  make  with  the  pepsin  an  artificial  gastric 
juice,  and  set  aside  at  40°  C.  (104°  F.)  for  two  or  three  hours. 
The  curd  is  digested  and  gradually  dissolves  to  make  a  yellowish 
fluid  with  the  peculiar  odor  and  bitter  taste  of  peptonized  milk. 

If  the  milk  be  previously  boiled,  or  if  the  rennet  be  boiled,  the 
ferment  will  not  work. 

In  the  creameries  the  curds  are  a  by-product  from  which  alkali 
or  sodium  combinations  with  casein  are  produced  and  used  as 
condensed  foods  under  the  names  "  plasmon' '  and  "  nutrose.' ' 

Methods  of  Preservation. — To  prevent  the  lactic-acid  and 
other  fermentations,  several  procedures  are  resorted  to,  such  as 
refrigeration,  sterilization,  pasteurization,  and  the  addition  of  pre- 
servatives. 

Refrigeration. — If  a  sample  of  fresh  milk,  tested  with  litmus 
paper,  be  put  in  a  refrigerator  kept  at  or  below  10°  C.  (50°  F.) 
for  several  days,  the  reaction  will  be  but  little  changed,  the  milk 
having  kept  sweet  and  uncurdled.  Cold  will  not  preserve  milk 
indefinitely,  nor  will  it  kill  bacteria,  nor  alter  toxalbumins  after 
they  have  been  formed. 

Sterilization. — Fresh  milk  boiled  for  twenty  minutes  forms  a 
scum,  due  to  coagulation  of  the  lactalbumin  and  globulin.  By 
excluding  the  floating  dust  of  the  air  with  a  plug  of  cotton,  it  will 
keep  sweet  and  uncurdled  for  several  days,  owing  to  the  death  of 
the  bacteria  which  cause  lactic  fermentation.  So  far  as  infection 
is  concerned,  milk  sterilized  by  boiling  is  perfectly  safe;  at  the  same 
time  the  fats,  sugars,  casein,  and  albumin  are  altered  in  such  a  way 
as  to  make  boiled  milk  less  digestible  and  nourishing  than  raw 
milk.  A  lower  degree  of  heat  will  suffice  to  prevent  the  growth 


EXAMINATION    OF    MILK  567 

of  bacteria  for  a  short  while  and  not  injure  the  milk  as  an  assimilable 
food. 

The  temperature  sufficient  for  the  destruction  of  the  tubercle 
bacillus  is  68°  C.  (154°  F.);  for  the  typhoid  bacillus,  from  55°  to 
60°  C.  (i3i°-i40°F.);andfor  the  diphtheria  bacillus,  about  58°  C. 
(137°  F.).  Most  of  the  saprophytes  will  be  killed  at  a  temper- 
ature of  65°  to  75°  C.  (i49°-i67°  F.).  It  is  clear,  then,  that  if  we 
heat  milk  to  a  temperature  of  68°  to  75°  C.  (i54°-i67°  F.),  we  do 
not  materially  alter  its  taste  and  digestibility,  but  we  render  it 
practically  germless.  Bitter  and  Freeman  have  each  found  68°  to 
69°  C.  (i54°-i56°  F.)  the  suitable  temperature  for  the  purpose. 

Milk  heated  above  75°  C.  (167°  F.)  is  so  changed  that  chil- 
dren fed  on  it  exclusively  do  not  thrive.  There  are  several  enzyms 
in  small  amount,  galactase  which  digests  proteins,  amylase  for  carbo- 
hydrates, and  lipase  for  fats.  These  favor  the  digestion  of  milk,  but 
are  rendered  inactive  by  heat  above  75°  C.  (167°  F.).  Below  this 
point1  it  does  not  lose  the  taste  of  fresh  milk  nor  become  less  digest- 
ible. At  this  temperature  and  as  low  as  65°  C.  (150°  F.)  the 
matured  disease  germs  are  killed  and  the  spores  so  much  weak- 
ened in  vitality  that  all  liability  to  cause  intestinal  disorder  is  re- 
moved if  the  milk  be  used  within  twenty-four  hours  of  the  treatment. 

This  process  was  devised  by  Pasteur  and  bears  his  name;  its 
value  may  be  tested  by  the  following  experiment: 

Pasteurization. — Having  put  some  fresh  milk  in  a  clean  glass 
bottle,  stoppered  with  a  plug  of  cotton,  stand  it  in  a  vessel  of  water 
and  heat  the  water  to  70°  C.  (160°  F.)  for  a  few  minutes,  observing 
the  temperature  by  an  immersed  thermometer.  It  will  be  found 
to  keep  sweet  for  twenty-four  hours  at  least. 

Freeman's  Pasteurizer.—^  simple  apparatus  which  any  nurse 
can  use  with  accurate  results  is  the  pasteurizer  devised  by  Free- 
man. It  consists  of  a  metal  pail,  into  which  fits  a  receptacle  hold- 
ing the  bottles.  The  receptacle  is  so  made  that  each  bottle  fits 
into  a  separate  small  metal  cylinder.  The  pail  is  filled  with  water 
to  the  level  of  the  groove  running  around  it,  placed  on  the  stove, 
and  the  cover  put  on.  The  proper  amount  of  milk  for  each  feeding 
is  put  into  each  bottle,  the  bottles  plugged  with  raw  cotton,  and 
placed  in  the  receptacle.  Water  is  then  poured  around  them  into 
each  cylinder,  in  order  to  prevent  the  direct  action  of  the  hot  water 
in  the  pail  from  cracking  the  bottles.  As  soon  as  the  water  in  the 
pail  is  boiling,  the  pail  is  removed  from  the  fire  and  placed  out  of 
the  draught  upon  a  non-conducting  substance.  The  lid  is  now  re- 
moved, the  receptacle  put  in  ,  and  the  lid  reapplied.  It  is  left  thus 

1  A  constant  constituent  of  unheated  milk  is  an  oxidizing  enzym.  Its  absence 
may  be  regarded  as  proof  that  the  milk  has  been  heated  for  preservation.  The  test 
for  it  is  to  mix  with  10  c.c.  of  milk  i  c.c.  of  fresh  tincture  guaiac,  5  c.c.  of  turpen- 
tine, and  5  c.c.  of  hydrogen  dioxid.  Unheated  milk  gives  a  blue  color. 


568  CLINICAL    CHEMISTRY 

for  forty-five  minutes,  when  the  lid  is  removed  and  the  receptacle 
elevated  so  that  it  rests  upon  supports  which  hold  it  partially  out  of 
the  pail,  and  a  stream  of  cold  water  is  now  turned  into  the  pail 
for  fifteen  minutes.  The  bottles  are  then  kept  on  ice  till  needed. 
The  principle  of  the  apparatus  is  the  fact  that  the  given  quantity 
of  water  which  is  in  the  pail  will,  in  cooling,  elevate  the  temperature 
of  the  milk  to  the  desired  degree,  so  that  the  two  liquids  become  of 
the  same  temperature  at  68°  to  69°  C.  (i54°-i56°  F.).  Receptacles 
are  made  either  for  10  six-ounce  bottles  or  7  eight-ounce  bottles, 
and  either  receptacle  will  fit  into  the  pail. 

In  the  absence  of  a  thermometer  or  special  apparatus,  resort 
may  be  had  to  the  following  rough  method:  A  basin  containing 
several  inches  of  water  is  placed  on  a  slow  fire  and  the  cotton- 
stoppered  bottles  of  milk  placed  in  it.  After-boiling  the  water  for 
ten  minutes  the  milk,  which  has  not  boiled,  but  only  simmered,  is 
removed  and  kept  in  a  cool  place  until  used. 

If  the  milk  be  not  tolerably  fresh,  poisons  may  have  developed 
already.  Pasteurizing  will  not  destroy  the  toxalbumins  or  dissolved 
poisons  when  once  produced,  nor  render  stale  milk  harmless. 

Test  for  Pasteurized  or  Sterilized  Milk. — Heat  two  samples  of 
milk,  one,  A,  to  70°  C.  (160°  F.),  the  other,  B,  to  80°  C.  (176°  F.). 
When  cold,  test  both  separately  by  adding  to  each  a  small  amount 
of  solution  of  paraphenylendiamin  (C6H4(NH2)2),  and  then  a  few 
drops  of  hydrogen  dioxid.  The  unchanged  enzyms  in  A  cause 
instantly  a  deep-blue  color;  the  overheated  B  does  not  turn  blue 
for  some  time. 

Preserved  Milk. — To  prevent  bacterial  changes  in  milk  it  is 
quite  common  to  add  formaldehyd  or  boric  acid,  either  of  which 
is  tasteless  in  the  amounts  used. 

Formaldehyd  is  usually  added  as  formalin,  under  the  trade 
names  of  Preservalin  and  Freezene,  in  the  proportion  of  i  :  40,000, 
less  than  5  drops  in  a  gallon.  While  it  certainly  enables  milk  to 
be  kept  longer  in  warm  weather,  there  is  some  evidence  to  the 
effect  that  it  retards  slightly  the  digestion  of  protein  material, 
although  without  any  injurious  general  effect. 

Boric  acid  and  borax  are  employed  as  preservatives  by  adding 
to  i  qt.  of  milk  10  gr.  of  mixture  of  equal  parts  of  borax  and  boric 
acid,  or  35  gr.  of  boric  acid  to  the  gallon. 

It  is  not  likely  that  this  amount  would  cause  injury  to  the  average 
healthy  adult,  taking  an  ordinary  quantity  of  milk  with  other  food, 
but  it  would  very  likely  lessen  the  digestibility  if  not  prove  hurtful 
in  the  case  of  invalids  and  infants  (p.  209). 

Salicylic  acid  in  milk  may  be  detected  by  precipitating  fat  and 
proteins  with  mercuric  nitrate  and  acetic  acid,  filtering  and  agi- 
tating the  filtrate  with  ether,  which  dissolves  the  salicylic  acid. 


EXAMINATION    OF    MILK  569 

After  separation,  the  ethereal  solution  is  evaporated  and  yields  the 
acid  in  crystals.  These  are  dissolved  in  alcohol  and  tested  by 
ferric  chlorid,  which  gives  a  violet  color;  or  else  they  are  heated 
with  a  mixture  of  methyl  alcohol  and  sulphuric  acid,  when  the 
odor  of  wintergreen  reveals  the  presence  of  salicylic  acid. 

In  a  similar  manner  benzoic  acid  is  separated  and  identified  by 
its  reaction  with  ferric  chlorid  or  cupric  sulphate. 

Detection  oj  Formaldehyd  in  Milk. — Boil  the  suspected  sam- 
ple, i  part,  with  4  parts  of  commercial  or  yellow  hydrochloric  acid, 
which  contains  a  trace  of  a  solution  of  ferric  chlorid.  If  no  purple 
color  result  on  cooling,  dilute  with  an  equal  part  of  water,  add  a 
trace  of  ferric  chlorid,  and  boil  again.  The  purple  reaction  will 
sometimes  appear  better  in  the  weaker  solution. 

Hehner's  Test. — The  same  reaction  follows  the  test  made  by 
mixing  i  c.c.  each  of  milk  and  water,  and  pouring  the  mixture 
gently  on  4  c.c.  of  strong  commercial  sulphuric  acid  which  has  a 
trace  of  ferric  sulphate  or  chlorid.  If  the  sulphuric  acid  is  pure,  add 
a  drop  of  solution  of  ferric  chlorid.  The  line  of  contact  is  blue  or 
purple  when  formaldehyd  is  present,  but  with  pure  milk  ii  is  green. 
This  reaction  is  due  to  the  protein  of  the  milk  in  the  presence  of  a 
minute  quantity  of  formaldehyd.  It  will  detect  i  part  of  the  latter 
in  250,000,  and  shows  better  when  the  proportion  of  protein  is 
large.  Hence  if  the  purple  does  not  appear  at  first,  dilute  the 
milk  with  thinned  milk  of  known  purity,  and  try  again. 

Detection  oj  Boric  Acid  or  Borax  by  the  Turmeric  Test. — Place 
in  a  porcelain  dish  i  drop  of  the  milk  with  2  drops  of  strong  hydro- 
chloric acid  and  2  drops  of  a  saturated  turmeric  tincture.  Dry  the 
mixture  on  a  water-bath;  cool,  and  add  a  drop  of  ammonia  by  a 
glass  rod.  A  slaty-blue  color,  changing  to  green,  indicates  borax. 
A  drop  of  milk  containing  roVo"  gr-  °f  borax  will  give  this  reaction. 

Specific  Gravity. — The  hydrometer  employed  for  taking  the 
specific  gravity  should  be  very  accurate  and  carry  a  scale  for  the 
usual  variations  of  milk,  or  between  1000  and  1040.  The  lac- 
tometer of  the  New  York  Health  Board  is  a  hydrometer  with  a  scale 
on  which  100°  stands  for  a  specific  gravity  of  1029  (the  minimum 
density  of  pure  milk),  while  o°  stands  for  the  specific  gravity  of 
water,  and  120°  for  1034,  the  maximum  range  of  pure  milk.  On 
this  instrument  i°  is  read  as  i  per  cent,  of  milk  in  the  sample. 

For  cows'  milk  care  should  be  taken  to  shake  cream  and  milk 
together  before  testing. 

To  suit  the  small  amount  with  human  milk  smaller  instru- 
ments are  used. 

The  sample  taken  for  examination  should  be  from  the  middle  of 
the  nursing  or  when  the  breast  has  been  about  one-half  emptied,  as 
the  first  milk  is  always  poorer  and  the  last  richer  than  the  average. 


570 


CLINICAL    CHEMISTRY 


The  specific  gravity  should  be  taken  at  a  temperature  of  from 
18°  to  23°  C.  (65°-72°  F.).  By  giving  the  stem  of  the  lactometer 
a  twirl  as  it  is  introduced,  it  readily  settles  to  the  proper  level,  which 
may  otherwise  be  prevented  by  the  adhesion  of  the  milk  to  the 
glass,  especially  in  a  rich  specimen. 

The  specific  gravity  of  dairy  milk,  the  product  of  a  number  of 
cows,  should  never  fall  below  1029.  When  lower  than  this,  it  is 
usually  due  to  adulteration  with  water;  but  very  rarely  the  low 
density  is  due  to  excess  of  cream  in  very  rich  milk. 

The  quantity  of  cream  is  measured  by  an  instrument  known 
as  a  creamometer,  or  a  10  c.c.  glass-cylinder  graduate  may  be  used. 
Having  mixed  the  milk  thoroughly,  a  sample  is  poured  into  the 
vessel  up  to  the  highest  mark.  After  twenty-four  hours,  at  a  tem- 
perature between  15°  to  24°  C.  (6o°-75°  F.),  the  depth  of  cream 
layer  thrown  up  is  red,  each  degree  of  the  scale  being  i  per  cent. 
The  average  sample  of  cows'  milk  would  be  12  per  cent.  If  the 
cream  form  20  per  cent,  of  the  column,  the  sample  would  probably 
also  show  a  low  specific  gravity.  The  accuracy  of  this  test  is 
affected  by  the  length  of  time  since  milking,  by  the  amount  of 
previous  agitation  of  the  milk,  by  the  fact  that  dilution  causes  a 
more  rapid  separation  of  the  cream,  by  the  temperature,  and  other 
variable  conditions.  It  may  serve  a  useful  purpose  when  taken 
in  consideration  with  other  observations.  In  sorting  cows'  milk 
it  may  be  assumed  that: 

Less  than  10  per  cent,  oj  cream  in  a  milk  oj  specific  gravity  above 
1033  denotes  skimming. 

Less  than  20  per  cent,  oj  cream,  ij  joined  to  a  specific  gravity  less 
than  1020  indicates  watering. 

Clinical  testing  of  mothers'  milk  is  usually  confined  to  taking 
the  specific  gravity  with  a  small  special  lactometer  and  the  per- 
centage of  cream  in  a  small  10  c.c.  graduate. 


Specific  g 
70°] 

Normal  average 
Healthy  variations 


Unhealthy 


ivity, 


Human  Milk 

Cream — 24  hours. 


1.031  >j% 

1.028-1.029  9^-12$ 

1.032-1.033  Sf0-  &% 

Below  1. 028    High  (above  10% 
"        1.028    Normal  (5^-10$ 
"       1 .028    Low  (below  5  %  ) 
High 
Normal 


Proteins. 


Normal  (rich  milk). 

"         (fair  milk). 

"         or  slightly  below. 
Low. 

Very  low  (very  poor  milk). 
Very  high  (very  rich  milk). 
High. 
Normal  (or  nearly  so). 


Above  i  .033 
"  1-033 
"  1-033 

Human  milk  presenting  only  moderate  variations  from  the  average — e.  g.,  specific 
.gravity  1.028,  cream  4  per  cent.,  or  specific  gravity  1.033,  cream  10  per  cent.,  can 
usually  be  modified  by  appropriate  treatment.  If,  however,  the  specific  gravity  is 
from  1.018  to  1.024,  and  the  cream  only  2  per  cent,  to  3  percent.,  it  is  hopeless 
{Holt). 


EXAMINATION    OF    MILK 


571 


C. 


P. 


The  lactoscope  of  Feser  gives  good  results  for  ordinary  test- 
ing of  milk  to  determine  its  richness.  The  opacity  of  milk  is 
due  to  the  fat-globules,  and  is  proportionate  to  the  number  of 
them.  By  measuring  this  opacity  an  approximate  estimate  can  be 
made  of  the  percentage  of  fat.  For  making  this  estimate  roughly 
the  lactoscope  is  very  convenient.  In  the  axis  of 
a  cylindric  clear  glass  vessel  (Fig.  88)  and  at  its 
lower  part  (A)  is  a  smaller  cylinder  of  white 
glass,  marked  with  a  few  black  lines.  In  test- 
ing with  this  instrument,  4  c.c.  of  milk  are  intro- 
duced with  the  graduated  pipet;  the  black  lines 
are  entirely  concealed.  Pure  water  is  gradually 
added,  while  shaking,  until  the  milk  clears  up 
sufficiently  to  make  the  black  lines  distinctly 
visible.  There  is  a  range  of  i  per  cent,  be- 
tween the  point  where  the  lines  are  first  seen 
and  that  where  they  become  sharply  defined. 
By  the  graduation  on  the  vessel  the  surface  level 
of  diluted  milk  can  be  read  as  percentage  of  fat 
in  the  original  sample.  The  microscope  having 
determined  the  absence  of  chalk,  starch,  or  other 
suspended  adulterants,  a  sample  showing  3  per 
cent,  and  over  is  judged  pure.  Some  rich  Jersey 
milk  shows  6  per  cent.  Any  one  experienced  in 
its  use  will  be  accurate  to  within  J  of  i  per  cent. 
The  main  point  is  to  see  the  lines  well  defined 
and  not  hazy.  Having  obtained  the  specific 
gravity  by  the  lactometer,  and  the  percentage 
of  fat  by  the  lactoscope,  experiment  shows  that 
the  proportion  of  total  solids  can  be  calculated  by  the  formula  of 
Hehner  and  Richmond.1 

A  much  simpler  and  less  accurate  method  was  devised  by 
Heeren,  whose  pioscope  consists  of  two  disks.  One  of  them  is 
made  of  hard  black  rubber,  in  the  center  of  which  is  a  shallow, 
flat  cell,  of  22  mm.  diameter,  surrounded  by  a  ring  of  0.5  mm. 
in  height,  intended  for  the  reception  of  a  few  drops  of  the  well- 
mixed  milk.  The  other  disk  is  made  of  glass,  colorless  in  the 

iT_F-f  0.2186  G? 
0.859 

in  which  F  stands  for  percentage  of  fat,  T,  the  percentage  of  total  solids,  and  G,  the 
specific  gravity  expressed  in  the  last  two  units  and  any  decimal  ;  thus,  if  the  specific 
gravity  is  1028.5,  tnen  G  stands  for  28.5.  For  example,  if  a  specimen  of  milk  had 
a  specific  gravity  of  1030,  and  the  percentage  of  fat  was  4,  then — 

Total  solids  ^4+ (0.2186  X  3^1  =  I2.3  per  cent 
0.859 


FIG.  88. — Feser's    lacto- 
scope. 


572  CLINICAL    CHEMISTRY 

center  as  far  as  is  necessary  to  cover  the  central  cell  of  the  rubber 
disk,  while  on  the  margin  are  represented,  in  six  sections,  the 
various  tints  of  cream,  and  milk  from  very  rich  to  very  poor.  A 
comparison  of  the  color  of  the  milk  in  the  central  cell  with  the 
marginal  color  standards  is  rapidly  made  and  gives  results  suffi- 
ciently approximate  for  the  preliminary  testing. 

If  a  specimen  of  milk  fail  to  satisfy  the  requirements  of  these 
physical  tests,  or  if  it  become  desirable  to  investigate  more 
thoroughly  for  any  other  reason,  the  more  exact  methods  of 
examination  in  the  laboratory  must  be  resorted  to. 

The  creamometer  of  Chevelier  (Fig.  89),  or  one  of  its  modifi- 
cations, may  be  used  for  this  purpose.  In  this  instrument  the  milk 
is  left  at  rest  for  twenty-four  hours  to  give  time  for  the  cream  to  rise, 
whose  volume  is  then  measured  and  readily  shows  whether  the 
milk  has  been  tampered  with.  After  measuring  and  removing 
the  cream  the  specific  gravity  of  the  residue  may  be  taken,  and 
shows  by  its  lack  of  proper  density  the  addition  of  water.  In  its 
simplest  form  the  creamometer  is  a  glass  cylinder  of  about  35  mm. 
diameter  and  170  mm.  height.  Measuring  from  below,  marks  are 
made,  running  around  the  cylinder  at  50  c.c.,  100  c.c.,  and  150  c.c. 
The  interval  between  100  and  150  is  divided  into  30  equal  parts 
by  short  lines  of  division,  and  this  graduation  is  ex- 
tended to  10  of  these  units  above  150  and  below  100. 
Thus,  the  upper  half  is  divided  into  50  equal  parts. 

3  Milk  is  poured  into  the  instrument  up  to  the  upper- 
•  most  mark  of  graduation,  which  also  runs  around 
the  cylinder.  After  leaving  it  at  rest  for  twenty-four 
hours  the  supernatant  cream  is  measured,  each  unit 
of  the  graduation  corresponding  to  i  per  cent,  by 
volume.  Good  milk  should  not  yield  less  than  10 
per  cent,  of  cream.  After  removal  of  the  cream,  the 
specific  gravity  of  the  residue  is  increased  by  0.020 
FIG.  89.— Cream-  to  0.035  °^  tne  specific  gravity  of  the  fresh  specimen 
before  separation  of  the  cream.  A  less  voluminous 
layer  of  cream  than  ten  subdivisions  indicates  that  cream  has  been 
abstracted,  and  a  smaller  increase  of  the  specific  gravity  indicates 
the  additional  dilution  with  water.  The  means  of  applying  this 
test  are  simple  enough,  and  it  fairly  approximates  the  true  con- 
dition, but  requires  too  much  time  to  commend  itself  as  a  pre- 
liminary examination  to  be  left  to  the  subordinate  inspectors. 
To  reach  close  approximations  with  simple  apparatus  in  a  brief 
space  of  time,  the  optical  behavior  of  milk  is  examined  by  Feser's 
lactoscope. 

Modified  milk  is  cows'  milk  altered  by  dilutions  and  addi- 
tions in  such  a  way  as  to  bring  its  composition  nearer  to  that  of 


EXAMINATION    OF    MILK  573 

human  milk.  The  difference  in  the  proportion  of  the  two  proteins, 
caseinogen  and  albumin,  causes  cows'  milk  to  be  less  digestible 
in  the  human  stomach.  The  gastric  juice  makes  with  human  milk 
a  slight  flocculent  curd,  easily  dissolved  in  the  digestive  juices. 
This  is  due  to  the  small  amount  of  caseinogen,  which  is  the  only 
protein  coagulated  by  rennin.  As  cows'  milk  contains  four  times 
as  much  caseinogen  and  one-half  as  much  albumin,  it  forms  a 
tough,  abundant  curd  of  difficult  solubility. 

It  is  not  possible  artificially  to  produce  the  right  proportion  of 
the  two  proteins,  but  we  can  lower  the  proportion  of  caseinogen 
by  dilution  with  water.  Human  milk  averages  about  2  per 
cent,  more  in  sugar.  Other  differences,  such  as  the  alkaline  re- 
action, will  be  noted  on  referring  to  the  Tables  of  Composition  at 
the  beginning  of  this  chapter.  In  the  milk  laboratories  cows' 
milk  is  modified  to  resemble  human  milk  by  mixing  milk,  cream, 
lime-water,  water,  and  milk-sugar  in  the  right  proportion  for  the 
age  of  the  child.  The  exact  formula  varies  according  to  the 
period  of  lactation,  but  an  average  human  milk  is  closely  imitated 
by  a  mixture  of  milk,  2  fl.  oz.;  cream,  3  fl.  oz.;  water,  10  fl.  oz.; 
lime-water,  i  fl.  oz.;  and  milk-sugar,  4  dr.  It  is  customary  to 
pasteurize  the  mixture  and  deliver  it  fresh  in  bottles  stoppered 
with  plugs  of  cotton  to  exclude  bacteria. 

When  it  is  not  convenient  to  have  the  milk  mixture  made  at 
city  laboratories,  the  mother  will  find  useful  a  special  glass  graduate, 
called  "  Materna, "  which  holds  from  16  to  24  fl.  oz.  The  outer 
surface  is  divided  into  seven  vertical  panels,  and  each  of  these  is 
marked  to  show  how  much  milk-sugar,  milk,  cream,  lime-water, 
and  water  shall  be  mixed  to  get  a  product  of  a  certain  desired 
percentage  strength  for  an  infant  of  a  certain  age.  The  panels 
also  show  the  percentages  of  fat,  protein,  and  sugar  in  the  meas- 
ured amounts  of  the  ingredients.  The  first  is  marked  "fat  2  per 
cent.,  protein  0.6  per  cent.,  sugar  6  per  cent.,"  making  a  formula 
to  be  used  at  the  beginning  of  an  early  weaning.  The  second 
panel  is  marked  "fat  2.5  per  cent.,  protein  0.8  per  cent.,  sugar  6 
per  cent.,"  and  the  other  panels  show  progressively  increasing 
strengths. 

Milk  Standards.— By  the  United  States  Treasury  Depart- 
ment, cows'  milk  should  contain  by  weight  not  less  than  13  per 
cent,  of  solids  and  not  less  than  3.5  per  cent,  of  fat.  In  Philadel- 
phia it  must  have  not  less  than  12  per  cent,  of  solids  nor  less  than 
3.5  per  cent,  of  fat.  By  the  State  of  Pennsylvania  it  is  required 
to  contain  not  less  than  12.5  per  cent,  of  solids  and  not  less  than 
3  per  cent,  of  fat.  In  the  States  of  New  York  and  New  Jersey  it 
should  contain  not  less  than  12  per  cent,  of  solids,  nor  less  than 
3  per  cent,  of  fat.  The  English  Society  of  Public  Analysts  has 


574  CLINICAL    CHEMISTRY 

fixed  the  standard  for  Great  Britain  as  follows:  Total  solids,  11.5; 
fat,  3;  solids  not  fat,  8.5  per  cent. 

Total  Solids  by  Weighing. — The  determination  of  total  solids 
gravi metrically  consumes  considerable  time,  but  it  gives  accurate 
results.  Into  a  tared  dish  of  platinum  or  a  watch-glass  5  gm.  of 
milk  are  weighed  or  5  c.c.  measured.  The  dish  is  then  exposed 
to  the  heat  of  a  water-bath  for  three  hours.  As  evaporation  is 
nearly  done,  it  is  now  put  into  a  water  oven,  and  at  intervals 
weighed  until  it  ceases  to  lose  weight.  This  constant  weight,  less 
the  weight  of  the  capsule,  gives  the  total  solids.  The  difference 
between  the  5  gm.  and  the  constant  weight  of  the  dry  solids  rep- 
resents the  water.  By  carefully  incinerating  the  solids  to  a  grayish- 
white  color  the  ash  or  inorganic  salts  are  determined.  In  pure 
milk  the  amount  ranges  from  0.7  to  0.8  per  cent.  A  watered 
milk  will  show  a  reduced  amount  both  of  solids  and  of  ash. 

Determination  of  Fat  (Werner-Schmid  Process). — This  is  an 
easy  and  quite  accurate  method.  Into  a  long  test-tube  with  a 
capacity  of  50  c.c.,  and  graduated  to  show  cubic  centimeters  in  tens, 
measure  10  c.c.  of  milk  and  10  c.c.  of  strong  hydrochloric  acid. 
(A  large  common  test-tube  can  be  used,  and  the  measurement 
made  by  pipets  or  other  graduated  glasses.)  The  mixture  of  acid 
and  milk  is  boiled  one  and  one-half  minutes,  or  the  tube  may  be 
corked  and  heated  in  a  water-bath  for  five  or  ten  minutes,  until 
the  liquid  turns  a  deep  brown,  but  not  black.  Having  cooled  the 
tube  and  its  contents  in  running  water,  30  c.c.  of  well-washed 
ether  must  be  added,  the  tube  corked,  the  mixture  well  shaken, 
and  finally  stood  aside.  When  the  line  of  separation  between  the 
ether  and  acid  is  distinct,  a  wash-bottle  cork  stopper  with  its  tubes 
is  substituted  for  the  plain  stopper  (see  Fig.  90). 

The  lower  end  of  the  exit  tube  has  a  short  curve,  which  is  ad- 
justed so  that  its  opening  is  just  above  the  line  of  separation.  A 
weighed  flask  or  beaker  is  held  so  as  to  receive  the  ethereal  layer 
when  it  is  blown  out  by  the  lips  at  the  upper  tube.  In  succession 
two  additional  portions  of  washed  ether,  10  c.c.  each,  are  shaken 
with  the  acid  and  blown  out  into  the  weighed  flask.  The  ether  is 
then  distilled  off  or  evaporated,  and  the  fat  residue  dried  in  a  water 
oven  and  weighed.  It  is  the  amount  contained  in  10  c.c.  of  milk. 

Babcock's  Method  with  Centrifuge. — For  separation  of  fat  from 
either  human  or  cows'  milk  the  graduated  milk  bottle  (Fig.  91) 
may  be  used  with  any  medical  centrifuge  (p.  577).  It  gives  results 
accurate  to  within  0.2  per  cent,  of  fat.  It  is  a  simple  method  and 
the  manipulation  is  easy. 

Two  pipets  are  supplied  with  the  bottles,  one  of  5  c.c.  capacity; 
the  other  holding  i  c.c.  up  to  a  mark  on  the  lower  stem,  for  intro- 
ducing the  alcoholic  solution. 


EXAMINATION    OF    MILK 


575 


To  determine  fat  by  this  method  the  sample,  well  mixed, 
should  be  taken  from  the  middle  portion  of  the  nursing  or  milk- 
ing— as  the  first  milk  is  poorer  and  the  last  richer  than  the  average. 
Five  cubic  centimeters  of  the  sample  are  introduced  into  the  milk 
bottle  by  means  of  one  pipet;  i  c.c.  of  alcoholic  solution  (which 
consists  by  volume  of  amyl  alcohol,  37;  wood  alcohol,  13;  hydro- 
chloric acid,  50)  is  added  by  the  other,  and  the  bottle  shaken  by 
hand.  Then  by  means  of  the  large  pipet  strong  sulphuric  acid, 
specific  gravity  1.83,  is  added  little  by  little,  with  shaking,  until 
the  bottle  is  filled  to  the  brim.  When  whirled  in  the  centrifuge 
two  minutes,  the  fat  rises  to  the  neck  in  a  clear  yellowish  layer, 
and  can  be  read  off  in  direct  percentages.  If  the  level  of  the 


FIG.  90. — Werner-Schmid 
process. 


FIG.  91.— Milk  bottle  for 
centrifuge. 


FIG.  92. — Pipet  for 
milk. 


fat  should  be  below  the  zero  point  as  the  result  of  the  cooling,  a 
few  drops  of  water  should  be  added  to  raise  it.  Another  whirl 
of  the  centrifuge  will  carry  the  water  below  the  fat  layer  and 
lift  the  latter  to  the  desired  point.  If  the  milk  should  be  richer 
than  5  per  cent.,  add  5  c.c.  of  water  to  5  c.c.  of  milk,  mix 
thoroughly,  take  5  c.c.  for  analysis,  and  multiply  the  result  by  2. 

For  cream  add  20  c.c.  of  water  to  5  c.c.  of  cream,  mix,  take 
5  c.c.  for  analysis,  and  multiply  the  result  by  5. 

The  alcoholic  solution  can  be  kept  some  weeks.  If  it  turn 
dark,  a  fresh  mixture  must  be  made. 

By  Weighing. — To  determine  the  butter  by  the  gravimetric 
method,  10  gm.  of  milk  are  weighed  into  a  tared  dish  containing 
a  weighed  amount  of  dry  sand.  The  milk  is  evaporated  on  a 


CLINICAL    CHEMISTRY 


water-bath  and  last  on  a  water-oven,  with  constant  stirring.  The 
residue  is  washed  a  number  of  times  \vith  warm  ether 
or  petroleum  naphtha  of  specific  gravity  70°  Baume, 
and  the  washings  passed  through  a  small  filter.  The 
filtrates  are  all  received  in  a  tared  beaker  and  care- 
fully evaporated  to  a  constant  weight.  The  residue  is 
jat.  This  subtracted  from  the  amount  of  total  solids 
gives  the  solids  not  jat. 

Adams'  Method. — This  is  the  standard  process  in 
use  by  official  chemists  who  have  well-equipped  labo- 
ratories. The  milk  is  absorbed  by  strips  of  pure, 
fat-free  paper,  which  distributes  the  milk-fat  in  a  thin 
layer.  The  coiled  strip  is  dried  in  a  water  oven,  and 
then  placed  in  the  middle  chamber  of  a  Soxhlet  ex- 
tractor (Fig.  93).  The  tared  flask,  containing  75  c.c. 
of  ether,  is  heated  on  a  water-bath. 

Ether  vapor  condenses  in  the  upper  apparatus, 
flows  back  upon  the  coil  of  paper,  and  returns  to 
the  flask.  After  ten  such  washings  the  flask  con- 
taining the  ether  is  detached  and  connected  with 
a  condenser.  After  distillation,  the  fat  residue  is 
dried  in  an  air  oven,  cooled,  and  weighed. 


PRACTICAL  URINARY  EXAMINATION 

Ordinary  Examination.— As  this  section  is  concerned  with 
the  knowledge  which  has  value  to  the  medical  practitioner,  it  is 
deemed  best  to  limit  its  range  to  those  points  which  have  practical 
significance. 

A  good  working  plan  for  the  ordinary  analysis  need  not  in- 
clude more  than  the  following  procedures,  and  in  most  cases  less 
than  the  total  of  these  will  serve  every  requirement: 

Measurement  of  the  daily  quantity. 

Noting  the  color:  if  deep  yellow,  green,  or  brown,  testing  for 
biliary  pigment;  if  reddish,  smoky,  or  chocolate-hued,  testing  for 
hemoglobin.  (Plate  7.) 

Taking  the  reaction. 

Determination  of  specific  gravity  with  the  hydrometer. 

After  the  sediment  falls,  decanting  the  clear  part  and  examin- 
ing for  albumin  by  boiling  and  by  adding  acid — nitric,  picric,  or 
acetic.  If  greenish  flakes  form,  bile  pigment  is  to  be  looked  for; 
if  red-brown,  then  hemoglobin.  After  twenty-four  hours  noting 
the  height  of  albuminous  layer. 

Testing  for  glucose  by  Fehling's  and  by  Bb'ttger's  methods, 
with  calculation  of  the  amount. 


THE    URINE 


577 


Estimation  of  the  relative  amount  of  chlorids. 

Estimation  of  the  amount  of  urea. 

Noting  the  naked-eye  appearance  of  the  deposit  which  forms 
on  standing  for  several  hours.  Making  allowance  for  the  light 
cloud  of  epithelial  debris  sometimes  found  in  health,  a  sample 
voided  turbid  and  acid  points  to  urates  or  mucus  or  pus  or  blood; 
if  voided  turbid  and  alkaline,  it  points  to  phosphates.  (Plate  7.) 

Careful  examination  of  the  deposit  with  the  microscope,  using 
a  1  or  £  objective  and  an  eye-piece  giving  a  magnifying  power  of 
about  250  diameters.  The  search  should  be  made  for  phosphates, 
calcium  oxalate,  uric  acid,  urates,  epithelium,  pus,  tube-casts, 
spermatozoids,  blood-cells,  leucin,  tyrosin,  cystin,  organisms  such 
as  sarcinae,  the  molds,  and  bacteria;  and  in  addition  such  extra- 
neous substances  as  sometimes  enter  the 
bladder  by  fistula  from  the  rectum. 

For  minute  study  of  the  bacteria  it 
is  necessary  to  stain  the  sediment  and 
use  the  high  power  of  900  diameters 
obtained  with  immersion  lenses.  The 
illumination  should  be  by  substage  wide- 
angle  condensers.  If  the  absence  of 
organic  or  definite  crystalline  structure 
leave  a  doubt  as  to  the  nature  of  a 
deposit,  the  following  simple  tests  may 
prove  serviceable:  First,  warm  a  portion 
of  the  deposit  with  some  urine  in  a  test- 
tube:  if  it  clear  up,  then  the  urates  are 
present;  if  it  do  not  clear  up,  then  sus- 
pect phosphates.  Second,  warm  a  fresh 
portion  with  acetic  acid:  if  it  dissolve, 
phosphates  are  present. 

Precautions  as  to  the  Sample. — 

The  microscope  often  shows  substances 
which,  being  extra-urinary,  may  be 
broadly  described  as  dirt,  having  no 
significance  whatever.  Owing  to  ignor- 
ance or  carelessness  on  the  part  of  patient  or  nurse,  it  not  infre- 
quently happens  that  floating  dust  or  sweepings  or  fecal  matter 
get  into  the  vessel,  or  sometimes  an  unclean  bottle  may  make 
its  contribution.  Hairs,  cotton,  and  linen  fibers  may  be  mis- 
taken for  tube-casts,  while  such  objects  as  large  globules  of  free 
oil,  starch  granules,  and  vegetable  cells  are  obviously  extraneous. 
To  avoid  fallacies  it  is  well  to  enjoin  care  upon  the  patient  or 
nurse  to  have  the  container  sterilized  by  a  hot  solution  of  calx 
chlorinata.  The  urine  should  be  voided  into  a  well-cleaned 

37 


FIG.  94. — Hand  centrifuge. 


578  CLINICAL    CHEMISTRY 

chamber-vessel,  or,  better  still,  into  a  glass  collecting-jar  suffi- 
ciently large  to  hold  the  entire  daily  amount.  By  means  of  a 
clean  glass  funnel  about  8  fl.  oz.  should  be  transferred  to  a  bottle 
or,  if  in  hospital,  to  a  conic  glass. 

Before  taking  up  a  drop  of  the  deposit  with  the  pipet,  for 
examination  with  the  microscope,  sufficient  time  must  be  allowed 
for  the  sediment  to  collect.  As  a  rule,  this  will  require  that  the 
sample  should  stand  for  about  three  hours,  but  if  rotated  in  a 
centrifuge,  separation  will  occur  in  three  minutes.  If  the  amount 
of  the  spontaneous  deposit  be  small,  it  can  be  concentrated  by 
decanting  the  clear  fluid  and  using  the  centrifuge  upon  the  sedi- 
mentary portion. 

To  get  the  best  results  from  the  centrifuge  the  bearings  should 
be  lubricated,  violent  rotation  avoided,  and  the  arms  balanced 
by  carrying  equal  loads  of  the  fluid.  The  readiness  with  which 
urine  undergoes  change  is  a  noteworthy  fact.  The  liability 
varies  in  different  specimens.  Even  a  healthy  urine  may  in  a  few 
hours  after  micturition  increase  in  acidity,  owing  to  the  change 
of  the  common  soluble  urates  to  the  more  acid  and  less  soluble 
salts,  which  are  precipitated  along  with  more  or  less  free  uric 
acid. 

2(NaH2PO4)  +  Na2H2C5N4O3  =  2(Na2HPO4)  +  H4C5N4O3 

Acid  phosphate.  Sodium  urate.  Neutral  phosphate.  Uric  acid. 

The  destiny  of  the  urea  in  all  specimens  kept  several  days  in  a 
warm  place  is  to  be  converted  into  ammonium  carbonate  by  the 
growth  of  the  Micrococcus  urea  and  its  enzym,  urase. 

CO.N2H4       +       2H20       =        (NH4)2C03 

Urea.  Water.  Ammonium  carbonate. 

This  change  may  take  place  in  the  bladder  if  the  urine  be  re- 
tained too  long,  and  may  cause  grave  complications  in  vesical  dis- 
eases. 

The  urine  itself  becomes  turbid,  putrid,  and  irritating,  throwing 
down  a  deposit  of  phosphates  with  urate  of  ammonium. 

(NH4)2C03     +     2MgHP04     =     2(MGNH4P04)     +     H2CO3. 

Ammonium  carbonate.     Magnesium  phosphate.  Ammoniomagnesium 

phosphate. 

To  correct  this  tendency  in  cases  of  cystitis  it  is  customary  to 
wash  out  the  bladder  with  a  saturated  solution  of  boric  acid  or 
some  other  unirritating  antiferment. 

Preservative  Fluid. — The  sample  of  urine  should  be  ex- 
amined within  twelve  hours  after  micturition,  and  preferably 
within  three  hours,  merely  allowing  time  for  the  deposit  to  settle. 
When  it  is  desired  to  preserve  a  specimen  for  several  days,  it 
suffices  to  add  5  drops  of  chloroform  or  i  gr.  of  thymol  to  i  fl.  oz., 


THE    URINE 


579 


or  salicylic  acid,  about  3  gr.  to  J  pt.  of  urine.  This  will  not  pre- 
vent the  changes  of  structure  which  sometimes  take  place  in  blood- 
cells,  tube-casts,  and  renal  epithelium  when  the  urine  is  of  low 
density.  To  protect  these  from  alteration  the  density  must  be 
raised  by  adding  some  mineral  salt,  such  as  potassium  acetate, 
in  saturated  filtered  solution  containing  a  few  grains  of  salicylic 
acid.  A  sediment  can  be  preserved  indefinitely  by  first  giving  it 
several  washings  in  a  solution  of  chloral,  15  gr.  to  i  fl.  oz.  of 
water,  and  finally  setting  aside,  covered  with  the  same  solution. 
The  chloralized  specimen  can  be  mounted  permanently  for  the 
microscope.  Chloral  and  chloroform  each  reduces  Fehling's 
solution,  and  neither  should  be  used  if  the  urine  is  to  be  tested  for 
glucose.  For  saccharine  urine  thymol  is  preferred,  as  it  has  no 
reducing  action.  Boric  acid  is  a  good  preservative,  in  the  pro- 
portion of  5  gr.  to  4  fl.  oz.  of  urine.  Formaldehyd,  i  drop,  will 
preserve  a  pint  of  urine  one  week,  but  it  coagulates  albumin  if 
care  is  not  observed,  and  it  reduces  Fehling's  solution. 

Another  method  of  preserving  organized  sediments  is  to  wash 
three  times  with  normal  salt  solution,  and,  after  decanting,  put 
the  sediment  in  equal  parts  of  glycerin  and  water  with  2  per  cent, 
of  saturated  alcoholic  solution  of  thymol. 

Normal  Urine.— The  urine  of  health  is  a  clear  solution  in 
water  of  various  substances.  Some  of  these  impart  a  freely  acid 
reaction;  some  give  it  a  yellowish  color;  some  are  the  source  of 
its  characteristic  odor;  and  all  combined  raise  its  specific  gravity 
to  a  point  between  1015  and  1025.  The  proportion  of  its  constitu- 
ents are  not  constant  for  all  individuals,  nor  even  for  the  same 
person  taking  one  day  with  another;  indeed,  they  vary  hourly. 
In  making  a  statement  of  average  composition,  regard  is  had  to 
this  variable  character:  the  figures  which  follow  may  be  taken  as 
representing  the  average  amounts  in  round  numbers. 


Average  composition  of  normal  urine. 

Water 

Solids  as  tabulated  below    . 


Urea 

Uric  acid 

Hippuric  acid 

Creatinin 

Pigment,  mucus,  xanthin,    other  ex- 
tractives, etc 

Chlorids  of  potassium  and  sodium  . 
Sulphates  of  potassium  and  calcium  . 
Phosphates  of  potassium  and  sodium 
Phosphates  of  magnesium  and  calcium 


Percentage 
Composition. 

96.0 
4.0 

2.000 
O.O4O 
0.075 
0.075 

I.OOO 
1. 000 
O.I  10 

O.I2O 
0.080 


Grains 
per  diem. 

50  fl.  oz. 
1000  gr. 

500 
10 
15 
15 

170 
170 

40 

45 

30 


Grams 
per  diem. 

I2OO  C.C. 
60  gm. 

30.00 
.65 

•95 
-95 

10.00 
10.00 

2.60 
2.90 


Besides  these,  there  have  been  found  traces  of  indican,  phenol,  and  other 
aromatic  sulphates,  diastase,  oxalic,  and  lactic  acids,  unoxidized  sulphur,  and  phos- 
phorus. 


58o 


CLINICAL    CHEMISTRY 


¥ 


The  Quantity. — In  making  a  quantitative  determination  of 
any  constituent,  not  only  must  the  tested  sample  be  a  portion 
taken  from  the  total  mixed  urine  of  the  day,  but  the  daily  quan- 
tity of  the  urine  itself  must  be  known.  The  large 
collecting-jar  may  be  graduated  so  as  to  be  the 
measuring  vessel:  such  wide-mouthed  graduated 
jars  as  are  used  by  druggists  for  percolating  will 
serve  admirably,  though  the  common  glass  specie  jar 
is  about  as  good,  and  is  easily  obtained  anywhere. 
It  must  be  large  enough  to  hold  the  entire  daily 
discharge,  and  then  for  measuring  the  volume  a 
smaller  apothecary's  graduated  glass  can  be  used. 
The  wide  mouth  admits  of  the  introduction  of  the 
hand  for  the  thorough  washing  always  required 
before  beginning  the  daily  collection.  The  patient 
is  instructed  to  empty  his  bladder  at  a  given  hour, 
but  not  into  the  jar.  Afterward,  for  twenty-four 
hours,  the  urine  is  passed  into  the  one  jar,  which 
should  be  kept  in  a  cool  place,  and  at  the  given 
hour  the  last  contents  of  the  bladder  are  added  to 
it.  The  amount  should  then  be  noted,  and  about  8 
fluidounces  put  into  a  perfectly  clean  glass  bottle 
or  other  vessel  to  serve  as  a  sample  for  analysis. 
Practical  Import. — The  mean  daily  discharge  is 
1250  c.c.,  or  50  fl.  oz.,  or  3  pints.  In  drawing  con- 
clusions from  any  change  in  this  respect,  it  is  neces- 
sary first  to  note  that  even  in  health  there  may  be 
considerable  variation.  The  amount  voided  will  depend,  first, 
upon  the  amount  of  water  drunk;  it  will  be  affected  by  the  pro- 
portion of  water  lost  in  perspiration  and  the  quantity  retained 
in  the  tissues  as  necessary  for  nutrition.  These  factors  are  various 
in  different  men,  and  change  with  the  season  and  with  the  habit 
of  exercise.  It  is  compatible  with  health  in  some  for  the  daily 
discharge  to  reach  only  ij  pints,  and  at  times  for  it  to  go  as  high 
as  4  pints.  Making  allowances  for  these  physiologic  variations, 
the  urine  is  notably  scanty  in  certain  forms  of  Bright's  disease, 
in  cirrhosis  of  the  liver,  and  in  the  state  of  collapse  occurring 
in  cholera  or  the  pernicious  fever. 

By  anuria  is  meant  a  condition  in  which  the  urine  is  no  longer 
voided:  this  includes  suppression,  when  the  secretion  of  the  kid- 
ney is  suspended,  and  retention,  when  the  fluid,  although  secreted, 
is  retained  in  the  urinary  passages  by  mechanical  obstruction. 
Oliguria  is  the  term  applied  to  urine  scanty  from  low  pressure  of 
the  blood  or  other  cause. 

A  persistent  excess  of  the  aqueous  constituent,  without  a  cor- 


FIG.  Q5-— Per- 
centage tube. 


THE    URINE  581 

responding  increase  of  the  solids,  is  termed  hydruria.  This 
symptom  is  characteristic  of  diabetes  insipidus,  in  which  disease  the 
daily  discharge  may  be  more  than  8000  c.c.,  or  2  gal.,  while  the 
specific  gravity  sinks  to  1003  or  less.  Some  diuresis  occurs  in 
the  middle  period  of  atrophic  nephritis.  Hysteric  and  neurotic 
subjects  may  suffer  temporarily  from  a  too  copious  urinary  flow. 

By  polyuria  is  meant  an  excess  not  only  of  urinary  water,  but 
of  all  the  solid  constituents.  Beside  the  saccharine  diabetes, 
it  would  include  cases  of  azoturia,  in  which  the  urea  is  morbidly 
abundant,  and  the  phosphatic  diabetes  of  Teissier,  which  accom- 
panies an  excessive  tissue-waste. 

The  Color. — Normal  urine  is  amber-hued,  the  depth  of  color 
varying  as  the  proportion  of  coloring-matter  varies.  When  the 
volume  of  urine  is  low,  the  liquid  is  dense  and  the  color  deepens 
to  a  reddish  tint.  After  liberal  drinking,  followed  by  copious 
urination,  it  may  be  almost  as  colorless  as  water  itself. 

Beside  its  true  coloring  principles — urobilin,  urochrome, 
hematoporphyrin,  and  uro-erythrin — the  urine  contains  sulph- 
indoxylate  of  potassium  or  indican  (KC8H6NSO4),  a  colorless 
substance  which  forms  indigo-red  or  indigo-blue  by  the  action  of 
reagents.1  Its  presence  may  be  shown  by  Jaffe's  test  for  indican: 
add  to  two  inches  of  urine  in  a  test-tube  an  equal  volume  of 
fuming  yellow  hydrochloric  acid  and  one  or  two  drops  of  liquor 
sodae  chlorinatae  or  three  drops  of  solution  of  hydrogen  dioxid, 
or  (the  author's  modification)  a  piece  of  sodium  perborate  (Sche- 
ring)  as  big  as  a  pea.  There  is  danger  of  carrying  oxidation  too 
far,  changing  the  indigo-blue  to  yellow  isatin.  The  sodium  per- 
borate is  less  likely  to  do  this  than  the  chlorinated  soda  or  chlori- 
nated lime.  It  is  very  stable  in  all  climates  and  always  ready  for 
use,  which  can  not  be  said  of  either  of  the  chlorinated  preparations 
or  the  hydrogen  dioxid.  On  standing,  the  mixture  turns  bluish 
from  the  formation  of  indigo.  The  color  may  be  concentrated 
by  gently  shaking  with  i  c.c.  of  chloroform  or  of  ether  for  two 
minutes;  the  indigo  is  taken  up  by  it  and  on  standing  separates 
as  a  layer  which  is  blue  in  color  in  proportion  to  the  amount  of 
indican.  (Plate  8,  Fig.  8.)  With  normal  urine  there  is  a  pale 
blue  color.  Diseases  of  the  liver  and  bowels  which  cause  con- 
stipation thereby  favor  the  absorption  of  indol  from  the  fecal 
mass,  and  an  increase  of  its  derivative,  indican,  in  the  urine. 
This  increase  is  revealed  by  the  deeper  color  yielded  when  the 
above  test  is  applied.  A  fallacy  results  if  iodids  are  present 
through  ingestion,  as  the  free  iodin  dissolved  in  chloroform  gives 

1  Artificial  indicanuria  can  be  made  by  adding  to  normal  urine  horses'  urine,  or 
an  alcohol  extract  of  its  solid  residue.  The  urine  of  the  horse,  rich  in  indican,  can 
be  kept  ready  for  use  by  adding  to  it  chloroform,  five  drops  to  the  fluidounce. 


582  CLINICAL    CHEMISTRY 

a  rose  violet  color.  lodin  in  the  ether  layer  would  be  brown 
and  at  the  surface  (p.  145). 

The  urine  is  pale  yellow  in  the  free  flow  of  diabetes  and  after 
attacks  of  hysteria  or  epilepsy;  orange  red  from  the  elimination 
of  santonin  in  an  alkaline  medium;  reddish  naturally  after  full 
meals  with  small  potations,  after  severe  exercise  with  abundant 
sweating,  during  paroxysms  of  fever,  after  hemorrhage  into  the 
genito-urinary  tract,  and,  lastly,  after  the  administration  of  log- 
wood; brownish  from  the  condition  known  as  melanosis,  from 
hemoglobinuria,  and  from  the  administration  of  tar,  carbolic  acid, 
gallic  acid,  tannic  acid,  senna,  trional,  or  sulphonal.  Eating  of 
blue  candies  and  the  administration  of  methylene-blue  for  gonorrhea 
will  cause  green  urine.  In  jaundice  the  biliary  coloring-matter 
(q.  v.}  will  make  it  sulphur  yellow  or  olive-green. 

Practical  Import. — It  is  plain  that  excess  of  indican  would 
point  to  diseases  retarding  digestion  or  causing  constipation, 
though  it  has  been  found  in  cholera  and  all  forms  of  severe  cachexia. 
The  detection  of  foreign  coloring-matter  would  furnish  indications 
of  an  obvious  character  based  upon  the  nature  of  the  specific 
substance:  for  that  of  blood  consult  the  section  on  Hematuria; 
for  that  of  bile,  the  section  on  Biliary  Coloring  Matter  (p.  560). 

Urorosein  is  present  as  a  chromogen  in  very  small  amount 
in  normal  urine.  The  amount  is  increased  in  advanced  tubercu- 
lous disease,  malignant  diseases  of  the  abdominal  organs,  typhoid 
fever,  anemia,  and  diabetes.  It  changes  to  a  rosy  red  pigment 
after  the  addition  of  an  oxidizer,  such  as  nitric  acid,  as  a  test  for 
albumin.  When  the  rosy  tint  spreads  through  the  column  of 
urine  in  Heller's  test  for  albumin,  an  excess  of  urorosein  is  present. 
It  can  be  distinguished  from  indigo-blue  by  its  not  separating 
after  being  shaken  with  chloroform. 

Alkaptonuria. — A  peculiar  dark-brown  color  has  been  observed 
in  the  urine  of  certain  persons  and  certain  families.  It  is  attrib- 
uted to  the  presence  of  alkapton,  which  in  the  air  oxidizes  to  a 
darker  substance.  In  recent  years  cases  have  been  reported  which 
appear  to  be  congenital.  They  could  not  be  accounted  for  by 
special  foods  or  medicines  or  diseases,  the  condition  appearing  to 
persist  through  life  as  an  inherited  anomaly  of  nutrition.  The 
latest  view  is  that  the  material  of  alkaptonuria  is  a  substance 
called  homogentisic  acid  or  hydroquinone-acetic  acid,  C6H3(OH)2 
CH2COOH,  which  is  occasionally  mixed  with  uroleucic  acid. 
The  urine  containing  them  becomes  dark-colored  on  exposure 
to  the  air  and  reduces  Fehling's  solution.  Homogentisic  acid  is 
formed  in  the  small  intestine  as  a  cleavage  product  of  the  protein 
molecule,  but  that  found  in  the  urine  is  due  to  a  specific  derange- 
ment of  protein  metabolism. 


THE    URINE 


Specific  Gravity.— When  it  is  desired  to  .make  use  of  this 
property  in  determining  by  special  formulas  the  amount  of  urea 
or  of  sugar  in  solution,  it  is  best  to  take  the  observation  with  a 
delicate  Mohr  balance  or  with  the  specific-gravity  bottle.  A  bot- 
tle of  known  capacity,  say  of  1000  gr.,  is  counterpoised,  then 
filled  with  urine,  and  weighed  in  a  delicate  balance.  If  the  con- 
tents weigh  1025,  that  number  will  be  the  specific  gravity.  This 
operation  requires  apparatus  not  always  at  hand,  and  consumes 
time  not  always  at  the  disposal  of  the  physician.  For  ordinary 
purposes  it  suffices  to  take  the  specific  gravity  with  a  urinometer, 
which  is  a  spindle  hydrometer  for  liquids  heavier  than  water,  car- 
rying a  scale  ranging  from  1000  to  1060,  and  usually  made  to 
read  at  25°  C.  (77°  F.).  When  the  sample  of  urine  is  too  small 
in  amount  to  use  the  urinometer,  the  specific  gravity  of  i  c.c.  can 
be  taken  by  the  method  described  under  the  section  on  Specific 
Gravity  (p.  25). 

Method. — Fill  to  one-half  its  capacity  a  cylindric  vessel  having 
a  level  lip.  Gently  immerse  the  urinometer  and  carefully  fill  the 
cylinder  to  the  brim.  Take  the  observation  by  sighting  on  a 
level  with  the  surface  of  the  urine,  which  rises  slightly  above  the 
edge  of  the  glass.  Note  the  lower  surface  line  and  not  the  point 
to  which  the  liquid  is  attracted  up  the  side  of  the  scale. 

Practical  Import. — The  standard  of  health  is  usually  rated  as 
between  1015  and  1025,  but  very  free  use  of  beverages  may  cause 
it  to  fall  below  1010.  Under  ordi- 
nary conditions,  in  regard  to  the 
amount  of  fluid  ingested,  so  low  a 
density  would  point  to  diabetes  sim- 
plex or  to  Bright's  disease  with  defi- 
ciency of  urea.  When  the  record  is 
above  1030,  it  usually  denotes  sugar 
in  the  urine.  In  either  case  the  proper 
chemical  tests  would  solve  the  doubt. 

Total  Solids.— It  is  possible  to 
derive  valuable  conclusions  from 
roughly  estimating  the  solid  constit- 
uents of  the  urine  by  multiplying 
the  last  two  figures  of  the  specific 
gravity  with  Haeser's  factor,  2.60. 
This*  gives  parts  of  solids  per  thousand 

of  urine,  and  after  measuring  the  number  of  liters  passed  in 
twenty-four  hours,  furnishes  some  idea  of  the  efficiency  of  the 
kidney  at  the  time.  Another  rule  giving  grains  of  solids  is  to 
take  the  total  number  of  fluidounces  passed  in  the  day,  multiply 
by  the  two  last  figures  of  its  specific  gravity,  and  add  10  per  cent. 


FIG.  96. — Squibb's  urinometer. 


584  CLINICAL    CHEMISTRY 

Thus  if  50  fl.  oz.  be  passed,  the  specific  gravity  being  1015,  the 
total  solids  are  found  by  50X15  =  750  and  750  +  75  =  825  grains. 
The  average  amount  excreted  daily  by  a  healthy  male  is  70  gm., 
or  1 100  grains. 

Cryoscopy. — The  determination  of  the  freezing-point,  lowering 
of  the  urine  as  evidence  of  the  molecular  concentration,  is  a  help 
to  which  reference  has  been  made  in  another  place  (p.  39).  The 
method  is  invested  with  so  many  technical  difficulties  that  the 
practical  physician  contents  himself  with  deducing  the  activity 
of  the  kidneys  in  this  respect  empirically  by  multiplying  the  last 
two  figures  of  specific  gravity  carried  to  the  third  decimal  place, 
by  factor  0.075°  C.  The  sample  must  be  free  of  sugar  and 
albumin.  Thus,  if  the  specific  gravity  carefully  taken  gave  the 
last  two  figures  and  decimal  as  10.125,  tnen  10.125X0.075  = 
0.759°  C.,  which  is  less  than  the  normal  range  (1.2  to  2.3). 

Reaction. — In  noting  the  reaction  blue  and  red  litmus-papers 
may  be  used,  but  the  most  convenient  indicator  is  violet-colored 
neutral  litmus-paper.  Acids  turn  it  red  and  alkalis  blue.  A 
sample  of  the  total  daily  urine  of  health  should  turn  this  neutral 
paper,  or  even  the  blue  paper,  to  a  delicate  red.  This  shows  an 
acid  reaction  due  to  the  hydrion  dissociated  from  various  acid 
radicals  largely  organic  in  character. 

Occasionally  a  sample  is  encountered  which  turns  blue  litmus 
red  and  red  litmus  blue.  It  is  said  to  have  an  amphoteric  reac- 
tion, due  to  the  fact  that  the  urine  contains  both  the  acid  hydrion 
and  the  alkaline  hydroxidion  in  small  amounts. 

Test  for  Acidity. — Having  measured  into  a  beaker  100  c.c.  of 
urine  and  put  in  it  a  strip  of  red  litmus-paper,  the  sample  is 
titrated  with  decinormal  potassium  or  sodium  hydroxid  from  a 
graduated  buret.  Acidity  is  expressed  in  terms  of  oxalic  acid,  of 
which  0.0063  gm.  equals  i  c.c.  of  the  decinormal  potash  solution. 
If  12  c.c.  of  the  potash  neutralize  100  c.c.  of  the  urine,  then  the 
acidity  of  100  c.c.  is  12X0.0063  =  0.0756,  which  is  the  same  as 
0.756  parts  per  thousand.  Further  details  are  given  under 
Acidimetry  (p.  124). 

Owing  to  the  fact  that  the  acidity  of  the  urine  is  due  to  an 
acid  salt  which  is  imperfectly  saturated  by  the  testing  alkaline 
solution,  a  difficulty  arises  which  is  not  encountered  in  determining 
the  acidity  of  simple  acid  liquids.  Complex  methods  have  been 
devised  to  overcome  the  difficulty,  which  are  not  free  from  error, 
and  hence  the  ordinary  titration  given  above  is  preferred  as  being 
easy,  though  the  estimation  usually  figures  too  low. 

Sometimes  in  health  a  sample  representing  the  unmixed  urine 
secreted  during  the  first  or  second  hour  after  a  full  meal  is  alka- 
line or  neutral,  as  an  effect  of  the  preponderance  of  alkaline  salts 


THE    URINE  585 

in  the  food.  The  paper  made  blue  by  such  a  sample  retains  the 
blue  color,  thus  indicating  fixed  alkali — that  is,  alkaline  salts  of 
sodium  and  potassium. 

The  same  change  can  be  produced  at  will  by  the  repeated 
administration  of  large  doses  of  the  bicarbonates  or  citrates  of 
sodium  and  potassium,  as  in  the  alkaline  treatment  of  rheumatism. 
When  the  paper  is  turned  blue  by  the  volatile  alkali  ammonia,  we 
may  know  it  by  the  gradual  restoration  of  the  original  color  as 
the  ammonia  volatilizes.  A  characteristic  putrid  odor  attends 
this  reaction.  It  is  due  chiefly  to  the  ammonia  evolved  from 
ammonium  carbonate  resulting  from  the  decomposition  of  urea 
by  the  Micrococcus  urea. 

CON2H4       +       2(H2O)       =       (NH4)2CO3 

Urea.  Water.  Ammonium  carbonate. 

Practical  Import. — Persistent  alkalinity  due  to  fixed  alkali  is 
sometimes  found  in  persons  of  a  feeble  habit  of  body.  The 
change  in  reaction  lessens  the  solvent  power  of  urine  for  the 
earthy  phosphates,  which  in  consequence  are  precipitated  in  loose 
whitish  amorphous  particles.  These  do  not  tend  to  form  concre- 
tions. If  the  alkalinity  be  due  to  ammonia,  the  indication  is  very 
different.  The  ammoniacal  change  occurring  in  the  bladder  is  a 
concomitant  of  serious  vesical  mischief.  The  earthy  phosphates 
are  mixed  in  a  deposit  with  the  triple  phosphates  of  ammonium 
and  magnesium.  If  the  bladder  be  not  kept  well  washed  of  this 
deposit,  it  will  in  time  accrete  into  the  mixed  phosphate  gravel  or 
calculus.  In  every  case  of  incomplete  evacuation  of  the  bladder 
from  paralysis  or  obstruction  this  is  a  rock  ahead. 

It  remains  to  be  said  that  the  administration  of  acids,  unless  it 
be  benzoic  acid,  which  is  changed  to  hippuric  acid,  while  tending 
to  acidify  the  urine,  will  have  little  direct  effect  upon  the  reaction. 
The  strongest  acids,  given  in  usual  doses,  are  neutralized  before 
they  enter  the  circulation.  Whatever  power  they  have  over  the 
alkaline  urine  of  feeble  subjects  is  explained  by  the  increased  tone 
they  impart  to  digestion,  thus  removing  debility  and  anemia. 
Given  by  the  mouth,  they  exert  no  control  over  ammoniacal  urine. 

Urotropin  is  given  to  check  the  ammoniacal  fermentation,  which 
it  does  by  liberating  formaldehyd  in  the  urinary  passages.  Doses 
of  acid  sodium  phosphate  (NaH2PO4)  given  at  the  same  time  are 
eliminated  by  the  kidneys  and  will  lower  the  alkaline  reaction  by 
neutralizing  the  ammonia  in  the  urine. 

Phosphates. — The  urinary  phosphates  may  be  divided  into 
two  groups,  earthy  and  alkaline,  according  to  their  bases.  The 
total  daily  discharge  of  these  is  about  60  gr.  or  4  gm.,  the  two- 
phosphates  of  calcium  and  magnesium,  or  earthy  (MgHPO4-J- 


586  CLINICAL    CHEMISTRY 

Ca3(PO4)2),  constituting  one-third,  and  the  acid  sodium  and  potas- 
sium phosphates,  or  alkaline  (NaH3PO4+ KH2PO4),  the  other 
two-thirds.  The  presence  of  both  groups  is  shown  by  the  fol- 
lowing procedures: 

To  the  urine  in  a  test-tube  add  a  few  drops  of  potassium  hy- 
droxid  and  boil.  The  earthy  phosphates  are  thrown  out  and 
must  be  separated  by  nitration.  Then  to  the  nitrate  add  one- 
third  its  volume  of  magnesia  mixture.  The  precipitate  formed 
represents  the  phosphoric  acid  once  held  by  alkaline  bases,  now 
in  the  form  of  ammoniomagnesium  phosphate  (triple  phosphate).1 

In  order  to  estimate  approximately  the  total  phosphoric  acid, 
resort  may  be  had  to  Teissier's  method.  All  the  apparatus  needed 
is  a  glass  cylinder  graduated  in  the  cubic  centimeters  of  the  metric 
system.  Put  into  the  graduate  50  c.c.  of  urine  and  add  15  c.c. 
of  magnesia  mixture  (magnes.  sulph.,  parts  10;  ammon.  chlor.,  10; 
aq.  ammon.  fort.,  10;  water,  80).  Shake  well  and  set  aside  for 
twenty-four  hours.  All  the  phosphoric  acid  is  thrown  down  as 
ammoniomagnesium  phosphate,  a  dense  white  deposit.  At  the 
end  of  twenty-four  hours  note  the  number  of  cubic  centimeters 
occupied  by  this  sediment.  For  i  c.c.  there  are  0.3  gm.  per  liter, 
or  0.03  per  cent,  of  phosphoric  acid,  equivalent  to  0.6-0.7  gm-  °f 
phosphates  per  liter,  or  0.06-0.07  per  cent.  To  obtain  a  result 
in  terms  of  grains  to  the  fluidounce  multiply  by  4.55. 

The  centrifuge  determination  by  volume  is  made  by  filling  the 
percentage  tube  with  urine  to  the  10  c.c.  mark  and  adding  5  c.c. 
of  magnesia  mixture.  After  rotation  for  three  minutes  the  pre- 
cipitate falls  in  a  compact  stratum,  every  yV  c.c.  of  which  is  read 
as  i  per  cent,  of  phosphates  by  bulk.  The  phosphate  precipi- 
tate of  normal  urine  is  about  8  per  cent,  by  bulk.  Each  yV  c.c. 
of  the  sediment  is  estimated  to  equal  0.0225  per  cent,  by  weight 
of  P2O5.  Purdy  prefers  10  c.c.  of  urine,  2  c.c.  of  50  per  cent, 
acetic  acid,  and  3  c.c.  of  uranium  nitrate  (100  gr.  to  4  oz.).  In- 
vert several  times,  stand  aside  three  minutes,  then  rotate  three 
minutes  at  1200  revolutions  per  minute.  Read  off  bulk  per  cent, 
of  H(UO2)PO4,  of  which  TV  c.c.  =  P2O5,  0.04  per  cent.,  or  0.19 
gr.  to  i  fl.  oz. 

Volumetric  Method. — For  more  accurate  calculations  the  volu- 
metric method  will  serve.  The  standard  solutions  used  and  the 
indicators  can  be  had  of  all  first-class  druggists,  who  keep  formu- 
laries in  which  the  mode  of  preparation  is  given.  Put  50  c.c.  of 
urine  into  a  porcelain  capsule,  and  add  5  c.c.  of  a  saturated  solu- 

1  Artificial  phosphatic  urine  (for  students'  practice)  which  becomes  turbid  on 
boiling  can  be  made  by  adding  and  shaking  with  it  freshly  precipitated  calcium  car- 
bonate. Part  of  it  dissolves;  the  rest  can  be  filtered  off.  The  calcium  carbonate 
can  be  obtained  from  a  strong  solution  of  calcium  chlorid  by  the  addition  of  sodium 
carbonate,  leaving  the  calcium  chlorid  solution  in  excess  to  be  filtered  off. 


K  39r^>i'iK. 

pels  teoino<>  Vwiitf  edt  m  F^lfr-v- 

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nnot  sifl^Tfado  bm<  .Ited-dnujL 
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to 


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'mm  and  pot 
i  +  KH2P04),   the  otl 


i>*i  tube  add  a  few  drops  of  potassium  by- 

aft      T  he  earthy  phosphates  are  thrown   put   and 

rrl  hv   riltration.     Then  to.  the  filtrate  add  one- 

-ph'*ri<:  acid  once  held  by  alkaline  bases,  now 

num* magnesium  phosphate  (triple  phosphate).1 

Hpproximatelv  the  total  phosphoric  acid, 

PLATE  7. 

meters  of  the  metric 
URINARY  SEDIMENTS. 

The  most  important  macroscopic  varieties  of  urinary  sedi- 
ment are  represented  in  the  three  conical  glasses. 

FIG.  1.  Brick-dust  Sediment. — This  is  formed  only  of  jiric 
acid,  and  is  found  in  abundance  in  febrile  states,  after  active 
bodily  exertion,  etc.  It  dissolves  on  heating. 

FIG.  2.  Yellowish  Friable  Sediment. — This  may  consist  of 
phosphates  (soluble  on  addition  of  acid),  of  pus-corpuscles,  of 
renal  elements,  of  bacteria  (demonstrable  microscopically). 

FIG.  3.  Bloody  Sediment. — Demonstrable  by  Heller's  blood- 
test  (see  Plate  8,  Fig.  10),  as  well  as  by  microscopic  examination 
(renal  or  vesical  hemorrhage,  hemoglobinuria). 

Uric-acid  Sediment. 

FIG.  4.  Sodium  Urate,  in  small  yellowish  granules,  frequently 
adherent  to  other  elements,  especially  casts,  etc. 

FIG.  5.  Uric-acid  Crystals,  varying  in  color  from  yellow  to 
yellowish-brown,  in  large,  not  entirely  regular  plates,  in  whet- 
stone, dumb-bell,  and  comb-like  form  and  arrangement. 

Both  sediments  occur  only  in  urine  of  acid  reaction,  and  are 
precipitated  by  addition  of  acid.  They  dissolve  upon  addition 
of  potassium  hydroxid. 

(JAKOB.) 


PLATE  7. 


THE    URINE  587 

tion  of  sodium  acetate  containing  an  excess  of  acetic  acid.  Heat 
on  a  sand-bath  or  wire  gauze  until  boiling  begins,  and  then  from 
a  buret  slowly  add  about  2  c.c.  of  standard  solution  of  uranium 
acetate,  causing  a  precipitate  of  uranium  phosphate.  Stir  with  a 
glass  rod,  and  touch  its  wet  end  to  a  drop  of  solution  of  potas- 
sium ferrocyanid  on  a  white  plate.  A  red-brown  color  indicates 
that  too  much  standard  solution  has  been  used,  and  the  process 
must  be  repeated.  However,  this  is  not  likely  when  only  2  c.c. 
have  been  used.  If  no  red-brown  spot  appear,  continue  to  add 
from  buret  slowly,  and  after  the  addition  of  each  i  c.c.  stir  and 
touch  the  rod  to  the  ferrocyanid.  When  the  red-brown  spot 
appears,  read  off  the  number  of  cubic  centimeters  taken  from  the 
buret.  •  The  standard  solution  contained  31.1  gm.  of  uranium 
acetate  to  1000  c.c.  of  water,  equal  to  5  gm.  of  phosphoric  acid 
(P2O5).  If  1000  c.c.  =  5  gm.  P2O5,  then  i  c.c.  will  represent 
0.005  gm.  P2O5  in  the  50  c.c.  of  urine  employed.  The  terms  in 
percentage  can  be  obtained  by  multiplying  the  number  of  cubic 
centimeters  used  by  o.oi,  which  is  the  equivalent  of  0.005X2. 
To  get  grains  to  the  fluidounce  multiply  the  per  cent,  by  4.55. 

Practical  Import. — When  it  is  considered  that  the  phosphates 
of  the  urine  are  derived  only  in  part  from  the  waste  of  nervous 
tissue,  part  being  supplied  by  the  rest  of  the  body,  and  an  uncer- 
tain amount  coming  almost  directly  from  the  same  principles  in 
food,  it  will  be  easily  understood  why  the  quantitative  estimates 
so  far  have  proved  of  no  direct  value  to  the  clinician.  Their  sig- 
nificance depends  not  on  the  relative  proportion  in  the  sample, 
but  upon  their  state.  Any  amount,  large  or  small,  in  an  undis- 
solved  state  will  figure  as  a  deposit,  and  thereby  have  pathologic 
meaning  (PL  7,  Fig.  2). 

Phosphatic  Deposits. — It  has  been  said  above  that  the  phos- 
phates of  normal  acid  urine  are  held  in  clear  solution.  When 
the  urine  is  alkaline,  it  loses  its  solvent  powers  for  the  earthy 
phosphates,  and  throws  them  down  as  a  grayish-white  sediment 
made  of  colorless  granules,  which  show  no  tendency  to  aggregate 
into  masses  having  particular  shapes.  The  amorphous  urates 
form  into  groups  which  branch  somewhat  like  sprigs  of  moss. 
A  drop  of  acetic  acid  insinuated  under  the  cover-glass  will  clear 
away  the  phosphates,  but  not  the  urates.  If  the  alkalinity  be  due 
to  the  ammoniacal  fermentation  of  urea,  then  the  ammonia  reacts 
with  the  magnesium  phosphate  to  produce  the  white  crystalline 
deposit  of  ammoniomagnesium  phosphate — the  so-called  triple 
phosphate. 

2MgHP04    +    (NH4)2C03    =    H2C03    +    2MgNH4PO4 

Magnesium  phosphate.  Triple  phosphate. 


588 


CLINICAL    CHEMISTRY 


Usually  the  crystals  are  large  enough  to  be  seen  by  the  naked 
eye  as  minute  glittering  points,  which  the  microscope  resolves 
into  large,  bright  triangular  prisms  or  modified  forms,  sometimes 
feathery  and  sometimes  having  a  resemblance  to  a  coffin-lid  (see 

Fig-  97)- 

The  existence  of  these  mixed  phosphates  as  a  spontaneous 
deposit  at  the  time  of  micturition  usually  indicates  some  serious 
bladder  trouble,  such  as  cystitis  or  paralysis  or  stone.  Incom- 
plete evacuation  of  the  bladder  has  favored  the  ammoniacal  fer- 
mentation in  the  retained  urine.  If  the  condition  persist,  there 
is  ground  to  fear  that  eventually  a  phosphatic  concretion  will  form 
in  the  bladder  and  in  the  pelvis  of  the  kidney. 

Stellar  calcium  phosphate  is  sometimes  deposited  in  urine  which 
is  alkaline  from  fixed  alkali,  and  is  rarely  seen  except  in  some 


FIG.  97. — Triple  phosphate  and  spheres  of  ammonium  urate. 

general  disorder  of  serious  import.  Commonly  it  occurs  in  arrow- 
heads or  slender  wedges,  singly  or  gathered  in  star-like  masses 
(see  Fig.  98). 

Sulphates. — Sulphuric  acid  is  present  in  the  urine  partly  as 
preformed  mineral  sulphates,  and  partly  as  compounds  conjugated 
with  phenol,  indol,  and  skatol,  known  as  ethereal  or  aromatic  sul- 
phates (p.  430).  The  sulphates  of  the  alkaline  metals  and  mag- 
nesium (K2SO4  +  Na2SO4  +  MgSO4),  which  are  eliminated  by  the 
urine  to  the  extent  of  about  2  gm.  or  30  gr.  daily,  are  derived  chiefly 
from  the  diet  and  partly  from  the  oxidation  of  the  protein  principles 
of  the  tissues  and  fluids. 

These  mineral  salts  make  up  nine-tenths  of  the  total  sulphates; 
the  remaining  one-tenth  is  in  the  form  of  ethereal  compounds  of  con- 
jugate acids,  such  as  the  phenol-,  cresol-,  indoxyl-,  and  skatoxyl- 


THE    URINE 


589 


sulphates  of  potassium.  These  are  products  of  protein  putre- 
faction, absorbed  from  the  intestines  and  eliminated  by  the  kidney. 
Their  normal  amount  varies  between  0.12  and  0.3  gin.  Any  in- 
crease is  roughly  indicative  of  intestinal  indigestion  (p.  581). 

Determination  of  Total  Sulphates. — Mix  urine,  100  c.c.,  with 
20  c.c.  of  5  per  cent,  barium  chlorid  and  10  c.c.  of  hydrochloric 
acid.  Boil  half  an  hour;  filter  the  white  precipitate  of  barium 
sulphate;  collect,  dry,  and  weigh.  For  100  parts  of  the  BaSO4 
calculate  42  parts  of  absolute  H2SO4,  or  34.3  parts  of  sulphuric 
anhydrid,  SO3. 

Determination  of  Ethereal  Sulphates  Only.— These  can  be 
determined  by  the  following  procedure:  Take  of  urine  200  c.c.  and 
mix  with  an  equal  volume  of  barium  chlorid  made  alkaline  with 
barium  hydrate.  Filter  off  the  precipitate  through  dry  paper. 


FIG.  98. — Stellar  calcium  phosphate. 

The  clear  filtrate  contains  the  ethereal  sulphates,  which  are  not 
precipitable  by  barium  chlorid  until  they  are  decomposed  by  boiling 
with  hydrochloric  acid.  Take  200  c.c.  of  this  filtrate,  representing 
100  c.c.  of  urine  and  20  c.c.  of  hydrochloric  acid,  and  boil  ten 
minutes.  Filter,  dry  the  precipitate,  and  calculate  H2SO4  as  stated 
above.  The  easiest  clinical  test  is  the  one  known  as  J  a  fit's  test 
for  indican  (see  Indican,  p.  581).  In  general  the  indican  reaction 
is  deep  in  color  in  proportion  to  the  total  excretion  of  ethereal  sul- 
phates (p.  487). 

Centrifuge  Estimation  of  Mineral  Sulphates.— Into  the 
graduated  tube  put  10  c.c.  of  urine  and  5  c.c.  of  barium  chlorid 
solution  (BaCl2,  4  parts;  HC1,  i  part;  H2O,  16  parts).  Invert 
several  times,  set  aside  for  three  minutes,  and  rotate  three  minutes. 
Read  each  -^  c.c.  of  sediment  as  percentage  by  bulk,  the  normal 


5QO  CLINICAL    CHEMISTRY 

amount  being  0.8  per  cent.  Every  iV  c.c.  of  sediment  represents 
0.25  per  cent,  of  SO3,  or  i.i  gr.  to  i  fl.  oz. 

Practical  Import. — Although  their  amount  is  increased  by  fever 
and  other  wasting  pathologic  conditions,  the  increase  is  not  strictly 
proportional.  The  effect  of  diet  is  not  easily  calculated,  nor  can 
exact  allowance  be  made  for  the  uneven  action  of  the  eliminative 
process.  On  these  accounts  it  is  of  little  value  to  the  clinician  to 
determine  the  amount  of  the  mineral  sulphates.  When  the  blue 
indican  reaction  is  strong,  it  shows  that  the  ethereal  sulphates  are 
increased,  and  we  find,  at  the  same  time,  symptoms  of  impaired 
intestinal  digestion,  such  as  pains,  flatulence,  constipation.  Before 
operation  for  cancer  of  the  intestines  it  is  desirable  to  know  if  the 
intestines  are  empty.  This  is  indicated  by  the  decline  of  conjugate 
sulphates  in  the  urine  to  a  mere  trace. 

Chlorids. — Nearly  200  gr.,  or  8  to  12  gm.,  of  these  salts  (Nad 
and  KC1)  are  discharged  daily  by  the  urine.  They  are  greater 
in  amount  than  the  sulphates  and  phosphates  together.  In  testing 
for  them  the  sample  is  first  acidulated  with  a  few  drops  of  nitric 
acid,  so  as  to  hold  the  phosphates  in  solution.  Then,  drop  by  drop, 
a  strong  solution  of  silver  nitrate  (3j-fSj)  is  added  so  long  as  white 
curds  of  silver  chlorid  are  precipitated.  If  the  amount  of  chlorids 
is  less  than  normal,  then,  instead  of  heavy  curds  being  formed,  the 
urine  becomes  milky  or  cloudy.  A  rough  estimate  can  thus  be 
made  as  to  any  marked  deviations  from  the  normal  quantity.  To 
make  a  volumetric  determination  put  10  c.c.  of  urine  into  a  beaker 
and  add  50  c.c.  of  water  and  8  to  10  drops  of  neutral  potassium 
chromate.  From  a  buret  let  fall  by  drops  the  standard  solution  of 
silver  nitrate  while  stirring  with  a  glass  rod.  As  soon  as  the  urine 
in  the  beaker  becomes  permanently  orange  red  throughout,  read 
off  the  cubic  centimeters  used,  subtracting  i  c.c.  for  excess  of 
silver  solution. 

As  the  standard  solution  contained  of  AgNO8  29.06  gm.  per 
1000,  equal  to  10  gm.  Nad,  so  i  c.c.  =  o.oi  Nad  in  the  10  c.c. 
used,  or  o.i  per  cent.  To  get  the  percentage  of  chlorids  mul- 
tiply the  number  of  cubic  centimeters  noted  by  10;  to  get  the 
number  of  grains  to  the  fluidounce  multiply  the  cubic  centimeters 
by  45.57.  Thus,  if  13  c.c.  were  used,  12  c.c.  would  be  counted. 
If  i  c.c.  =  0.01  NaCl,  then  12  =  0.12,  or  1.2  per  cent.  While  this 
method  may  be  considered  sufficiently  accurate  for  clinical  pur- 
poses, it  fails  in  exactness  when  the  urine  is  high-colored,  albumin- 
ous, or  putrid. 

The  centrifuge  determination  by  volume  is  made  with  urine 
previously  filtered  or  rotated  until  clear.  The  clear  urine  to  the 
amount  of  10  c.c.  is  put  into  the  percentage  tube,  then  acidulated 
with  i  c.c.  of  nitric  acid,  and  finally  4  c.c.  of  strong  solution  of 


THE    URINE 


591 


silver  nitrate  is  added  (3j-f3j).  Stand  aside  three  minutes  after 
several  inversions.  After  rotating  for  three  minutes  the  precipi- 
tated chlorids  are  read  off  as  i  per  cent,  by  bulk  for  every  -fa  c.c. 
The  measure  of  normal  chlorids  is  from  10  to  12  per  cent. 

Every  fa  c.c.  represents  0.13  per  cent,  of  Nad  by  weight,  or 
0.62  gr.  to  i  fl.  oz.  The  normal  proportion  of  Nad  by  weight  is 
i  per  cent. 

Practical  Import. — It  has  been  observed  that  in  acute  febrile 
diseases,  such  as  pneumonia,  pleurisy,  and  rheumatism,  at  the 
stage  in  which  exudations  are  forming,  the  chlorids  are  retained 
in  the  body  while  they  diminish  in  the  urine.  In  cases  of  pneu- 
monia with  extensive  exudation  they  may  totally  disappear.  Their 
reappearance  may  be  expected  when  resolution  sets  in  and  the 
fever  declines.  The  missing  quantity  is  made  up  by  excess  in 
convalescence. 


FIG.  99. — Calcium  oxalate. 


Calcium  Oxalate. — While  oxalic  acid  is  usually  stated  to  be  a 
constituent  of  the  urine,  the  amount  should  not  exceed  what  is 
called  a  trace.  Its  combination  with  calcium  is  soluble  to  such  an 
extremely  small  amount  by  the  aid  of  the  acid  phosphates  that 
anything  more  than  a  trace  appears  as  a  spontaneous  deposit.  Its 
naked-eye  characters  are  not  distinctive  from  those  of  mucus  or 
epithelial  debris.  Its  crystals  are  very  minute,  and  call  for  the 
microscope  to  make  out  their  form.  It  takes  two  different  shapes, 
more  commonly  occurring  as  octahedra,  which  appear  as  bright 
squares  with  diagonal  cross-lines,  like  envelops,  and  sometimes, 
though  rarely,  showing  as  very  small  dumb-bells,  or  forms  re- 
sembling an  hour-glass  (see  Fig.  99). 

Practical  Import. — It  is  probable  that  a  diet  of  subacid  fruits 
and  vegetables,  like  rhubarb  or  pie-plant,  containing  oxalates  will 


592  CLINICAL    CHEMISTRY 

furnish  directly  oxalic  acid  to  the  urine.  As  it  is  a  laboratory 
product  of  oxidation  changes  in  fats,  sugars,  and  starches,  it  is 
easy  to  see  why  impaired  digestion  or  retarded  metabolism  may 
be  the  source.  Although  appearing  sometimes  without  assign- 
able cause,  it  usually  attends  conditions  to  be  remedied  by  plain 
diet,  temperance,  and  outdoor  life.  It  is  frequently  incidental  to 
the  gouty  habit.  The  deposit  may  be  transient,  scanty,  and  un- 
important, or  it  may  be  persistent  and  more  abundant,  and  on 
these  accounts  serious,  as  indicating  a  disposition  to  the  formation 
of  a  concretion  of  the  kind  known  as  the  mulberry  calculus.  These 
calculi  are  so  rough  as  to  cause  frequent  bleeding  in  the  bladder, 
the  blood  imparting  a  dark  color. 

Urea. — As  it  is  the  chief  solid  constituent  of  the  urine,  urea  is 
also  the  most  important  physiologically  as  well  as  pathologically. 
Its  chemical  formula,  CO(NH2)2,  shows  its  nitrogenous  character, 
and  presents  the  view  held  as  to  its  nature,  a  carbonyl  diamid 
(p.  193).  The  amount  excreted  daily  is  nearly  500  gr.,  or  40  gm., 
equal  to  all  the  other  solids  put  together;  from  which  it  will  be 
seen  what  a  conspicuous  role  is  played  by  it  as  a  compound  rep- 
resenting the  waste  of  the  protein  or  nitrogenized  principles. 
Neutral  in  reaction,  freely  soluble  in  water  and  alcohol,  though 
insoluble  in  ether,  it  is  without  color  or  odor,  but  has  a  bitter  taste. 
In  its  chemical  behavior,  while  it  does  not  affect  litmus,  at  times 
it  is  basic,  and  then  again  it  may  act  in  a  compound,  as  acids  do. 
From  concentrated  solutions  it  can  be  crystallized  slowly  in  quad- 
ratic prisms  beveled  at  the  ends  (pp.  200,  492). 

If  the  urine  be  evaporated  in  a  water-bath  to  the  consistence 
of  syrup  and  nitric  acid  added  to  it,  the  crystals  of  urea  nitrate 
should  soon  form  in  rhombic  plates  or  hexagonal  scales.  Failure 
to  precipitate  crystals  under  these  conditions  (when  the  urine  has 
been  evaporated  one-half)  would  indicate  deficiency  in  the  pro- 
portion of  urea  in  the  sample. 

Urea  is  decomposed  by  boiling  the  urine;  by  the  action  of  fuming 
nitric  acid;  by  free  chlorin  or  bromin,  or  certain  of  their  compounds, 
such  as  sodium  hypochlorite  and  hypobromite: 

N2H4CO    -f-    3NaBrO    =    3NaBr    +     2H2O    +    2N    +    CO2. 

Urea.  Sodium  hypobromite. 

The  above  equation  represents  the  reaction  of  urea  with  sodium 
hypobromite.  As  stated,  it  yields  sodium  bromid,  water,  free  nitro- 
gen, and  carbon  dioxid.  By  using  with  the  sodium  hypobromite 
an  excess  of  alkali,  such  as  sodium  hydroxid,  as  in  Knop's  fluid,  the 
CO2  is  fixed  in  the  solution  as  carbonate,  and  the  only  gas  escap- 
ing is  free  nitrogen.  The  equation  for  this  reaction  is  as  follows: 

N2H4CO  +  3NaBrO  +  2NaHO  =  3NaBr  +  Na2CO3  +  4H2O  +  N2. 


THE    URINE 


593 


Hypobromite  Method. — Different  forms  of  apparatus  have 
been  devised  to  measure  the  free  nitrogen  evolved  by  the  sodium  hy- 
pobromite.  The  form  usually  employed  is  known  as  Russell  and 
West's  or  as  Apjohn's.  The  urine  and  the  reagent  are  mixed 
and  the  effervescing  gas  is  delivered  by  a  rubber  tube  at  the  top 
of  a  graduated  cylinder  open  at  the  bottom  and  immersed  in 
water  serving  as  a  gasometer.  This  collecting  cylinder  may  be 
graduated  in  cubic  centimeters,  and  in  such  a  case  the  determina- 
tion will  be  made  on  the  basis  of  i  c.c.  of  nitrogen  evolved  for 
0.0027  gm.  of  urea.  Sometimes  it  is  graduated  to  read  percent- 
age, on  the  principle  that  5  c.c.  of  a  2  per  cent,  solution  of  urea 
will  yield  37.1  c.c.  of  nitrogen.  As  solutions  of  sodium  hypobro- 
mite  are  unstable,  in  order  to  insure  an  accurate  result  it  is  best 
to  prepare  them  freshly,  according  to  the  formula  of  Knop,  and  if 
any  great  interval  must  elapse  between  successive  determinations, 
it  is  best  to  keep  the  reagent  in  two  parts,  each  of  which  is  stable. 
Knop's  solution  is  made  by  dissolving  100  gm.  of  sodium  hydroxid 
in  250  c.c.  of  water.  This  should  be  kept  in  a  separate  bottle, 
with  a  stopper  of  rubber  or  of  glass  coated  with  paraffin.  When 
the  fluid  is  to  be  used,  measure  out  15  c.c.,  and  mix  with  it  i  c.c. 
of  bromin.  Care  must  be  observed  in  pouring  the  bromin,  as 
the  vapor  is  highly  irritating  to  the  eyes  and  air-passages. 

Squibb's  Fluids. — Squibb  uses  two  fluids,  one  (a)  a  solution  of 
sodium  hydroxid,  100  gm.  in  250  c.c.  of  water;  the  other  (b)  a 
solution  of  bromin  and  potassium  bromid,  made  as  follows: 
Weigh  the  contents  of  a  i-ounce  bottle  of  bromin  by  deducting  the 
weight  of  the  bottle  empty  from  the  weight  when  filled.  Pour 
the  bromin  into  a  bottle  of  300  c.c.  or  10  fl.  oz.  capacity.  Add  to 
the  bromin  an  equal  weight  of  potassium  bromid  and  as  many 
cubic  centimeters  of  water  as  eight  times  the  number  of  grams  of 
bromin.  When  used,  mix  (a)  and  (b)  in  equal  parts. 

The  procedure  is  as  follows:  First,  immerse  the  graduated 
gasometer  tube  upright  until  the  water  rises  in  it  to  the  zero  mark. 
Measure  the  16  c.c.  of  Knop's  fluid  into  the  flask,  and  then,  by 
means  of  forceps  or  a  string  (to  hold  it  upright,  so  as  not  to  spill), 
put  in  a  short  test-tube  containing  5  c.c.  of  urine.  Close  the  flask 
tightly  with  a  rubber  stopper  carrying  a  gas-tight  rubber  connection 
with  the  graduated  gasometer.  Now  tip  the  flask  so  as  to  gradually 
pour  out  the  urine  into  the  surrounding  hypobromite.  By  perform- 
ing this  slowly  there  is  greater  certainty  that  the  CO2  will  be  held 
fixed  by  the  alkali,  and  that  nitrogen  only  shall  pass  into  the  meas- 
uring vessel.  After  waiting  ten  minutes  to  complete  the  decompo- 
sition of  urea,  raise  the  gasometer  so  that  the  water  within  is  on  a 
level  with  that  outside,  and  read  off  the  cubic  centimeter  of  nitrogen 
collected  (or  the  percentage  of  urea  if  the  tube  be  so  graduated). 
38 


594  CLINICAL    CHEMISTRY 

The  computation  is  0.0027  of  urea  in  the  5  c.c.  of  urine  used 
for  each  cubic  centimeter  of  nitrogen.  Thus,  if  the  gasometer 
records  7  c.c.  of  nitrogen,  then  there  were  7X0.0027  =  0.0189 
gm.  of  urea  in  the  5  c.c.  of  urine.  Multiplying  by  20  to  get  the 
percentage,  we  have  0.0378  per  cent. 

To  calculate  grains  to  the  fluidounce,  multiply  the  percentage 
by  4.55.  If  the  apparatus -be  stated  to  have  been  graduated  at 
65°  or  70°  F.,  reasonable  accuracy  in  results  can  be  obtained 
be  taking  the  observation  in  an  apartment  at  or  near  that  temper- 
ature. The  variation  of  temperature  indoors  would  then  affect 
the  volume  of  gas  so  little  as  to  be  of  small  moment  in  clinical 
observations.  In  such  cases  differences  of  barometric  pressure 
might  be  ignored  without  seriously  affecting  the  calculation.1 

Hinds-Doremus  Ureometer. — A  form  of  apparatus  was  devised 
by  W.  H.  Greene,  which  consisted  of  a  single  tube  for  the  reaction 
and  the  measurement  of  nitrogen.  The  most  convenient  modifi- 
cation of  Greene's  idea  is  that  known  as  the  Hinds-Doremus 
ureometer  (Fig.  100).  It  consists  of  a  bulb  with  an  upright  tube 
(a)  graduated  so  that  each  of  the  smallest  divisions  represents 
o.ooi  gm.  of  urea  in  the  urine  used.  Connected  with  the  lower 
portion  of  the  tube  is  a  ground-glass  stop-cock  (b)  which  sup- 
ports a  smaller  upright  tube  (c)  graduated  with  a  capacity  of 
2  c.c.  Closing  the  cock  (b),  the  bulb  is  filled  with  Knop's  or 
Squibb's  fluid  diluted  one-half  (see  p.  594),  or  liquor  soda  chlo- 
rinatcz.  The  opening  is  then  closed  with  the  thumb  and  the  tube 
inverted  so  as  to  fill  with  the  reagent.  When  restored  to  an  up- 
right position,  the  smaller  tube  (c)  is  filled  to  the  zero  mark  with 
urine.  The  cock  (b)  is  turned  slowly,  so  as  to  admit  gradually 
i  c.c.  of  the  urine  to  the  measuring  tube  (a).  In  about  fifteen 
minutes  the  gas  nitrogen  ceases  to  collect  at  the  top  of  the  tube 
and  the  level  may  be  read  off  as  so  many  grams  of  urea  in  the  i 
or  2  c.c.  of  urine  used. 

If  the  reading  was  0.015  and  the  amount  of  urine  used  was 
i  c.c.,  then  multiplying  by  100  gives  1.5  per  cent,  of  urea.  A 
more  correct  reading  is  obtained  by  submerging  the  whole  appa- 
ratus in  a  pitcher  or  beaker  until  the  water  outside  and  the  hypo- 

1  Some  gas-measuring  tubes  are  graduated  to  be  read  at  a  temperature  of  o°  C. 
(32°  F.)  and  barometric  pressure  of  30  in.  or  760  mm. 

Owing  to  the  susceptibility  of  gas-volumes  to  variations  of  heat  and  pressure,  to 
ensure  perfect  accuracy,  a  correction  must  be  made  according  to  the  following 
formula : 

V>  = V(t>-v* in  which 

760  (1+0.00366^) 

Vr  =  volume  required ;    V=  volume  observed ; 

b    =  barometer  in  mm. ;  w  —  tension  of  aqueous  vapor ; 

T  =  observed  temperature,  Centigrade. 


THE    URINE 


595 


bromite  inside  are  on  a  level.  As  the  instrument  is  graduated 
experimentally  at  19°  C.  (65°  F.),  no  correction  is  usually  neces- 
sary for  temperature.  Ordinary  variations  of  atmospheric  pres- 
sure may  be  ignored  when  the  results  are  intended  for  clinical  use. 
Immediately  after  using,  the  tube  should  be  washed  with  alcohol. 

Although  sufficiently  accurate  for  clinical  purposes,  the  hypo- 
bromite  process  liberates  only  93  per  cent,  of  the  urea  nitrogen, 
part  of  the  deficiency  being  made  up  from  the  creatinin,  hippuric 
acid,  and  the  purin  bodies.  For  exact  studies  these  other  nitrog- 
enous substances  are  first  removed  by  the  Mbrner  process  of 
precipitation,  by  adding  a  mixture  of  barium  chlorid  and  hydrate 
to  the  urine  along  with  ether  and  alco- 
hol. The  filtrate  of  ether-alcohol  hold- 
ing urea  in  solution  is  concentrated  by 
heat  to  get  rid  of  ammonia,  and  is  then 
submitted  to  the  Kjeldahl  process  for 
determining  nitrogen  (p.  365). 

Practical  Import. — Urea  being  freely 
soluble  never  figures  as  a  spontaneous 
urinary  deposit.  Morbid  conditions 
causing  increased  tissue  waste  will  al- 
ways run  up  the  proportion  of  this  prod- 
uct. In  fevers  and  divers  inflamma- 
tions the  amount  is  increased  in  the 
early,  or  forming,  stage  and  then  de- 
clines with  the  febrile  movement.  In 
all  acute  diseases,  as  well  as  in  phthisis, 
the  rate  of  excretion  rises  and  falls  with 
the  exacerbations  of  fever.  In  acute  yellow  atrophy  of  the  liver  at 
first  it  may  be  increased,  but  soon  it  declines  notably,  and  in  the  end 
may  disappear  utterly.  There  is  apt  to  be  a  marked  lessening  in 
the  proportion  when  acute  or  chronic  Bright's  disease  affects  the 
eliminating  powers  of  the  kidney.  Eventually  this  brings  on  the 
very  dangerous  symptoms  of  uremia.  When  urine  is  retained  in 
the  bladder  from  diseases  which  interfere  with  complete  evacuation, 
the  ready  conversion  of  urea,  which  is  locally  innocuous,  into  irritat- 
ing ammonium  carbonate  causes  it  to  figure  as  a  pathologic  factor. 

Uric  Acid. — The  chemical  formula  of  uric  acid,  C5H4N4O3, 
shows  its  derivation  from  the  nitrogenous  principles  of  the  body. 

Its  structural  formula  (p.  488)  as  a  trioxypurin  shows  that  it  is 
formed  through  oxidation  of  purin  groups.  Much  of  it  is  changed 
to  urea  in  the  liver,  kidneys,  and  muscular  tissue,  but  some  is  elimi- 
nated in  the  urine.  While  it  resembles  urea  in  containing  nitrogen 
and  in  its  origin,  it  is  very  unlike  it  in  other  respects.  The  average 
daily  quantity  excreted  is  only  10  gr.  or  0.7  gm.  Taking  40,000 


FIG.  ioo. — Hinds'  modification  of  the 
Doremus  ureometer. 


5p6 


CLINICAL    CHEMISTRY 


a  i,6 

11.4 


0.199 
0,202 
0,205 
0.209 
0.211 
0.215 
0.218 
0.221 
0.226 
0.228 
.0.231 


7,8 


parts  of  water  for  its  solution,  it  may  be  considered  as  practically 
insoluble  in  that  medium,  though  dissolving  in  1000  parts  of  blood- 
serum  and  freely  soluble  in  the  alkalis  and 
solutions  of  the  alkaline  carbonates.  A  trace 
of  the  free  acid  may  be  discovered  in  normal 
urine,  but  anything  more  than  a  mere  trace  will 
be  precipitated,  and  then  it  has  pathologic 
significance.  The  10  gr.  eliminated  daily  are 
not  free,  but  combined  with  sodium  and  potas- 
sium as  urates,  soluble  at  ordinary  temperatures 
by  the  help  of  the  alkaline  phosphates,  which 
prevent  decomposition  by  the  acid  salts  of  the 
urine.  A  dense  urine  kept  long  enough  to  pass 
into  the  acid  fermentation  will  throw  out  the 
uric  acid  along  with  acid  sodium  urate  and 
calcium  oxalate.  The  acid  can  be  separated 
from  its  bases  artificially  by  adding  10  parts 
of  hydrochloric  acid  to  100  of  urine.  After 
standing  forty-eight  hours  minute  brown  crys- 
tals of  uric  acid  will  fall.  To  collect  these,  and 
thereby  obtain  an  approximate  estimate  of  the 
amount,  the  supernatant  urine  should  be  de- 
canted, the  sediment  washed  by  stirring  it  with 
30  parts  of  water,  and  then  collected  by  throw- 
ing them  with  the  water  upon  a  weighed  filter. 
After  drying  the  filter  with  its  sediment  in  a 
hot-air  chamber  it  can  be  weighed  again,  and 
then,  allowing  for  the  weight  of  the  paper,  the 
weight  of  the  crystals  can  be  ascertained. 

Ruhemann's  Uricometer  for  the  Rapid 
Estimation  of  Uric  Acid. — This  test  is  based 
on  the  principle  that  a  brown  iodin  solution  is 
neutralized  by  a  certain  proportion  of  uric  acid 
until  the  brown  color  vanishes  completely.  Its 
author  has  calculated  the  exact  amount  of  iodin 
and  potassium  iodid  necessary  to  determine  the 
percentage  of  uric  acid  in  a  given  amount  of 
urine,  and  on  that  basis  has  constructed  a 
graduated  scale. 

Fill  the  dry  glass  tube  shown  in  diagram 
(Fig.  101)  to  the  lowest  mark  5  with  carbon  bi- 
sulphid.  The  lowest  part  of  the  convexity 
(double  meniscus)  has  to  be  even  with  mark 
S.  A  solution  consisting  of  1.5  gr.  iodin,  1.5 
gr.  potassium  iodid,  15  gr.  absolute  alcohol,  and  185  gr.  dis- 
tilled water  is  added  as  much  as  will  fill  up  to  the  mark  /,  as 


1,63 


FIG.  101. — Ruhemann's 
uricometer. 


THE    URINE  597 

shown  in  the  illustration.  Then  add  the  urine  to  the  mark 
2.45  (2.6  c.c.).  Close  the  tube  with  the  glass  stopper  and 
shake  well,  when  the  carbon  bisulphid  will  become  of  a  dark 
copper-brown  color.  After  adding  more  urine  under  continued 
shaking  the  carbon  bisulphid  will  absorb  all  free  iodin  and  the 
mixture  will  look  like  urine.  Slowly  adding  more  urine  will  change 
the  yellow  foam,  created  by  shaking,  into  white  foam.  The  color 
of  the  carbon  bisulphid  will  turn  pink  after  a  while.  Should  this 
color  remain  the  same  after  the  apparatus  has  been  reversed  and 
shaken  repeatedly,  add  another  drop  of  urine  and  keep  on  adding 
and  shaking  until  only  a  slightly  reddish  coloration  of  the  carbon 
bisulphid  remains.  Now  shake  again  vigorously,  and  the  carbon 
bisulphid  will  turn  porcelain  white,  and  the  urine  will  look  like 
cloudy  whey. 

Precaution. — Stop  adding  urine  as  soon  as  the  carbon  bisul- 
phid shows  only  a  slightly  reddish  tint,  because  this  will  disappear 
entirely  after  repeated  shakings.  The  test  is  finished  when  the 
indicator  appears  snow-white,  a  sign  that  all  iodin  has  been  neu- 
tralized by  the  urine. 

To  get  rid  of  the  remaining  foam  move  the  tube  a  few  times 
slowly  to  a  horizontal  position,  then  open  the  stopper  a  little,  to 
allow  all  liquid  to  settle  in  the  tube.  The  proportion  of  uric  acid 
is  then  read  off  at  the  surface  of  the  fluid  as  parts  per  thousand. 

If  the  upper  meniscus  line  of  the  urine  be  between  any  of  the 
o.i  c.cm.  marks,  the  upper  number  should  be  read.  Should  the 
urine  contain  less  uric  acid  than  the  apparatus  will  in  this  manner 
indicate,  add  the  iodin  solution  to  the  mark  halfway  between  S  and 
7,  and  read  after  reaction  the  half-values.  If  the  urine  show  an 
acid  reaction,  it  can  be  used  at  once;  but  if  it  be  alkaline,  it  must  be 
made  acid  by  a  drop  of  acetic  acid.  Cloudiness  is  of  no  importance. 
If  the  urine  contain  a  considerable  sediment  of  sodium  urate,  it 
should  be  well  shaken.  Strong  colorations  of  the  urine  do  not 
affect  the  action  of  carbon  bisulphid.  Traces  of  sugar  and  albumin 
do  not  disturb  the  result,  but  if  there  be  a  very  large  percentage  of 
albumin  or  traces  of  blood  or  pus,  these  pathologic  substances 
have  to  be  coagulated  by  boiling  and  the  urine  filtered. 

The  Hopkins  modified  method  of  uric  acid  estimation  is  a 
simple  and  accurate  process  based  upon  the  fact  that  ammonium 
chlorid  precipitates  uric  acid  from  the  urine  as  ammonium  urates. 

In  a  beaker  over  gauze  warm  150  c.c.  of  urine  (made  neutral 
in  reaction)  to  40°  or  45°  C.  and  dissolve  in  it  30  gm.  of  ammo- 
nium chlorid.  After  standing  one  hour  the  precipitate  is  collected 
on  a  filter  and  washed  with  a  10  per  cent,  solution  of  ammonium 
sulphate. 

The  precipitate  is  then  washed  off  the  filter  with  100  c.c.  of 
hot  water  into  a  beaker,  15  c.c.  of  concentrated  sulphuric  acid  are 


598  CLINICAL   CHEMISTRY 

added,  and  the  whole  is  titrated  with  N/20  potassium  permanganate 
solution  (1.6  gm.  in  1000  c.c.).  The  end  of  the  operation  is 
reached  when  a  slight  permanent  red  tinge  first  appears.  One 
c.c.  of  N/2O  potassium  permanganate  solution  corresponds  to 
0.00375  gm.  of  uric  acid  in  the  150  c.c.  used. 

The  centrifuge  method  of  estimating  requires  that  the  phos- 
phates be  first  separated  by  placing  10  c.c.  of  urine  in  the  per- 
centage tube  with  about  i  gm.  of  sodium  carbonate  and  i  to  2  c.c. 
of  ammonium  hydrate.  The  phosphate  precipitate  is  thrown 
down  by  rotation,  and  the  clear  urine  poured  off  into  another 
tube.  To  this  is  added  2  c.c.  of  ammonium  hydrate  and  2  c.c.  of 
a  5  per  cent,  solution  of  silver  nitrate  (to  which  ammonium  hy- 
drate has  been  added  until  the  first  precipitate  clears  up);  and  the 
translucent  precipitate  of  silver  urate  is  separated  by  rotation. 
Having  poured  off  the  clear  liquid,  the  precipitate  of  silver  urate 
is  washed  free  of  chlorid  by  mixing  it  with  at  least  5  c.c.  of  ammo- 
nium hydrate.  The  mixture  is  then  well  rotated  until  the  precipi- 
tate is  reduced  to  its  least  bulk.  For  -nj-  c.c.  of  this  precipitate  the 
uric  acid  is  read  off  as  0.001176  gm.  in  10  c.c.  of  urine.  To  get 
percentage  this  product  is  again  multiplied  by  10.  Thus:  if  the 
reading  was  0.5,  then  5X0.00176  =  0.00588  gm.  in  10  c.c.  or  0.0588 
per  cent. 

Murexid  Reaction. — Uric  acid,  free  or  in  combination,  can  be 
identified  by  the  murexid  reaction.  To  obtain  this  the  suspected 
substance  is  treated  in  a  watch  crystal  or  porcelain  dish.  After 
adding  a  few  drops  of  strong  nitric  acid,  enough  to  dissolve,  a  slow 
heat  is  applied  to  evaporate  the  solution  to  dryness.  A  yellow  or 
reddish  residue  is  obtained.  This,  touched  with  a  drop  of  aqua 
ammonia  or  held  over  the  open  mouth  of  the  bottle  of  ammonia, 
should  turn  to  a  bright  crimson,  purple,  or  violet  (murexid)  (p.  489). 

If  the  crystals  of  uric  acid  be  examined  under  a  microscope, 
they  are  found  to  be  of  a  pointed  oval  form.  As  they  fall  they 
take  up  the  coloring-matter  of  the  urine,  which  makes  them  red  or 
brownish. 

When  the  crystals  fall  spontaneously  they  are  larger,  though 
still  minute,  and  can  be  made  out  by  the  naked  eye  as  the  only 
brown  specks  of  this  size  found  in  the  urine.  They  are  not  unlike 
grains  of  red  sand  or  ground  cayenne  pepper.  Under  the  micro- 
scope they  appear  as  small  reddish  lozenges,  sometimes  broken 
and  single,  sometimes  united  so  as  to  form  stars,  resets,  or  sheafs. 
These  are  all  modifications  of  the  simple  rhomb  or  whetstone. 
(See  Fig.  102  and  Plate  7,  Fig.  5.) 

Practical  Import. — Deposits  of  crystalline  urates  in  the  joints 
and  kidneys  are  one  expression  of  the  gouty  diathesis,  in  which 
there  is  a  tendency  for  the  nitrogenous  waste  to  take  this  shape. 
Cases  occur,  not  otherwise  related  to  gout,  in  which  the  urine 


THE   URINE  599 

deposits  free  uric  acid  spontaneously.  If  this  happens  only  in 
concentrated  urine  or  when  several  hours  have  elapsed  after 
micturition,  and  as  a  consequence  of  the  acid  fermentation,  it 
may  be  ignored  safely.  The  same  crystals,  however,  seen  in  a 
sample  soon  after  micturition  should  awaken  the  suspicion  that 
the  sediment  likewise  falls  in  the  bladder  or  in  the  kidney.  If 
persistent,  these  would  aggregate  into  calculous  masses.  About 
80  per  cent,  of  all  the  urinary  concretions  are  composed  of  uric 
acid  alone  or  mixed  with  urates.  The  solubility  of  these  in 
alkaline  fluids  is  the  basis  for  preventive  treatment  by  the  liberal 
exhibition  of  the  alkaline  bicarbonates  or  citrates. 

Purin  Bodies. — In  another  place  (p.  489)  consideration  is 
given  to  the  relationship  held  by  uric  acid  to  the  other  purin 
bodies,  the  xanthin  bases,  which  are  present  in  the  urine  in  the 
proportion  of  i  :  10  of  uric  acid.  At  the  same  place  is  discussed 
the  distinction  between  endogenous  and  exogenous  uric  acid. 
We  have  complete  control  over  the  exogenous  uric  acid  by  regu- 
lating the  diet  so  as  to  reduce  the  nucleins  and  purins  to  a  minimum 
(p.  492). 

Mixed  Urates.— Under  this  title  are  included  salts  of  uric 
acid  with  sodium,  potassium,  and  perhaps  ammonium,  magne- 
sium, and  calcium,  which  in  normal  urine  are  soluble  at  ordinary 
temperatures.  If,  however,  morning  urine  of  ordinary  acidity 
and  density  be  kept  in  a  cold  room,  its  solvent  powers  are  les- 
sened, and  it  may  become  turbid,  forming  a  surface  film  and 
throwing  down  these  mixed  urates  as  a  loose  pink  powder.  Even 
at  common  temperatures  this  sediment  may  occur  if  the  urine 
be  very  dense  and  of  higher  acidity  than  usual.  In  such  cases  the 
urates  may  not  in  themselves  be  in  excess,  but  the  urine,  owing 
to  hyperacidity,  becomes  a  poorer  solvent  for  them.  These 
conditions  are  very  frequent,  and  hence  this  deposit  is  a  very 
familiar  one;  it  is  sometimes  known  as  the  lithate  or  the  lateritious 
or  the  brick-dust  deposit.  It  is  not  at  all  difficult  to  recognize, 
being  the  only  deposit  which  clears  up  when  the  urine  is  heated. 
Again,  it  is  dissolved  when  potassium  hydroxid  is  added  to  the 
urine.  The  same  procedures  would  leave  a  phosphatic  deposit 
unchanged,  or  even  increase  the  turbidity.  In  case  of  doubt 
the  murexid  test  (see  Uric  Acid)  would  act  with  the  urates. 
(Plate  7,  Fig.  i.) 

Microscopically,  the  urates  are  found  to  be  amorphous  gran- 
ules with  a  tendency  to  form  moss-like  groups,  pinkish  in  color 
(Fig.  102).  To  distinguish  them  from  amorphous  phosphates,  a 
drop  of  potassium  hydroxid  may  be  caused  to  flow  under  the 
cover.  The  urates  will  dissolve,  but  the  phosphates  are  unaf- 
fected. (Plate  7,  Fig.  4.) 

Practical  Import. — By  referring  to  the  conditions  producing 


6oo 


CLINICAL   CHEMISTRY 


them,  it  will  be  seen  that  before   attaching  much   importance  to 
this  deposit  it  must  be  ascertained  if  the  urine  has  been  kept  in 

a  cold  place.  If  not,  then  the 
deposit  may  be  one  evidence 
of  excess  of  acid  urates  due 
to  increased  waste  of  nitrog- 
enous tissue,  such  as  occurs 
in  fever.  This  may  be  tran- 
sient, as  from  cold,  or  persist- 
ent, as  in  chronic  diseases 
causing  hectic  fever.  Some- 
times it  is  the  expression  of  a 
habit  of  defective  oxidation, 
or  it  may  be  assignable  to  a 
free  indulgence  in  meats  and 
heavy  liquors.  The  urine  can 
be  cleared  up  quite  easily  by 

FIG.  102. — Uric  acid  and  mixed  urates  (Funke).  .  .. 

making  it  alkaline,  and  some- 
times by  merely  lowering  its  acidity.  For  this  the  usual  remedy 
is  potassium  citrate  in  doses  of  J  to  i  dr.,  given  in  an  effervescent 
draught.  If  the  urates  be  persistently  deposited  while  the  urine 
is  in  the  bladder,  they  tend  to  accrete  about  a  nucleus,  and  thus 
gradually  form  a  concretion. 

Ammonium  Urate. — This  compound  of  uric  acid  has  some 
properties  differing  from  those  of  the  mixed  urates  referred  to 
above.  It  will  form  as  a  deposit  in  urine  made  ammoniacal  by 
putrescence,  and  then  appears  in  company  with  the  triple  phos- 
phate crystals.  Under  the  microscope  it  is  seen  as  dark-brownish 
spherules.  Under  this  title  some  writers  class  a  deposit  made  of 
irregular  spherules  with  spiny  projections.  These  have  been 
called  hedgehog  crystals.  Occasionally  they  look  not  unlike  an 
acarus  insect  (Fig.  97). 

Practical  Import. — The  dark  spherules  are  simply  incidental 
to  ammoniacal  fermentation.  The  spiny  globes  are  sometimes 
seen  in  the  dense,  scanty,  high-colored  urine  passed  by  children 
in  febrile  attacks.  Concretions  are  very  apt  to  be  formed  by  them 
if  the  attacks  are  of  frequent  occurrence. 

Sugar. — Sugar  in  anything  more  than  a  very  minute  amount 
is  absent  from  healthy  urine.  Some  of  the  urinary  constituents, 
such  as  uric  acid  and  creatinin,  and  the  glycuronates  of  indol  and 
skatol,  and  a  number  of  accidental  drugs,  can  be  made  to  exhibit 
reducing  powers  resembling  those  of  glucose.  In  normal  urine 
this  power  is  not  marked  enough  to  appear  distinctly  with  the 
usual  reduction  tests  when  properly  made,  whereas  in  true  gly- 
cosuria  it  is  shown  to  a  pronounced  degree.  It  is  well  to  remem- 
ber that  high-colored,  acid,  and  dense  urines  contain  a  relatively 


THE    URINE  6oi 

large  amount  of  uric  acid  and  creatinin,  and  that  with  such  sam- 
ples additional  care  should  be  observed  to  avoid  a  fallacy.  It  is 
always  advisable  before  testing  for  glucose  to  make  sure  of  the 
absence  of  albumin.1 

Glucose  as  a  Reducing  Agent. — The  most  striking  tests  make 
use  of  the  property  possessed  by  glucose  of  reducing  salts  of  copper 
and  bismuth  to  lower  oxids,  or  even  to  the  metallic  state,  when  boiled 
with  these  salts  and  an  excess  of  alkali  (Plate  8,  Figs.  1-4). 

Trommer's  test  is  made  with  J  in.  of  urine  in  the  test-tube,  to 
which  is  added  an  equal  amount  of  potassium  hydroxid  (liquor 
potassae)  and  a  few  drops  of  a  solution  of  copper  sulphate.  These 
are  heated  over  a  spirit  lamp  or  a  Bunsens'  burner  until  boiling 
begins.  A  red  or  yellow  precipitate  of  cuprous  oxid  denotes  glu- 
cose. This  is  a  crude  and  sometimes  fallacious  method  of  testing 
with  copper  sulphate.  To  obviate  its  defects  it  is  best  to  make 
the  alkaline  copper  solution  first  and  bring  it  to  the  boiling-point 
before  adding  the  urine.  But  when  the  alkali  and  the  copper  sul- 
phate are  mixed,  an  objectionable  precipitate  of  cupric  hydrate 
forms.  The  change  into  an  insoluble  hydrate  can  be  prevented 
by  adding  certain  carbon  compounds,  such  as  the  tartrates,  gly- 
cerin, mannite,  and  glucose.  Of  these,  however,  glucose  only 
has  the  power  to  abstract  oxygen  from  the  boiling  copper  solu- 
tion, throwing  down  the  red  or  yellow  cuprous  oxid  (p.  302). 

The  glycerin  cupric  test  may  be  accurately  applied  by  mixing 
in  the  tube  an  inch  of  potassium  hydroxid,  a  few  drops  of  copper 
sulphate  solution,  and  a  drop  or  two  of  glycerin.  Having  heated 
this  mixture  to  boiling,  about  10  drops  of  suspected  urine  should 
be  added.  After  waiting  a  few  seconds,  if  the  yellow  or  red  pre- 
cipitate does  not  appear,  the  mixture  must  be  brought  to  the 
boiling-point  again  and  a  few  drops  more  of  urine  added.  This 
process  must  be  repeated  until  the  yellow  or  red  precipitate 
appears  or  until  the  total  contents  of  the  tube  reach  2  in.  The 
yellow  or  red  precipitate  denotes  glucose.  In  practice  it  is  very 
convenient  to  have  the  glycerin  and  copper  ready  mixed.  This 
is  done  by  dissolving  28  gr.  of  copper  sulphate  in  a  mixture  com- 
posed of  J  fl.  oz.  of  water  and  \  fl.  oz.  of  pure  glycerin.  To  make 
the  test  fluid,  several  drops  of  this  are  added  to  an  inch  of  potas- 
sium hydroxid.  Fehling's  solution  differs  from  the  preceding  in 
using  a  tartrate  as  the  medium  for  making  a  clear  alkaline  copper 
fluid.  It  may  be  made  and  contained  in  a  single  bottle,  but  in 
that  shape  does  not  keep  well,  depositing  the  red  oxid  of  copper 
spontaneously.  It  is  better  to  have  its  components  in  two  sep- 
arate bottles  labeled  A  and  B,  of  which  equal  parts  are  to  be 

1  Artificial  saccharin  urine  for  students'  practice  can  be  made  by  adding  to 
normal  urine  a  small  quantity  of  the  ordinary  syrup  sold  by  grocers,  which  is 
mainly  glucose. 


6o2  CLINICAL    CHEMISTRY 

mixed  when  used.  To  make  solution  A,  mix  copper  sulphate 
34.64  gm.  and  water  enough  to  make  500  c.c.  For  solution  B, 
mix  Rochelle  salt  173  gm.,  solution  of  sodium  hydroxid  (specific 
gravity  1.33)  100  c.c.,  and  water  enough  to  make  500  c.c.  To 
make  Fehling's  solution  mix  equal  parts  of  A  and  B. 

Fehling's  test  is  made  by  putting  about  J  in.  of  the  above  solu- 
tion into  a  test-tube  and  diluting  it  with  2  in.  of  water.  When 
heated  to  the  boiling-point  add  a  small  amount  of  urine.  If  no 
red  or  yellow  precipitate  appears,  heat  to  boiling  again  and  add 
another  instalment  of  the  urine  short  of  an  inch  in  amount.  Heat 
to  boiling  again  and  watch  it  as  it  cools;  the  slightest  yellow  or 
red  turbidity  would  indicate  glucose. 

In  all  the  above  copper  tests  care  should  be  taken  that  the  test 
fluid  should  exceed  the  urine  in  volume,  and  that  the  contents  of 
the  tube  should  not  be  boiled,  but  merely  heated  to  the  point  of 
boiling  and  then  withdrawn  from  the  flame. 

Volumetric  Estimation. — Having  mixed  in  a  porcelain  capsule 
10  c.c.  of  Fehling's  solution  and  40  c.c.  of  water,  the  mixture 
should  be  heated  over  wire  gauze  until  boiling  begins.  While 
thus  heating  a  buret  may  be  charged  with  a  mixture  of  i  volume 
of  urine  to  9  of  water.  This  diluted  urine  should  be  allowed  to 
drop  slowly  from  the  buret  into  the  gently  boiling  test-fluid  until 
the  blue  color  of  the  copper  solution  totally  disappears.  Having 
noted  the  number  of  cubic  centimeters  required,  if  great  accuracy 
be  desired,  the  whole  process  may  be  repeated  with  fresh  materials, 
dropping  the  urine  very  slowly  as  the  reaction  approaches  its  end. 
The  solution  has  been  standardized,  so  that  10  c.c.  of  it  will  be 
decolorized  by  0.05  gm.  of  glucose.1  If  it  be  found  that  7  c.c.  of 
the  dilute  urine  were  needed,  then,  as  the  urine  was  diluted  i  part 
in  10,  we  read  it  0.7  c.c.  of  urine  =  0.05  gm.  of  glucose.  Parts 
per  hundred  can  be  calculated  by  the  ratio  0.7  :  0.05  ::  100  :  x  = 
7.14.  To  get  grains  to  the  fluidounce,  the  7.14  must  be  multiplied 
by  the  factor  4.55. 

Purdy's  Volumetric  Method. — In  practice  the  beginner  finds 
that  the  Fehling's  precipitate  of  copper  suboxid  obscures  the 
color  indications  and  errors  are  frequent  from  this  difficulty.  To 
obviate  it  the  solution  for  quantitative  purposes  is  best  made 
with  ammonia,  which  holds  the  copper  salts  in  solution.  There 
is  no  precipitate  to  cloud  the  end-point  of  the  reaction,  and  the 
change  is  sharp  from  the  blue  fluid  to  one  that  is  yellowish. 

To  make  Purdy's  solution,  take  copper  sulphate  4.75  gm.; 
glycerin  38  c.c.;  dissolve  in  200  c.c.  of  water  by  heat.  In  another 
200  c.c.  of  water  dissolve  potassium  hydroxid,  23.5  gm.,  and  mix 
with  the  copper  glycerin  solution.  When  cool,  add  strong  am- 

1  The  same  quantity,  10  c.c.,  requires  to  reduce  it,  0.067  gm.  of  lactose  and 
0.074  of  maltose. 


THE    URINE  603 

monia  water,  450  c.c.,  and  water  sufficient  to  make  1000  c.c.  It 
makes  a  sapphire-blue  solution. 

METHOD. — Put  in  a  capsule  or  beaker  35  c.c.  of  the  above 
solution  and  70  c.c.  of  water.  Put  in  the  buret  the  plain  urine. 
Boil  steadily  and  add,  drop  by  drop,  the  urine  until  the  blue 
liquid  is  colorless  and  transparent.  For  the  total  cubic  centi- 
meters of  urine  used  calculate  0.02  gm.  of  sugar.  If  the  quantity 
of  urine  used  was  4,  then 

4  c.c.  =  0.02 
i  c.c.  =  0.005 

therefore,  the  percentage  or  100  c.c.  =  0.50. 

If  less  than  4  c.c.  are  required,  dilute  the  urine  by  adding  2  parts 
of  water  and  then  multiply  the  result  by  3.  The  advantages 
found  in  students'  work  are  the  definite  end-point,  stability, 
rapidity,  and  accuracy. 

A  fallacy  results  from  the  fact  that  the  normal  reducing  power 
of  urine  from  uric  acid,  creatin,  etc.,  is  equivalent  to  about  0.5 
per  cent,  of  glucose.  Hence  some  dense,  high-colored  urines 
may  discharge  the  blue  color  after  prolonged  boiling,  even  when 
free  from  sugar.  The  whole  titration  must  be  done  quickly,  as  the 
decolorized  solution  regains  its  blue  color  on  standing  a  few  minutes. 

Bbttger's  Bismuth  Test. — As  albumin  may  interfere  with  this 
test  owing  to  the  sulphur  it  contains,  it  is  desirable  first  to  make 
sure  that  no  albumin  is  present.  If  found,  it  can  be  separated  by 
making  the  urine  slightly  acid  with  acetic  or  nitric  acid,  boiling, 
and  when  cool,  filtering.  About  i  in.  of  this  urine  (albumin-free) 
is  put  into  a  test-tube  with  i  in.  of  potassium  hydroxid  and  a  pinch 
of  bismuth  subnitrate.  The  mixture,  being  boiled  for  several  min- 
utes, will  turn  brown,  and  the  white  bismuth  salt  will  turn  gray 
or  black  if  sugar  be  present.  A  convenient  shape  is  given  to  the 
reagent  by  Nylander  in  the  following  solution,  which  contains 
both  the  alkali  and  the  bismuth  oxid:  Take  bismuth  subnitrate 
2  parts,  Rochelle  salt  4  parts,  and  caustic  soda  (solution  of  8  per 
cent.)  100  parts.  Into  a  test-tube  put  2  in.  of  urine  and  about  J 
in.  of  Nylander's  solution.  After  boiling  a  few  minutes  change 
to  a  brown  or  black  color  would  indicate  glucose.  The  result 
with  the  bismuth  test  is  not  free  from  doubt  until  the  fallacy  due 
to  sulphur  compounds  is  eliminated.  As  they  make  a  black 
precipitate  with  lead  salts,  which  are  not  affected  by  glucose, 
litharge  can  be  used  to  detect  them.  If,  when  litharge  is  substi- 
tuted for  bismuth  subnitrate  in  Bottger's  test,  a  brown  or  black 
color  be  produced,  then  sulphur  compounds  are  present,  and 
may  cause  a  black  precipitate,  making  the  test  for  glucose.  As- 
surance can  be  made  doubly  sure  by  trying  Fehling's  test,  which 
is  free  from  liability  to  this  fallacy  (Plate  8,  Figs.  3,  4). 

Picric-acid-and-potash  Test. — About  i  in.  of  suspected  urine 


604  CLINICAL    CHEMISTRY 

is  mixed  in  a  test-tube  with  J  in.  of  the  saturated  solution  of  picric 
acid  and  J  in.  of  liquor  potassium  hydroxid.  On  boiling  this 
yellow  mixture  for  one  minute  a  slight  deepening  of  color  may  occur 
in  normal  urine,  owing  to  reduction  by  uric  acid  and  kreatinin;  but 
change  to  a  dark  mahogany-red  color  would  denote  glucose. 

Phenylhydrazin  Test. — Use  an  ordinary  test-tube,  and  to  J  in. 
of  dry  powdered  phenylhydrazin  hydrochlorid  add  an  equal  volume 
of  powdered  sodium  acetate  and  an  inch  and  a  half  of  urine.  By 
gently  heating  to  the  boiling-point  the  sodium  acetate  dissolves; 
continue  boiling  for  two  minutes,  and  set  aside  for  twenty  minutes 
to  permit  the  glucosazone  to  form.  If  sugar  be  present,  the  yellow 
deposit  falls,  and  when  examined  under  the  microscope  is  seen  to  be 
chiefly  sulphur-yellow  needles  of  phenylglucosazone.  Without 
sugar  the  deposit  does  not  show  needles,  but  scales  and  brownish 
globules.  It  gives  a  similar  reaction  with  maltose,  lactose,  pentose, 
and  glycuronic  acid  (Plate  3)  (p.  481). 

Fermentation  Test. — Reducing  substances  other  than  glucose, 
such  as  are  derived  from  various  drugs  administered,  are  some- 
times present  and  render  the  observer  liable  to  a  fallacy  if  he  depend 
on  the  reduction  tests  only.  Glucose  is  the  only  substance  yet 
found  in  the  urine  which  in  one  hour  will  pass  into  the  alcoholic 
fermentation  (though  lactose  may  ferment  after  a  longer  period), 
when  brewers'  yeast  in  compressed  cakes  is  added  to  it  and  the 
mixture  allowed  to  work  in  a  warm  place.  After  twenty-four  hours 
the  glucose  will  have  disappeared,  being  resolved  partly  into  carbon 
dioxid  which  escapes  and  partly  into  alcohol  which  remains.  This 
breaking  up  of  a  dissolved  solid  into  a  lighter  and  a  volatile  part 
occasions  a  loss  of  specific  gravity  in  the  solution  proportionate  to 
the  amount  of  the  solid  involved.  Not  only  is  this  an  excellent 
test  for  the  presence  of  glucose,  but  by  the  Roberts  method  it  is 
available  for  quantitative  estimates.  This  differential-density  pro- 
cess is  simple,  requiring  an  accurate  urinometer,  some  brewers' 
yeast,  and  a  bottle  of  urine. 

The  specific  gravity  is  carefully  taken  by  a  Mohr  balance,  a 
pyknometer,  or  a  delicate  urinometer,  and  recorded;  then  about  4 
oz.  of  the  urine  are  thoroughly  mixed  with  half  a  cake  of  com- 
pressed yeast  and  set  aside  in  a  warm  place  (the  kitchen)  for 
twenty-four  hours.  Fermentation  will  prove  conclusively  that 
the  urine  is  saccharine.  When  the  fermentation  subsides,  the 
specific  gravity  is  taken  again  and  compared  with  the  first  obser- 
vation. According  to  Roberts,  each  degree  of  density  lost  stands 
for  i  gr.  of  glucose  to  the  fluidounce  of  urine.  If  percentage  be 
desired,  the  product  must  be  multiplied  by '0.219.  For  example, 
if  the  specific  gravity  before  fermentation  was  1040  and  that  taken 
afterward  was  1020,  then  1040—1020=20  gr.  of  glucose  to  the 
fluidounce  of  urine.  This  20  multiplied  by  0.219  gives  4.38  per 


THE   URINE 


FIG.  103. — Saccharometer  and  mixing 
tube. 


cent.     Sometimes  the   test  is  performed  by  collecting  the   carbon 

dioxid  gas.     To  do  this  a  test-tube  must 

be  filled   with  a   mixture   of  urine  and 

brewers'  yeast,  the  thumb  put  over  the 

mouth  so  that  the  tube  may  be  inverted, 

and  the   opening  immersed   in   a   deep 

saucer    containing    the    same    mixture. 

The  inverted  tube  having  been  securely 

fixed  must  be  kept  for  twenty-four  hours 

in  a  warm  place:     If  glucose  be  present 

to  an  amount  exceeding  o.i  per  cent., 

some  gas   will  collect  at  the  top  of  the 

tube. 

A  more  convenient  and  precise  ap- 
paratus is  Einhorn's  fermentation  sac- 
char  o  meter. 

Method:  Take  one-sixteenth  of  a  cake 
of  compressed  yeast,  shake  well  in  a 

test-tube  with  10  c.c.  of  the  urine;  pour  the  mixture  into  the  sac- 
charometer,  and  by  inclining  the  apparatus  the  mixture  easily 
flows  into  the  tube,  displacing  the  air.  Set  aside  in  a  warm  room 
for  twenty-four  hours. 

If  the  urine  contain  sugar,  the  alcoholic  fermentation  begins 
in  about  twenty  to  thirty  minutes.  The  evolved  gas  gathers  at 
the  top  of  the  tube,  forcing  the  fluid  back  into  the  bulb. 

In  twenty-four  hours  the  upper  part  of  the  graduated  tube  is 
filled  with  carbon  dioxid  gas.  The  level  of  the  fluid  in  the  tube 
indicates  by  the  numbers  the  approximate  per  cent,  of  sugar 
present.  If  the  urine  contain  more  than  i  per  cent,  of  sugar,  it 
must  be  diluted  with  water  before  being  tested.  Diabetic  urines 
of  a  specific  gravity  of  1.018-1.022  may  be  diluted  with  an  equal 
quantity  of  water  and  the  result  multiplied  by  2;  of  1.022-1.028, 
with  4  volumes  of  water,  and  the  result  multiplied  by  5. 

If  we  take,  beside  the  urine  to  be  tested,  a  normal  one,  and 
make  the  same  fermentation  test  with  it,  the  mixture  of  the  normal 
urine  with  the  yeast  will  have  on  the  following  day  only  a  small 
bubble  at  the  top  of  the  tube.  This  proves  the  efficacy  and  purity 
of  the  yeast.  If  there  be  in  the  suspected  urine  only  a  small  bubble 
at  the  top  of  the  cylinder,  then  no  sugar  is  present,  but  if  there  be 
a  much  larger  volume  of  gas,  then  there  can  be  no  doubt  that  the 
urine  contains  sugar. 

Polariscope  Test. — When  the  chemical  tests  give  a  doubtful 
report,  the  polariscope  should  be  used  (p.  61). 

Practical  Import. — The  presence  of  sugar  in  the  urine,  in 
amounts  detected  by  ordinary  tests  or  glycosuria,  as  it  is  called, 
proceeds  from  conditions  regarded  as  essentially  pathologic.  In 


606  CLINICAL    CHEMISTRY 

the  majority  of  cases  it  is  a  sign  of  diabetes  mellitus.  In  this  disease 
the  sugar  is  commonly  abundant,  averaging  4  per  cent.,  but  some- 
times reaching  the  large  amount  of  10  per  cent,  or  50  gr.  in  the 
fluidounce;  it  persists  for  many  months  and  occasions  the  excretion 
of  large  quantities  of  urine,  which  may  amount  to  2  gallons  daily, 
pale  in  color  and  of  a  mellow-apple  odor.  With  the  excess  of  water 
there  is  an  increase  in  other  natural  constituents,  such  as  urea. 
The  total  effect  of  these  solids  and  the  sugar  is  to  raise  the  specific 
gravity  above  the  normal  point.  At  the  same  time  there  is  an 
obvious  breaking  down  of  the  health;  the  patient  grows  emaciated, 
notwithstanding  his  voracious  eating  and  drinking.  The  amount 
of  sugar  excreted  and  the  cognate  symptoms  are  measurably  under 
the  control  of  a  dietetic  regimen.  By  cutting  off  saccharine  and 
amylaceous  foods  from  the  dietary,  not  only  the  proportion  of 
sugar  in  the  urine,  but  also  the  fluid  volume,  can  be  lessened. 

It  remains  to  be  said  that  glycosuria  is  sometimes  transient 
and  slight.  In  some  individuals,  usually  obese,  it  may  appear  as 
a  consequence  of  excess  in  saccharine  or  amylaceous  food.  Tem- 
porarily, glucose,  glycuronic  acid,  alkapton,  pentose,  or  some  other 
substances  giving  the  same  reduction  reactions,  though  not  fer- 
mentable, have  been  found  after  the  administration  of  ether,  chlo- 
roform, chloral,  morphin,  amyl  nitrite,  turpentine,  salicylic  acid, 
salol,  benzoic  acid,  glycerin,  camphor,  carbolic  acid,  strychnin, 
arsenic,  phosphorus,  sulphonal,  acetone,  mercuric  chlorid,  phlor- 
izin,  adrenalin,  urotropin,  and  carbon  monoxid.  Glycosuria  may 
complicate  various  diseases  of  the  brain  and  spinal  cord,  cirrhosis  of 
the  liver,  cholera,  phthisis,  pneumonia,  and  asthma.  It  may  appear 
in  the  last  month  of  pregnancy  and  disappear  soon  after  parturition. 

Pentosuria. — Traces  of  pentoses  (C5H10O5)  (p.  437)  are  some- 
times found  in  the  urine  after  ingestion  of  fruits,  wine,  and  beer, 
and  also  as  a  result  of  family  predisposition.  The  pentoses  reduce 
Fehling's  solution,  but  not  in  the  amounts  usually  found.  They 
yield  good  crystals  with  phenylhydrazin,  but  they  do  not  respond 
to  the  fermentation  test  and  are  optically  inactive.  Their  presence 
is  detected  by  Tollen's  orcin  test.  The  reagent  is  made  by  mixing 
orcein,  i  gm.;  liq.  ferri  chloridi,  25  drops,  and  500  c.c.  of  30  per  cent, 
hydrochloric  acid.  Of  this  solution  5  c.c.  are  boiled  in  a  test-tube 
and  after  removal  from  the  flame  a  few  drops  of  urine  are  added. 
If  a  fine  green  color  does  not  form,  more  urine  is  added — up  to 
i  c.c.  This  reaction  is  not  given  by  normal  or  diabetic  urine. 

Practical  Import.— No  bad  results  have  been  noted  in  the  few 
cases  studied.  From  the  mistake  in  diagnosing  pentosuria  for 
diabetes  the  patient  may  lose  the  privilege  of  life  insurance  or  be 
subjected  to  a  diabetic  regimen  which  has  no  effect  on  the  pentose. 
Pentosuria  is  usually  discovered  by  the  failure  of  dietetic  regimen 
to  influence  the  reducing  substance  in  the  urine. 


,j  ';o  ' 
1   .(uidinij 


>nrm 

i<v,  -JO!, 


lout,  av 

PT  ATF  8 
f-L  A  1  &    8. 

THE  MOST  IMPORTANT  COLOR-REACTIONS  OF  THE 
URINE. 

FIGS.  1  to  3.  Trommer's  Test  for  Sugar.— Potassium  hy- 
droxid  and  copper  sulphate. 

FIG.  1.  Urine  free  from  sugar  does  not  dissolve  copper  sulphate 
and  assumes  a  greenish-yellow  color  on  boiling. 

FIG.  2.  Urine  containing  sugar  dissolves  the  hydrated  cupric 
oxid  formed,  with  the  development  of  a  blue  color,  and  precipi- 
tates on  heating  hydrated  cuprous  oxid  in  yellowish-red  clouds 
(Fig.  3) — reduction-process. 

FIG.  4.  Bismuth-test. — Addition  of  Nylander's  solution. 
On  heating,  metallic  bismuth  is  precipitated  in  black  clouds  if 
sugar  be  present. 

FIG.  5.  Moore's  (Caramel-)  Test. — If  to  urine  containing 
sugar  is  added  one-third  the  quantity  of  potassium  hydroxid  and 
heat  applied  (for  three  minutes),  a  chestnut-brown  color  results. 

FIG.  6.  Ferric-chlorid  Reaction  in  Diabetes.— This  con- 
sists in  the  development  of  a  Bordeaux-red  color  when  diacetic 
acid  is  present  in  the  urine,  and  is  thought  to  indicate  threaten- 
ing diabetic  coma  [?]. 

FIG.  7.  Peptone-test. — When  albumoses,  etc.,  are  present  in 
the  urine  the  addition  of  potassium  hydroxid  and  solution  of 
copper  sulphate  in  the  cold  is  followed  by  the  development  of  a 
violet  color  (biuret  reaction). 

FIG.  8.  Indican-test. — If  urine  and  pure  hydrochloric  acid 
be  mixed  in  equal  parts,  and  calcium  hypochlorite  in  solution 
be  added  drop  by  drop,  any  indoxyl  present  will  be  oxidized  into 
blue  indigo  (various  intestinal  disorders,  fermentative  processes). 
The  mixture  shaken  with  ether  separates  a  blue  top  layer. 

FIG.  9.  Test  for  Biliary  Coloring-matter. — On  shaking 
with  chloroform  the  urine  from  a  case  of  jaundice  the  chloroform 
settles  and  assumes  a  yellow  color  (bilirubin). 

FIG.  10.  Heller's  Blood-test.— On  the  addition  of  one-third 
potassium  hydroxid  and  boiling,  the  precipitated  phosphates 
carry  the  blood  coloring-matter  with  them  to  the  bottom  in  the 
form  of  red  clouds. 

FIG.  11.  Test  for  Melanin. — In  cases  of  m  elan  otic  sarcoma 
the  urine  treated  with  iron  chlorid  assumes  a  deep-black  color. 

FIG.  12.  Diazo-reaction.— In  cases  of  typhoid  fever,  tuber- 
culosis, etc.,  the  addition  of  a  mixture  of  sulphanilic  acid  and 
sodium  nitrite  gives  rise  to  the  development  of  a  bright-red 
color,  apparent  also  in  the  froth  on  shaking. 

(JAKOB.) 


PLATE  8. 


THE    URINE  607 

Glycuronic    Acid.— Glucose   being    CH2OH   (CHOH)4   COH, 

when  oxidized  in  the  body,  the  alcohol  group  CH2OH  gives  up  H2 
and  takes  O  instead,  thus  changing  to  glycuronic  acid,  COOH  .- 
(CHOH)4COH.  As  this  retains  the  COH  group,  it  reduces 
Fehling's  solution.  It  is  found  in  the  animal  body  and  a  bare 
trace  in  human  urine,  combined  with  indoxyl  and  phenol.  Larger 
quantities  appear  in  the  urine  after  the  administration  of  chloral, 
camphor,  naphthol,  turpentine,  menthol,  toluol,  exalgin,  morphin, 
etc.  It  forms  compounds  which  are  closely  allied  to  the  glucosids. 
The  compounds  vary  according  to  the  drug  with  which  it  is  united — 
campho-glycuronic  acid,  menthol-glycuronic  acid,  etc.  The  free 
acid  and  the  above  glycuronates  reduce  the  oxids  of  copper  and 
bismuth  in  alkaline  solution;  hence,  they  may  be  confounded  with 
glucose.  But,  unlike  glucose,  it  does  not  ferment  with  yeast.  Its 
presence  is  suspected  when  a  sample  of  urine  reduces  Fehling's, 
Bb'ttger's,  or  Nylander's  solution,  and  it  is  levorotatory  to  polarized 
light,  and  does  not  ferment  with  yeast  (p.  436). 

Acetone  (CH3 .  CO  .  CH3),  Diacetic  Acid  (CH3.CO.CH2- 
COOH),  and  Beta=oxybutyric  Acid  (CH3 .  CHOH  .  CH2 .  - 
COOH). — These  substances  are  closely  related,  as  show^n  by  the 
formulas,  and  by  the  fact  that  diacetic  acid  is  changed  to  acetone 
by  heat.  A  trace  of  acetone  is  usually  found  in  diabetic  urine 
and  sometimes  in  healthy  urine.  When  diabetic  coma  is  impend- 
ing, there  is  a  large  increase  of  acetone  in  the  urine  and  diacetic 
acid  appears,  while  the  specific  gravity,  the  sugar,  and  the  urea 
decline.  The  diacetic  acid  is  revealed  by  adding  i  or  2  drops  of 
liquor  ferri  chloridi  to  3  c.c.  of  urine.  A  yellowish  phosphatic 
precipitate  forms,  which  should  be  separated  by  filtration.  If 
the  filtrate,  when  treated  with  a  few  more  drops  of  the  ferric  chlorid, 
does  not  yield  a  claret-wine  color,  we  may  safely  infer  the  absence 
of  the  significant  substance.  If  the  wine  color  appear  when  the 
patient  is  not  taking  salicylic  acid,  antipyrin,  kairin,  or  other  phenol 
products,  it  is  most  likely  due  to  diacetic  acid.  More  elaborate 
control-tests  can  be  applied  to  make  the  result  conclusive,  such  as 
boiling  a  fresh  sample,  which  destroys  the  diacetic  acid  and  prevents 
the  ferric  chlorid  reaction  unless  that  be  due  to  the  indifferent 
phenol  products  referred  to.  Should  the  boiled  sample  yield  no 
reaction,  another  portion  acidulated  with  dilute  sulphuric  acid  and 
extracted  with  ether  may  give  the  dark-red  color  when  the  extract 
is  treated  with  ferric  chlorid.  This  denotes  that  the  diacetic  acid 
existed  in  combination.1  (Plate  8,  Fig.  6.) 

For  minute  quantities  it  is  necessary  to  concentrate  the  acetone 
by  distilling  10  c.c.  from  100  c.c.  and  applying  the  tests  to  the 
distillate,  or  a  more  delicate  method  may  be  preferred.  Take  50  c.c. 

1  For  the  students'  practice,  ethyl  aceto-acetate,  a  few  drops,  may  be  added  to  the 
ne.     It  yields  the  same  reaction  as  diacetic  acid. 


608  CLINICAL   CHEMISTRY 

of  urine,  add  a  few  drops  of  sulphuric  acid,  and  shake  well  with 
50  c.c.  of  ether.  The  ether  extracts  the  acid  from  the  other 
urinary  constituents  and  forms  a  top  layer.  Separate  the  ether 
and  shake  the  extract  with  a  small  quantity  of  weak  solution  of 
ferric  chlorid.  Diacetic  acid  turns  it  red;  salicylic  acid  turns  it 
red  violet  (pp.  426  and  468). 

LegaPs  Test  for  Acetone. — Mix  25  c.c.  of  urine  with  25  c.c.  of 
a  strong,  freshly  made  solution  of  sodium  nitroprussid,  and  add  a 
few  drops  of  sodium  hydroxid  or  strong  ammonium  hydroxid. 
Acetone  develops  a  red  color,  and,  on  the  addition  of  acetic  acid, 
in  one  or  three  minutes  becomes  darker.  Creatinin  gives  the  red 
color,  but  it  disappears  on  adding  acetic  acid. 

There  is  no  simple  reaction  for  beta-oxybutyric  acid.  If  the 
glucose  be  removed  by  fermentation  with  yeast,  and  then  the  clear 
urine  tested  with  the  polariscope,  a  decided  rotation  to  the  left 
points  to  this  acid.  Its  specific  rotation  is  24.  Then  a  rotation  of 

i°  with  a  2  decimeter  tube  would  give        xI°°=2  per  cent.     Slight 

degrees  of  levorotation  would  mean  nothing,  as  normal  urine  is 
slightly  levorotatory. 

Practical  Import. — The  presence  of  acetone,  like  that  of  dia- 
cetic  acid,  and  beta-oxybutyric  acid  with  glucose  in  the  urine,  renders 
the  diagnosis  of  diabetes  certain.  The  gravity  of  the  disease  is  pro- 
portionate to  the  " acetone  bodies"  in  the  urine.  The  maximum 
quantity  may  be  more  than  5  gm.  in  twenty-four  hours.  Death 
from  diabetes  is  often  preceded  by  a  typic  coma  beginning  with 
indigestion,  abdominal  pain,  weakness,  and  drowsiness.  These 
symptoms  have  been  attributed  to  an  acid  intoxication  by  the  beta- 
oxybutyric  and  diacetic  acids,  which  alter  to  a  dangerous  extent 
the  normal  alkaline  salts  of  the  blood.  This  condition  has  received 
the  name  acidosis.  The  coma  attending  it  results  from  the  fact 
that  the  inorganic  alkalis,  such  as  ammonium  carbonate,  (NH4)2CO3, 
being  neutralized  by  the  acids,  can  no  longer  carry  CO2  away  from 
the  tissues  where  it  accumulates,  producing  the  phenomena  of 
asphyxia  (p.  423). 

Ammonia  in  Acidosis.— Acids  are  not  found  free  in  the  blood. 
In  acidosis  the  oxybutyric  acid  is  neutralized  by  ammonia  because 
the  fixed  alkalis  are  appropriated  to  other  uses.  Ammonia  as  a 
waste  product  (p.  495)  is  abundant  and  a  small  amount  is  normal 
in  the  urine.  Hence  toxic  acids  appear  in  urine  as  ammonium  salts. 
To  estimate  the  ammonia  is  to  learn  the  amount  of  diacetic  and 
oxybutyric  acids.  Method:  In  an  evaporating  dish  mix  25  c.c. 
of  fresh  urine  and  10  c.c.  of  milk  of  lime.  A  triangle  made  of  a  glass 
rod  is  placed  upon  this  dish  to  support  a  small  vessel  containing 

20  c.c.  of  ^  sulphuric  acid.  Cover  the  whole  with  a  bell  jar  greased 
to  fit  the  glass  plate  beneath  the  dish  and  set  aside  for  four  days. 


THE    URINE  609 

The  acid  now  holds  the  ammonia  set  free  by  the  lime.  Colored 
with  methyl  orange  as  indicator,  it  is  titrated  with  ^  NaHO.  The 
equivalent  of  the  original  20  c.c.  —  H2SO4  would  be  50  c.c.  of 

N 

—  NaHO.  Then  every  cubic  centimeter  of  NaHO  less  than  the  50 
required  to  neutralize  the  H2SO4  stands  for  0.0017  gm.  of  NH3.  It 
is  known  that  2  gm.  of  NH3  represent  6  gm.  of  organic  acid,  5  gm.  of 
NH3  =  20  gm.,  and  8  gm.  of  NH3  =  35  gm.  If  the  total  daily  out- 
put of  NH3  in  diabetic  urine  exceeds  5  gm.,  then  there  is  danger 
of  coma  from  acidosis.  Even  in  health  the  proportion  fluctuates, 
but  does  not  exceed  i  gm. 

Albumin. — Of  the  several  protein  substances  found  at  times 
in  the  urine,  the  two  of  greatest  pathologic  import  are  serum- 
albumin  and  globulin.  These  two  have  certain  differences,  but 
they  are  both  derived  from  the  blood  under  like  conditions  and 
appear  together  in  the  urine.  In  practice  it  is  not  necessary  to 
discriminate  between  them.  Other  protein  bodies,  such  as  mucin, 
nucleo-albumin,  peptone,  and  albumose,  have,  however,  each  a 
significance  entirely  different  from  that  of  albumin,  though  some 
of  their  reactions  are  similar.  When  albumin  escapes  into  the 
urine  it  remains  dissolved,  as  it  does  in  the  blood-serum,  and  can 
only  be  detected  with  certainty  by  tests  which  change  it  to  an  in- 
soluble compound  called  a  coagulum.1  This  coagulum  is  per- 
manent, and  not  a  precipitate  to  clear  up  by  the  action  of  reagents. 

Boiling  Test. — Should  the  sample  be  cloudy,  the  portion  to  be 
tested  must  first  be  freed  of  suspended  matter  by  filtration.  This 
is  easily  and  quickly  done  by  resting  the  cone  of  filter-paper  in 
the  mouth  of  a  test-tube.  In  a  few  minutes  enough  will  be  col- 
lected. When  the  turbidity  is  due  to  urates  and  apparatus  for 
nitration  is  not  at  hand,  gentle  heat  will  serve  to  clear  up  the 
urine,  and  then,  by  continuing  the  heat  to  the  boiling-point,  the 
cloud  of  coagulated  albumin  will  appear.  The  congeners  serum- 
albumin  and  globulin  are  the  only  proteins  that  coagulate  in  acid 
fluids  at  70°  C.  (160°  F.),  or  even  at  100°  C.  (212°  F.),  the  boiling- 
point,  to  which  the  heat  is  usually  carried.  The  test  is  best  made 
with  about  3  in.  of  urine  in  the  tube,  and  if  the  reaction  be  not 
acid,  it  must  be  made  so  with  one  drop  of  acetic  acid.  Holding 
the  tube  aslant,  the  flame  of  the  alcohol  lamp  or  Bunsen's  burner 
should  be  applied  to  the  upper  half  only,  while  the  tube  is  slowly 
revolved.  It  is  advisable  to  continue  heating  until  boiling  begins. 
If  albumin  be  present,  the  heated  half  grows  more  or  less  cloudy, 

1  Artificial  albuminous  urine  for  students'  practice  may  be  easily  made  by  put- 
ting the  white  of  one  egg  in  a  bottle  containing  3  fl.  oz  (or  100  c.c.)  of  a  2  per  cent, 
aqueous  solution  of  sodium  chlorid,  then  shaking  well  and  filtering.  The  filtered 
liquid  can  be  kept  indefinitely  by  adding  i  fl.  dr.  (or  4  c.c.)  of  chloroform.  To 
make  a  sample  closely  resembling  pathologic  urine,  add  10  c.c.  of  this  liquid  to 
100  c.c.  of  normal  urine. 

39 


6 10  CLINICAL    CHEMISTRY 

as  contrasted  with  the  unchanged  lower  half.  Three  points  must 
be  emphasized:  first,  if  the  urine  have  its  normal  acid  reaction,  it 
is  not  necessary  to  add  acetic  acid;  second,  even  when  it  is  neutral 
or  alkaline,  only  one  drop  of  the  acid  should  be  used,  lest  the  albu- 
min should  be  converted  into  acid-albumin,  which  is  not  coagu- 
lated by  heat;  and,  third,  phosphates  are  sometimes  precipitated 
by  boiling  off  the  dissolved  CO2  from  a  slightly  acid  specimen,  but 
this  precipitate  clears  up  on  cooling  or  on  the  addition  of  acid. 
If  the  white  clouds  appear  in  the  boiling  half,  the  test  must  be  com- 
pleted by  adding  a  jew  drops  of  nitric  acid  while  the  urine  is  hot, 
but  without  further  boiling;  the  albumin  coagulum  persists  while 
the  precipitated  phosphates  dissolve.  When  there  is  suppression 
of  urine,  the  amount  obtainable  may  be  but  a  few  drops,  which  is 
not  enough  for  a  satisfactory  result  by  boiling  the  urine.  A  dis- 
tinctive result  can  be  had  by  boiling  some  water  in  a  test-tube,  acidu- 
lating, if  necessary,  and  letting  a  drop  or  two  of  urine  fall  into  and 
mix  with  the  hot  water.  A  white  cloud  forms  if  albumin  be  present. 

This  test  is  available  for  making  an  estimate  of  the  proportion 
of  albumin.  If  the  entire  contents  of  the  tube  be  boiled  for  a  few 
minutes,  and  then  set  aside  for  twenty-four  hours,  the  flakes  of 
albumin  will  fall,  so  as  to  make  a  layer  the  volume  of  which  can  be 
stated  as  compared  with  the  total  depth  of  urine  in  the  tube;  thus, 
"the  sample  had  •£$  or  -5-  moist  albuminous  layer.' '  It  will  be  seen 
that  this  does  not  mean  that  the  urine  contains  yV  or  -J-  part  by 
weight  of  albumin. 

Nitric-acid  Test. — Heller's  Method. — If  the  urine  be  turbid,  it 
must  be  made  clear  by  pouring  it  through  a  cone  of  filter-paper 
set  in  the  mouth  of  a  test-tube.  Having  about  2  in.  of  clear 
urine,  the  tube  should  be  inclined  and  nitric  acid  allowed  to 
trickle  down  the  glass,  so  as  to  form  a  bottom  layer  of  about  J  in. 
in  depth.  If  the  acid  be  introduced  at  the  bottom  by  means  of  a 
pipet,  a  more  distinct  line  of  separation  will  be  secured.  After 
five  or  ten  minutes,  if  appearances  be  doubtful,  the  tube  should  be 
held  so  that  the  light  falls  on  it  in  such  a  way  as  to  show  up  any 
haziness  that  may  have  formed.  A  more  or  less  wide  and  distinct 
white  belt  at  the  line  of  contact  of  acid  and  urine  indicates  albumin. 
While  this  test  used  cold  is  not  quite  so  sensitive  as  that  by  boiling, 
there  are  very  few  cases  of  serious  albuminuria  that  cannot  be 
detected  by  it.  By  keeping  the  acid  and  the  urine  separate,  except 
at  the  line  of  contact,  we  ensure  that  at  some  point  there  will  be 
just  the  amount  of  acid  needed  to  coagulate  the  albumin.  A  red- 
dish zone  is  often  formed  by  the  oxidation  of  normal  urorosein. 
This  method  keeps  the  upper  part  of  the  urine  unchanged,  so  as  to 
be  a  standard  for  comparison.  There  are  cases  where  the  reaction 
is  so  questionable  as  to  make  this  standard  of  decided  value. 
Occasionally  a  dense  urine  so  treated  will  throw  out  a  cloud  of 


THE    URINE 


urates  ^  in.  nearer  the  surface,  but  not  at  the  line  of  contact, 
Sometimes  a  faint  band  of  precipitated  proteins  other  than 
albumin  appears  about  one  centimeter  above  the  line  of  contact. 
All  the  precipitates  except  albumin  clear  up  when  heat  is  applied. 
In  all  cases  it  is  best  to  use  both  heat  and  nitric  acid. 

A  quick  and  handy  method,  useful  when  the  amount  of  urine 
is  small  or  when  there  are  many  examinations  to  be  made,  as  in 
hospitals  or  dispensaries,  is  to  dip  a  pipet  of  |  in.  caliber  into  the 
urine,  taking  up  about  i  in.,  and  then  dipping  the  same  into  nitric 
acid  2  in.  deep,  relaxing  the  finger  pressure  so  as  to  admit  the 
acid.  The  finger  is  pressed  down  firmly  again,  the  pipet  lifted  from 
the  acid,  and  held  so  that  a  good  light  falls  on  the  contents.  If  no 
change  occurs,  we  may  infer  that  albumin  is  absent.  If  albumin 
be  present,  within  one  minute  a  sharp  white  ring  is  formed  at 
the  contact  line.  Albumose  and  urates  form  a  white  cloud  with 
cold  nitric  acid  when  weakened  by  dilution,  but  higher  up  the 
tube  than  the  line  of  contact  with  nitric  acid.  To  make  the 
albumin  ring  more  positive  it  is  desirable  to  apply  the  boiling  test 
in  addition  to  another  acidulated  portion  in  a  test-tube. 

Picric-acid  Test. — The  reagent  is  a  saturated  solution  made  by 
dissolving  6  gr.  of  recrystallized  picric  acid  in  i  fl.  oz.  of  hot  water, 
and  after  standing  for  a  time  decanting  the  clear  fluid.  The  urine 
must  first  be  free  from  turbidity:  if  necessary  for 
this,  it  may  be  dropped  through  a  cone  of  filter- 
paper  into  the  test-tube  until  about  3  in.  col- 
lect. The  picric  acid  is  then  permitted  to  flow 
down  the  side  of  the  tube  held  slanting  to  prevent 
the  two  fluids  mixing.  The  yellow  reagent  re- 
mains on  top,  and  if  albumin  be  present,  a  more 
or  less  cloudy  zone  will  immediately  form  in  the 
urine  as  far  as  the  picric  acid  diffuses  downward. 
If  the  upper  part  of  the  turbid  zone  be  heated  to 
the  boiling-point,  haziness  due  to  albumin  will 
increase,  and  if  the  tube  be  set  aside  will  sub- 
side as  a  compact  stratum  resting  on  the  un- 
changed column  of  urine  below. 

Beside  albumin,  the  acid  urates  and  several 
occasional  constituents,  such  as  mucin,  albumose, 
peptone,  semen,  and  the  alkaloids,  will  yield  an 
opalescence  to  picric  acid.  But  the  albumin  and 
semen  cloud  is  peculiar  in  that  it  persists  after 
heating.  This  is  a  very  delicate  test;  indeed,  it 
sometimes  reveals  albumin  in  amounts  so  small 
as  not  to  have  significance  for  the  practitioner. 
The  same  reaction  is  employed  in  estimating  the 
weight  of  albumin  by  Esbach's  albuminometer.  This  is  a  test- 


;  •* 

.11 


FIG.  104. — Esbach's 
albuminometer. 


6l2  CLINICAL    CHEMISTRY 

tube  of  strong  glass  graduated  in  the  manner  shown  in  Fig. 
104. 

The  test  solution  is  prepared  by  dissolving  10  parts  of  picric 
and  20  of  citric  acid  in  900  of  boiling  distilled  water.  After 
cooling,  a  sufficient  quantity  of  water  is  added  to  make  a  total 
of  1000  parts.  The  object  of  the  citric  acid  is  to  ensure  that  the 
liquid  shall  overcome  any  possible  alkalinity  in  the  urine.  The 
graduated  tube  is  filled  with  clear  urine  up  to  the  mark  £7,  and  then 
the  reagent  up  to  R.  It  is  then  closed  with  a  stopper,  and  the 
two  liquids  are  thoroughly  mixed  in  such  a  manner  as  to  avoid 
shaking  by  slowly  reversing  the  tube  about  ten  times.  Quick 
agitation  might  make  air-bubbles  that  cause  the  precipitate  to 
float.  These  must  be  removed  with  a  pipet.  After  standing  up- 
right for  twenty-four  hours,  a  dense  and  well-defined  coagulum 
of  albumin  falls.  The  height  of  this  sediment,  read  off  on  the 
etched  scale,  will  indicate  the  weight  of  dried  albumin  in  parts  per 
thousand  of  urine  (grams  per  liter).  While  this  process  yields 
results  which  within  a  certain  range  are  fairly  accurate  (an  error 
of  one-tenth  to  two-tenths  of  albumin),  it  is  far  more  convenient 
than  the  tedious  and  difficult,  though  more  accurate,  method  of 
separating  the  albumin  by  heat  and  acid  and,  after  filtration,  weigh- 
ing the  dried  precipitate.  Esbach's  process  will  not  give  correct 
statements  of  amounts  less  than  0.5  parts  per  1000.  When  the 
proportion  of  albumin  is  very  high — that  is,  when  the  coagulum 
stands  above  4  on  the  scale — it  is  best  to  dilute  the  urine  with  i  or  2 
volumes  of  water,  and  after  testing  multiply  the  result  by  2  or  3, 
according  to  the  degree  of  dilution. 

In  addition  to  the  time-honored  tests  already  given,  which  have 
the  confidence  of  the  profession  and  the  sanction  of  much  usage, 
there  remain  to  be  described  several  others  of  great  sensitiveness, 
but  not  sufficiently  discriminating. 

Tanret's  potassiomercuric  iodid  reagent  is  composed  of  mer- 
cury bichlorid  1.35  gr.,  potassium  iodid  3.32  gr.,  acetic  acid  20  c.c., 
distilled  water  enough  to  make  1000  c.c.  By  the  contact  method 
it  shows  a  white  belt  with  albumin,  but  also  with  other  proteins 
whose  presence  may  not  be  at  all  significant.  The  same  objec- 
tion can  be  made  to  the  solutions  of  sodium  tungstate,  of  meta- 
phosphoric  acid,  and  the  more  complex  acetic-jerrocyanid  test. 
The  last  named  is  of  extraordinary  delicacy.  It  is  applied  by 
first  making  the  urine  decidedly  acid  with  acetic  acid,  and  then 
adding  a  few  drops  of  recently  prepared  solution  of  potassium  ferro- 
cyanid.  It  precipitates  albumin,  but  also  albumose  and  peptone. 

Purdy's  Quantitative  Method  for  Albumin  (Centrifugal}. — 
The  centrifuge  estimation  by  volume  is  performed  by  putting  into 
the  percentage  tube  10  c.c.  of  urine.  To  this  is  added  2  c.c.  of  50 
per  cent,  dilution  of  acetic  acid  and  3  c.c.  of  a  freshly  made  10  per 


THE    URINE 


cent,  solution  of  potassium  ferrocyanid.  After  shaking  the  mixture 
and  standing  aside  ten  minutes  it  is  rotated  for  three  minutes  at 
1500  revolutions  per  minute.  For  every  ru-  c.c.  of  precipitate 
calculate  i  per  cent,  by  volume  of  albumin  layer.  From  this  it 
is  easy  to  find  the  percentage  of  dried  albumin  or  grains  per  fluid- 
ounce  by  consulting  the  following  table: 

Purdy's  Table  /or  Estimating  Albumin 

This  table  shows  the  relation  between  the  volumetric  and  gravimetric  percentage 
of  albumin  obtained  by  means  of  the  centrifuge  with  radius  of  6|  in.;  rate  of  speed, 
1500  revolutions  per  minute;  time,  3  minutes. 


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6 14  CLINICAL    CHEMISTRY 

A  recently  introduced  test  is  that  by  trichloracetic  acid.  It  is 
best  used  as  a  solution  (specific  gravity,  1.147)  after  the  contact 
method.  A  white  clot  forms  next  to  the  reagent  when  albumin 
or  albumose  is  present;  boiling  will  dissipate  any  cloud  not  albu- 
minous. 

For  salicylsulphonic  acid  as  a  test  see  Albumose  (p.  615). 

Practical  Import. — Except  in  certain  rare  cases,  such  as  the 
cyclic  albuminuria  of  adolescents,  albumin  is  an  indication  of  a 
serious  disturbance  in  the  function  of  the  kidney.  It  is  generally 
conceded  that  in  the  early  hours  of  the  day  a  trace  af  albumin 
can  sometimes  be  found  in  the  urine  of  young  men  otherwise  in 
apparent  health.  It  is  probable  that  even  in  these  persons  there 
is  an  alteration  in  the  kidney,  though  it  may  be  one  removable  by 
time  or  medication.  In  small  amounts  it  is  often  seen  at  certain 
stages  of  severe  specific  fevers  and  blood-poisonings,  and  just 
after  epileptic  seizures.  In  60  per  cent,  of  pregnant  women  a 
trace  of  albumin  appears  some  time  after  the  fifth  month.  This 
is  incidental  to  the  pressure  of  the  gravid  womb  on  the  renal  cir- 
culation. With  few  exceptions,  the  urine  becomes  normal  soon 
after  delivery  of  the  child.  Poisoning  by  lead,  arsenic,  and  some 
other  metals  may  occasion  it.  In  every  such  case  the  question  arises: 
Can  the  albuminuria  be  regarded  as  a  sign  of  Bright's  disease  of  the 
kidneys?  The  answer  will  be  affirmative  if  the  symptom  prove 
persistent  and  the  layer  produced  by  the  boiling  test  should  equal 
one-half  of  the  column  of  urine  in  the  tube.  For  proof  positive 
we  must  examine  the  sediment  with  the  microscope  for  tube-casts. 

The  general  condition  must  be  considered,  and  would  be  re- 
garded as  highly  confirmatory  if  characterized  by  anemia,  cardiac 
hypertrophy,  or  dropsy.  With  these  even  a  mere  trace  of  albu- 
min must  be  held  to  be  of  very  grave  import.  Reactions  of  albu- 
min with  blood  may  be  due  simply  to  the  hemorrhage,  which  may 
come  from  any  part  of  the  genito-urinary  tract.  WThen  found 
with  abundance  of  leukocytes,  it  may  be  due  to  the  fluid  of  pus, 
ami  have  no  other  significance. 

Mucin  (Nucleo-albumin}. — This  is  a  constituent  of  mucus 
which  is  coagulated  by  the  organic  acids — acetic,  citric,  picric,  and 
trichloracetic.  With  Heller's  test  it  forms  a  cloud,  not  next  to  the 
nitric  acid,  but  high  up  the  tube.  To  discriminate,  the  urine  must 
be  boiled,  when  all  clouds  disappear  except  the  one  made  by  serum 
albumin. 

Albumosuria.1 — Proteoses  or  albumoses  belong  to  the  family 
of  proteins,  sometimes  found  in  the  urine.  They  appear  in  small 
amounts  in  various  infectious  diseases,  and  are  often  referable  to 

1  Artificial  albumose  urine  for  students'  use  can  be  made  by  dissolving  in  the 
urine  some  Witte's  dry  peptone. 


THE    URINE  615 

resorption  of  disintegrated  pus.  While  soluble  in  dilute  salt 
solution,  they  are  precipitated  when  the  solution  is  saturated  with 
ammonium  sulphate.  Heat  does  not  coagulate  them. 

Tests. — To  get  significant  amounts  it  is  often  necessary  to 
evaporate  the  urine  on  a  water-bath  to  less  than  half  its  volume. 
Into  a  large  test-tube  put  2  or  3  in.  of  urine  with  an  equal  volume 
of  saturated  solution  of  common  salt,  and  about  £  in.  of  acetic  acid. 
A  precipitate  forms  if  albumose  be  present,  the  urine  clearing  up 
on  boiling  and  the  precipitate  reappearing  on  cooling.  If  it  does 
not  clear  up  on  boiling,  then  other  proteins  are  present  and  must  be 
filtered  off  while  hot.  The  return  of  the  cloud  as  the  hot  filtrate 
cools  signifies  albumose. 

If  the  hot  filtrate  be  carefully  poured  down  an  inclined  test- 
tube  so  as  to  form  a  layer  with  i  in.  of  Fehling's  solution,  a  rose- 
pink  halo  (biuret  reaction)  will  appear  at  the  line  of  contact  (PI.  8). 

Salicylsulphonic-acid  Test. — A  convenient  and  sensitive  reagent 
for  distinguishing  albumin  and  nucleoproteins  from  albumose 
is  made  by  treating  salicylic  acid  with  sulphuric  acid  and  crys- 
tallizing by  evaporation.  The  crystals  of  salicylsulphonic  acid 
may  be  safely  carried  about  in  the  pocket,  or,  better  still,  a  bottle 
of  saturated  solution  in  water  may  be  used. 

METHOD. — Two  test-tubes  are  half  filled  with  urine,  and  to  each 
is  added  i  c.c.  of  the  solution.  Shake  both  tubes  wrell.  If  a 
cloudiness  appear,  we  know  that  some  form  of  albumin  or  albumose 
is  present.  Reserving  one  tube  as  a  standard,  the  other  is  heated 
and  then  compared  with  the  standard  to  see  if  heat  have  cleared  up 
the  cloud.  If  due  to  primary  albumoses,  it  clears  under  heat,  to 
reappear  on  cooling.  If  due  to  serum-albumin  or  nucleo-albumin, 
the  cloud  persists,  unchanged  by  temperature. 

This  test  acts  in  acid  and  alkaline  urines  equally  well,  and  does 
not  precipitate  phosphates,  urates,  uric  acid,  bile,  alkaloids,  or 
drugs.  In  delicacy  as  a  test  for  albumin  it  stands  between  Heller's 
•cold  nitric-acid  and  the  boiling  tests.  Its  delicacy  may  be  counted 
as  an  objection,  for  quantities  of  albumin  too  small  to  be  of  patho- 
logic importance  may  be  shown.  The  most  serious  objection  is 
the  readiness  with  which  nucleoproteins  are  precipitated,  as  at 
present  we  have  no  means  of  readily  distinguishing  this  precipitate 
from  that  caused  by  albumin.  The  best  check  on  these  two  falla- 
cies is  obtained  by  the  use  of  Heller's  cold  nitric-acid  test  in  doubt- 
ful cases.  The  secondary  ring  higher  up  than  the  line  of  contact 
of  acid  and  urine,  given  with  nucleoproteins  by  this  test,  is  readily 
recognizable.  By  diluting  the  urine  one-half,  the  doubt  as  to  the 
significance  of  the  amount  of  albumin  is  set  at  rest.  If  the  albumin 
reaction  is  obtained  with  the  dilute  urine,  the  amount  is  of  patho- 
logic importance. 


616  CLINICAL    CHEMISTRY 

Practical  Import. — When  active  suppuration  is  going  on  any- 
where in  the  body  and  inflammatory  effusions  are  breaking  down, 
albumose  is  a  product  of  autolysis  of  the  pathologic  tissue.  It 
enters  the  systemic  circulation,  and  is  eliminated  by  the  kidney. 
It  may  thus  help  to  prove  the  existence  of  concealed  internal  suppur- 
ation. According  to  the  cause,  it  has  been  divided  into  four 
classes — pyogenic,  inorganic,  enterogenic,  and  puerperal. 

The  Bence=Jones  protein  is  a  rare  urinary  constituent  closely 
related  to  the  water-soluble  globulin  of  the  blood,  and  is  recognized 
by  the  following  tests:  At  a  temperature  of  60°  C.  (140°  F.)  it 
forms  a  gelatinous  coagulum;  at  80°  C.  (176°  F.)  it  clears,  and  at 
100°  C.  (212°  F.)  it  is  nearly  all  dissolved. 

Nitric  acid  makes  a  dense  precipitate  which  disappears  when 
warmed  and  returns  on  cooling. 

Acetic  acid,  up  to  30  per  cent.,  has  no  effect,  but  at  50  per  cent, 
a  jelly  forms  in  five  minutes  which  liquefies  on  warming.  Salicyl- 
sulphonic  acid  causes  a  copious  precipitate  which  dissolves  when 
heated,  to  reappear  on  cooling. 

Practical  Import. — This  protein  appears  in  the  urine  in 
advance  of  myeloma  and  kindred  diseases  of  the  bone  and 
marrow.  It  is  always  of  grave  significance. 

Hematuria. — Blood  imparts  to  urine  the  reaction  of  albumin 
contained  in  serum  and  a  red  or  brown  color  due  to  the  corpuscles. 
The  change  of  color  and  the  albumin  reactions  may  be  found  in 
hemoglobinuria,  a  condition  in  which  the  distinct  corpuscles  are 
not  found,  the  color  principle  being  diffused.1 

The  characteristic  feature  of  true  hematuria  is  the  red  blood- 
corpuscle.  These  biconcave  bodies  will  preserve  their  peculiar 
form  for  several  days  if  the  urine  containing  them  is  of  ordinary 
density  and  acidity.  In  a  very  dense  urine  they  lose  their  smooth 
outline  and  become  crenated.  In  a  dilute  medium  they  swell 
up  to  a  spheric  shape  and  grow  pale.  In  the  ammoniacal  urine 
which  usually  attends  cystitis  they  are  apt  to  shrivel  and  be  de- 
formed. 

Practical  Import. — Hematuria  is  a  symptom  of  hemorrhage 
from  some  part  of  the  genito-urinary  tract.  When  the  bleeding 
is  at  the  kidney,  the  blood  is  usually  well  mixed  with  the  urine, 
giving  it  a  smoky-red  appearance,  and  when  the  sediment  falls, 
bloody  renal  tube-casts  can  be  found  with  the  microscope.  It 
denotes  active  local  mischief,  or  may  be  symptomatic  of  severe 
fevers  or  neurotic  or  toxic  or  vicarious  to  menstruation  and  hem- 
orrhoids. Blood  from  the  ureter  is  apt,  before  evacuation,  to  form 

1  Artificial  bloody  urine  can  be  conveniently  prepared  from  fresh  blood  or  from 
blood  preserved  in  glycerin  or  from  scales  of  dried  blood  kept  on  hand.  When 
needed,  the  scales  are  ground  up  in  a  mortar  with  water  and  filtered.  The  filtrate 
may  be  added  to  normal  urine. 


THE    URINE  617 

clots  which  are  molded  in  that  tube  in  the  shape  of  curved  cylinders, 
looking  to  the  naked  eye  like  small  worms.  They  have  been  mis- 
taken for  parasitic  entozoa.  The  microscope  shows  them  to  be 
a  compact  mass  of  red  corpuscles.  They  may  be  due  to  local 
disease  or  injury,  or  incidental  to  the  passing  of  a  renal  calculus. 
Blood  from  the  bladder  is  usually  abundant  and  gives  to  the  urine 
a  bright  red  color,  with  shreddy  clots  visible  to  the  naked  eye.  It 
is  accompanied  by  vesical  symptoms,  such  as  pain  in  the  supra- 
pubic  region  and  perineum,  with  frequent  micturition  and  stran- 
gury. Blood  from  the  urethra  occurs  in  the  course  of  gonorrhea, 
and  reveals  its  source  by  local  symptoms  and  by  escaping  at  the 
meatus  in  the  intervals  of  micturition  (Plate  7,  Fig.  3). 

Heller's  test  for  blood-pigment  is  made  by  adding  one  third  potas- 
sium hydroxid  and  boiling  until  flocculi  of  phosphates  form.  As 
they  fall  they  carry  with  them  the  blood-pigment  and  become  brown 
or  red-yellow.  Having  collected  the  precipitate  on  a  filter,  it  dis- 
solves in  acetic  acid  with  a  red  color,  which  gradually  fades  on  ex- 
posure. It  is  an  easy  and  satisfactory  test  (Plate  8,  Fig.  10). 

Benzidin  Test. — A  much  more  sensitive  test  for  blood-pigment 
is  made  by  treating  10  c.c.  of  urine  with  i  c.c.  of  glacial  acetic  acid. 
To  this  mixture  a  third  volume  of  ether  is  added,  well  shaken  and 
set  aside.  The  supernatant  layer  of  ether  separates  more  quickly 
if  5  to  10  drops  of  alcohol  be  shaken  with  the  mixture.  With  a 
pipet  the  ether  is  transferred  to  another  test-tube  containing  the 
benzidin  reagent,  which  has  previously  been  made  by  mixing  0.5  c.c. 
of  a  freshly  prepared  solution  of  a  little  benzidin  in  2  c.c.  of  glacial 
acetic  acid  with  2  or  3  c.c.  of  hydrogen  dioxid. 

If  blood  is  present,  the  reagent  turns  green  or  blue  in  two  minutes; 
after  five  minutes  it  changes  to  a  dirty  purple.  The  test  is  both 
accurate  and  reliable  to  the  extent  of  a  negative  result,  excluding 
the  possibility  of  blood.  As  there  are  a  number  of  substances 
which  give  the  same  reaction,  if  a  positive  response  be  obtained, 
this  must  be  confirmed  by  the  guaiac  and  the  hemin  tests  (p.  529). 

Hemoglobinuria. — In  certain  dissolved  states  oj  the  blood  the 
coloring-matter  is  set  free  from  the  disintegrated  corpuscles  and 
eliminated  by  the  kidneys.  It  imparts  to  the  urine  a  dark-brown 
color.  The  albumin  reaction  is  obtained  by  all  the  tests  for  that 
substance.  However,  the  coagulum  formed  is  not  white,  but  red 
or  brownish.  To  distinguish  this  condition  from  hematuria  the 
microscope  is  necessary. 

In  hematuria  we  not  only  have  the  color  and  the  albumin  re- 
action, but  also  the  red  corpuscles.  The  latter  are  not  found  in 
hemoglobinuria.  With  the  spectroscope  the  dark  bands  of  reduced 
blood-pigment  can  be  identified  by  the  special  means  employed 
with  that  instrument  (Plate  4,  Fig.  i,  f-h).  Almen's  test  by 


6l8  CLINICAL    CHEMISTRY 

overlaying  with  urine  a  mixture  of  tincture  of  guaiac  and  a  solution 
of  hydrogen  peroxid  (or  old  ozonized  oil  of  turpentine)  gives  a 
characteristic  blue  color  (pp.  538  and  563). 

Practical  Import. — Hemoglobinuria  occurs  in  various  blood 
diseases,  microbic  and  otherwise,  such  as  typhus,  purpura,  and 
pyemia.  Sometimes  it  is  the  result  of  the  toxic  action  of  hydrogen 
arsenid,  phosphorus,  carbolic  acid,  chloral,  or  potassium  chlorate. 
Certain  individuals  suffer  from  a  periodic  form,  often  attributable 
to  cold  or  malaria,  and  sometimes  of  doubtful  origin. 

Bile. — In  conditions  causing  jaundice  we  can  always  find  bile- 
pigment  in  the  urine,  but  the  biliary  acids  are  seldom  present  in 
amounts  great  enough  to  give  the  lake-colored  reaction  with  the 
well-known  Pettenkofer's  test  by  cane-sugar  and  sulphuric  acid 
(Plate  8,  Fig.  9). 

Oliver's  test  for  biliary  acids,  peptone  solution,  is  very  sen- 
sitive, but  gives  results  so  uncertain  as  not  to  merit  detailed 
description  in  a  practical  study  of  the  urine  as  brief  as  this  is 
required  to  be.  On  the  other  hand,  the  bile-pigment  can  be 
detected  in  the  urine  of  icterus  even  earlier  than  it  will  show 
itself  on  the  conjunctiva.  When  notably  present,  it  gives  tints 
varying  from  bright  sulphur  yellow  to  olive  green. 

Gmelin's  test  for  biliary  pigment  is  very  sensitive  and  easily 
performed.  A  few  drops  of  the  suspected  urine  are  poured  in  a 
white  plate,  and  near  them  a  small  amount  of  yellow  nitric  acid 
(containing  lower  oxids  of  nitrogen).  Having  caused  the  two 
fluids  to  touch  edges,  bile-pigments  will  change  at  the  line  of  contact 
into  modified  pigments.  There  will  be  a  play  of  colors  in  regular 
order — green,  blue,  violet,  red,  and  yellow.  Green  and  red  domi- 
nate, and  will  persist  after  the  others  fade.  The  same  test  can  be 
applied  in  a  tube  by  overlaying  the  nitric  acid  with  the  biliary 
urine. 

Practical  Import.— A  trace  of  bile  found  will  help  to  diagnose 
hepatic  troubles  when  the  icterode  hue  elsewhere  is  doubtful. 

Pyuria. — It  has  been  stated  above  that  sometimes  the  albu- 
minuria  may  be  due  to  pus,  the  fluid  of  which  is  albuminous.  The 
distinctive  elements  of  pus  are  the  numerous  leukocytes.  These, 
under  the  microscope,  can  be  recognized  by  their  resemblance  to 
the  white  blood-cells.  They  are  spheric,  granular,  and  opaque, 
but  on  the  addition  of  acetic  acid  lose  their  opacity  and  show  at 
the  center  one,  two,  or  three  nuclei.  One  cannot  be  sure  from 
the  form  whether  the  leukocyte  is  derived  from  mucus  or  from  pus. 
With  the  former  comparatively  few  are  to  be  found,  with  the  latter 
a  great  number.  Mucus  can  be  further  distinguished  from  the 
pus  from  the  fact  that  the  proteid  mucin  will  not  become  hazy  with 
heat  and  nitric  acid,  while  the  albumin  of  liquor  puris  coagulates 


THE    URINE  619 

like  serum-albumin.  Again,  if  the  suspected  sediment  be  separated 
by  decanting  the  upper  part  of  the  urine,  and  then  into  the  deposit 
a  piece  of  caustic  potash  is  stirred,  if  the  deposit  be  pus,  it  becomes 
tough  and  gelatinous;  if  mucus,  thin  and  flaky  (Plate  7,  Fig.  2). 

Practical  Import. — If  pyuria,  the  albumin  reaction  raises  the 
question  as  to  whether  in  addition  to  pus  there  is  serum-albumin 
of  renal  origin.  We  are  helped  to  a  conclusion  by  the  fact  that 
the  albumin  in  pyuria  is  usually  scanty,  and  a  large  amount  would 
therefore  be  considered  as  over  and  above  that  due  to  pus.  If  tube- 
casts  are  found  with  the  microscope,  then  renal  mischief  can  be 
assumed.  A  sudden  irruption  of  pus  would  most  likely  be  due  to 
the  evacuation  of  an  abscess  into  the  genito-urinary  passages. 
Persistent  pyuria  points  to  chronic  catarrhal  inflammation,  the  site 
of  which  can  be  determined  by  local  symptoms. 

Chyluria. — Chyle  is  rarely  found  in  the  urine.  At  first  sight 
of  a  sample  containing  it  one  would  suppose  that  milk  had  been 
added  to  it.  It  may  happen  that  the  amount  of  chyle  present  is 
so  large  that  the  fat  particles  rise  like  the  cream  on  milk,  and  the 
fibrin  of  the  chyle  may  form  a  spontaneous  clot,  resembling  blanc- 
mange. As  the  chyle  contains  serum-albumin,  it  would  respond 
to  the  tests  for  that  substance.  To  make  out  the  fatty  character 
of  the  suspended  part,  a  portion  of  the  urine  should  be  agitated 
with  ether  and  potassium  hydroxid,  which  dissolves  the  envelopes 
and  melts  the  fat  particles  together  as  a  surface  layer,  leaving  the 
urine  clear  beneath.  The  microscopic  character  is  much  like 
that  of  milk — that  is,  it  contains  myriads  of  small,  bright,  round 
particles  which  dissolve  in  ether.  To  eliminate  the  chance  of 
deception  from  milk,  the  patient  can  be  required  to  urinate  in  the 
presence  of  a  witness. 

Practical  Import.— This  symptom  generally  appears  in  those 
who  have  lived  in  the  tropics,  where  it  is  not  very  uncommon. 
It  denotes  a  lymphatic  connection  with  the  urinary  passages,  and 
not  infrequently  is  associated  pathologically  with  the  presence  of 
Filaria  sanguinis  hominis. 

Epithelium.— Ordinarily  the  urine  is  clear,  but  even  in  health 
it  occasionally  shows  a  faint  cloud  called  the  nubecula,  which  the 
microscope  reveals  to  be  made  of  epithelial  de*bris.  In  some 
persons  a  small  amount  of  the  waste  material  of  cells  from  the 
mucous  lining  of  the  bladder  and  other  parts  of  the  urinary  tract 
may  occur,  and  have  no  significance.  A  lar^e  amount  with  mucus, 
or  still  more  with  pus,  would  indicate  catarrh  of  some  portion  of 
the  urinary  tract.  Practically,  the  main  point  to  be  determined  is 
as  to  whether  the  cells  are  from  the  kidney  or  not. 

Renal  epithelium  is  spheric,  granular,  and  nucleated,  with  an 
indistinct  cell  wall.  The  coexistence  of  casts  of  the  uriniferous 


620 


CLINICAL    CHEMISTRY 


tubules  would   corroborate   their    testimony  as    to    the    existence 
of  renal  desquamation.     Cells  from  extrarenal  parts  are  distinct, 


FIG.  105. — Epithelium  from  the  urine:  a,  b,  Epithelium  from  the  bladder,  from  the  pelvis  of  the 
kidney;  c,  caudate  epithelium  (pelvis  of  the  kidney?);  d,  renal  epithelium  partly  changed  into  fat 
(Vierordt).  Greatly  magnified. 

nucleated,  and  flattened,  being  oval,  spindle-shaped,  cylindric,  or 
tessellated,  according  to  site.  Cylindric  or  caudate  cells  may  be 
derived  from  the  pelvis  of 
the  kidney,  from  the  prostate 
gland,  from  Cowper's  gland, 
from  the  urethra,  or  from 
some  parts  of  the  bladder. 
Bladder  epithelium  is  usually 
flat  and  irregularly  oval; 
sometimes  desquamation  oc- 
curs in  patches  of  cells  joined 
at  their  edges.  In  the  urine 


FIG.  106. — Hyaline  casts  (narrow  and  toler- 
ably broad  ones).     Greatly  magnified. 


FIG.  107. — a  and  c,  Waxy  casts  (Jaksch);  b,  a  cast 
containing  crystals  of  oxalate  of  lime.  Greatly  mag- 
nified. 


of  women  large  translucent  flat  cells  from  the  vagina  are  nearly 
always  present. 

Tube=casts.— As  a  result  of  structural  mischief  in  the  kidney, 
there   are  formed  in   the    tubules   cylindric    casts    of    coagulable 


THE    URINE 


621 


material,  which  is  sometimes  fibrin,  sometimes  mucoid  matter,  and 
sometimes  the  plastic  substance  resulting  from  the  disintegration 
of  the  cellular  lining.  Individually  they  are  too  small  to  be  seen 
by  the  naked  eye,  but  in  the  amount  usually  collected  they  appear 
as  a  light-gray  sediment,  or  perhaps  as  a  cloud  at  or  near  the 
bottom  of  the  glass  vessel.  Under  the  microscope  they  are  seen 
to  be  minute  cylinders,  sometimes  glassy,  sometimes  opaque  and 
granular,  and  sometimes  displaying  cells.  They  can  be  classified 
accordingly  as  epithelial,  hyaline,  granular,  fatty,  and  those  made 
of  blood-disks.  If  in  doubt  as  to  the  nature  of  the  material  com- 
posing the  casts,  staining  may  be  restored  to.  The  best  results 
are  obtained  by  fixing  the  sediment  to  the  slide  with  gentle  heat 
and  staining  the  casts  with  solution  of  Sudan  III.  (which  detects 


FIG.  108. — Red  blood-corpuscles,  partly  as  rings,       FIG.  109.— Epithelial   casts   (Jaksch). 
and    casts     of     red     blood-corpuscles     (Eichhorst).  Greatly  magnified. 

Greatly  magnified. 

fatty  change)  and  iodin,  which  distinguishes  the  amyloid  or 
waxy  cast. 

Epithelial  casts  have  opaque  spheric  renal  cells  imbedded  in 
some  plastic  matrix.  By  the  number  of  these  one  can  judge  of 
the  activity  of  the  desquamative  process  in  cases  of  nephritis. 
They  are  usually  found  in  acute  nephritis  (see  Fig.  109). 

Hyaline  casts  are  always  transparent,  and  sometimes  require 
skilful  arrangement  of  light  to  show  them  at  all.  In  case  of  doubt 
they  may  be  stained  with  methylene-blue.  They  can  be  grouped 
in  two  subvarieties,  in  one  of  which,  the  mucous,  would  be  placed 
those  that  are  soft  and  of  delicate  outline;  in  the  other,  the  waxy, 
those  that  are  well  defined  and  brittle. 

The  mucous  casts  alone  are  sometimes  found  without  any 
other  sign  of  nephritis,  and  hence  must  be  regarded  as  not  always 


622 


CLINICAL    CHEMISTRY 


FIG.  i  io.— Granular  casts  ( Jaksch). 
Greatly  magnified. 


of  serious   import.     The  waxy  casts,  on  the  contrary,    are    never 

found  but  when  the  kidneys  are  diseased  (see  Figs.  106  and  107). 

Granular  casts  (Fig.  no),  as  the  name  indicates,  are  composed 

of  or  contain  opaque  granules  which  have  a  yellowish  hue.     The 

material  may  be  mucoid  or  waxy,  or  such 
material  as  is  produced  by  cellular  debris. 
Fatty  casts  are  such  as  have  fat  par- 
ticles in  the  matrix,  with  or  without  the 
other  bodies  mentioned  above.  If  numer- 
ous, they  are  regarded  as  evidence  of  fatty 
change  in  the  kidney. 

Blood  casts  (Fig.  108)  are  reddish  and 
opaque;  they  are  literally  minute  clots  of 
blood  which  have  taken  shape  from  the 
tubules  into  which  the  effusion  occurs. 
The  corpuscles  may  be  so  packed  as  to 
be  pressed  out  of  their  biconcave  shape  and  appear  as  reddish 
circles. 

Practical  Import. — It  has  been  stated  under  previous  sections 
that  if  albuminuria  or  hematuria  or  an  epithelial  deposit  be  of 
renal  origin,  careful  search  of  several  portions  of  the  deposit  with 
the  microscope  will  most  likely  find  tube-casts.  It  occasionally 
happens  in  cases  of  Bright's  disease  that  the  albuminuria  will  dis- 
appear, and  still  the  casts  can  be  found  in  the  urine.  Hence  much 
importance  is  attached  to  them  in  renal  diagnosis.  As  regards 
the  significance  of  particular  varieties,  it  must  be  noted  that  if  the 
mucous  cast  alone  be  present,  it  does  not  prove  nephritis,  but  any 
of  the  other  varieties  would  do  so. 

It  often  happens  that  several  varieties  occur  in  the  same  sam- 
ple: this  probably  denotes  that  the  lesion  is  at  different  stages  in 
different  parts  of  the  organ. 

Cystin. — This  substance  contains  sulphur,  the  composition 
being  expressed  by  the  formula  C6H12N2S2O4.  One  product  of  its 
decomposition  is  the  gas  hydrogen  sulphid;  hence  a  test  for  it  is 
to  boil  the  suspected  material  with  a  solution  of  lead  oxid  in  sodium 
hydroxid.  If  cystin  be  present,  it  will  form  a  black  precipitate  of 
lead  sulphid.  As  it  is  very  sparingly  soluble  in  water,  any  con- 
siderable amount  in  the  urine  would  not  remain  in  solution,  but 
be  deposited.  The  deposit  is  usually  abundant,  light,  and  to  the 
naked  eye  resembles  amorphous  urates.  Unlike  urates,  it  is  not 
dissolved  by  heat,  though  it  is  soluble  in  ammonia  and  also  in  the 
vegetable  acids.  When  a  drop  of  the  ammonia  solution  is  exposed 
uncovered  on  a  glass  slide,  it  deposits  crystals  which  the  microscope 
shows  to  have  the  form  of  hexagonal  tablets  (Fig.  84). 

The  extensive  use  of  iodoform  for  surgical  dressings  has  been 


THE    URINE 

the  source  of  a  fallacy.  The  crystals  of  iodoform,  accidentally 
mixed  with  the  urine  and  viewed  by  the  microscope,  will  present 
hexagonal  tablets  not  unlike  those  of  cystin.  The  chemical  re- 
action is  wholly  different,  and  the  pronounced  odor  of  iodoform 
should  at  once  excite  suspicion. 

Practical  Import. — Cystin  exists  in  the  protein  molecule  as 
a  preformed  group  which  is  liberated  in  the  tissues  and  destined 
to  be  further  decomposed.  Certain  rare  individuals  and  families, 
from  causes  not  ascertained,  have  the  anomaly  of  metabolism 
which  results  in  a  failure  to  break  down  the  cystin  and  leads  to  its 
appearance  in  the  urine.  When  present  there,  it  is  usually  in  con- 
siderable quantities.  Patients  do  not  apparently  suffer  in  health, 
but  the  deposited  cystin  eventually  forms  a  concretion  in  the 
bladder. 

Leucin  and  Tyrosin. — These  two  substances  are  considered 
together,  because  they  are  by-products  of  the  same  processes  of 


FIG.  in. — Leucin  and  tyrosin  (Laache). 

digestion,  and  when  from  disease  certain  biliary  matters  appear 
in  the  urine,  these  can  be  found  also.  Tyrosin  is  recognized  by 
its  turning  red  when  boiled  with  Millon's  reagent  of  mercuric 
nitrate;  when  another  portion  is  carefully  warmed  with  sulphuric 
acid  and  then  treated  with  a  drop  of  ferric  chlorid,  it  yields  a 
violet  color.  In  the  urine  tyrosin  may  be  in  solution  or  it  may 
be  thrown  down  spontaneously  as  a  greenish-yellow  deposit.  The 
microscope  will  resolve  this  deposit  into  bundles  of  yellow  acicular 
needles  in  radiating  stars,  crosses,  or  sheaves  (p.  525). 

Leucin,  being  more  soluble,  is  less  apt  to  form  a  spontaneous 
deposit,  but  if  a  few  drops  of  the  suspected  urine  are  allowed  to 


624  CLINICAL    CHEMISTRY 

evaporate  by  exposure  on  a  glass  slide,  both  leucin  and  tyrosin 
will  appear  in  the  residuum.  Under  the  microscope  leucin  is 
recognized  as  greenish-yellow  globes  with  concentric  markings  or 
radiating  spines.  If  the  deposit  be  touched  with  a  drop  of  nitric 
acid,  cautiously  evaporated  to  dryness,  and  then  moistened  with 
sodium  hydroxid,  the  leucin  residue  will  turn  yellow  or  brown 
(p.  499)^ 

Practical  Import. — These  two  bodies  are  found  with  icterus  in 
certain  maladies  when  the  liver  is  seriously  involved,  as  in  acute 
yellow  atrophy  of  the  liver,  phosphorus-poisoning,  typhoid,  and 
yellow  fever. 

Spermatozoa. — These  bodies,  if  present  in  considerable  number 
in  the  urine,  form  a  whitish  cloud.  When  taken  up  with  the  pipet, 
the  sperm  detaches  as  a  thready,  drop-like,  viscid  mucus.  When 
only  a  few  are  present,  they  impart  no  marked  naked-eye  property, 
and  in  looking  for  them  with  the  microscope,  unless  a  proper 
oblique  light  be  used,  they  may  escape  observation.  In  the  urine 
they  lose  at  once  their  vibratile  motion,  and  yet  for  days  retain 
their  structural  characters,  the  small,  transparent  oval  body  or 
head  with  the  very  attenuated  cilium,  the  whole  being  only  -g-J-g-  in. 

long- 
Practical  Import. — Before  drawing  conclusions  as  to  their 
significance,  it  must  be  ascertained  if  the  sample  containing  them 
be  not  the  first  micturition  after  coitus.  If  not,  they  may  be  the 
washing  out  of  the  remains  of  a  nocturnal  emission  of  semen. 
Their  only  important  relation  is  as  an  indication  of  spermator- 
rhea — i.  e.,  the  escape  of  sperm  independent  of  the  sexual  act 
occurring  during  the  waking  hours. 

Pneumaturia. — It  is  a  very  rare  symptom  for  the  last  portion 
of  urine  to  be  accompanied  by  the  passage  of  air  from  the  urethra. 
This  is  sometimes  associated  with  tympany  of  the  bladder  and 
may  be  the  result  of  accidental  introduction  of  air  during  irriga- 
tion of  the  bladder  or  as  the  result  of  knee-breast  position  for  ex- 
amination of  the  bladder.  Another  group  of  cases  is  due  to  an 
organism,  like  the  Bacterium  lactis  aerogenes,  which  develops  an 
odorless  gas,  usually  hydrogen.  A  third  group  includes  those  in 
which  there  is  a  fistulous  opening,  admitting  gas  from  the  rectum 
and  from  abscesses. 

Microorganisms. — As  it  is  a  fluid  containing  more  or  less 
organic  matter  in  solution,  the  urine  is  a  fertile  medium  for  the 
development  of  microscopic  vegetation.  The  spores  or  germs 
of  these  minute  plants  come  from  the  containing  vessels  or  from 
the  dust  that  floats  in  the  air. 

The  common  molds,  such  as  penicillium,  appear  in  a  few  days 
on  a  stale  urine.  They  are  seen  microscopically  as  minute  jointed 


THE    URINE  625 

threads  matted  together  in  a  mycelium.  Saccharine  urine  fur- 
nishes the  soil  for  the  growth  of  the  yeast  fungus,  Saccharomyces 
cerevisia,  the  spores  of  which  may  be  derived  from  the  floating 
dust  of  the  air.  It  may  be  of  value  as  corroborating  other  evi- 
dence of  the  presence  of  sugar.  The  latter  plant  is  recognized 
as  oval  cells  with  granular  contents  and  nuclei  multiplying  mainly 
by  buds,  but  sometimes  by  spore-bearing  stems.  Even  before 
discharge  the  sarcinae  of  the  bladder  will  reproduce  in  the  urine, 
and  be  the  cause  of  obscure  vesical  symptoms.  Their  microscopic 
structure  is  peculiar  from  the  cubic  form  of  the  little  masses  made 
by  the  reproduction  of  the  more  minute  round  particles.  The 
bacteria  of  putrefaction,  the  Micrococcus  urea,  vibriones,  and  other 
similar  organisms  will  flourish  not  only  in  the  urine  outside,  but 
even  before  micturition.  They  are  identified  as  extremely  minute 
rods  or  granules,  single  or  threaded,  still  or  vibratory. 

Staining. — With  a  pipet  a  small  drop  of  the  sediment  is  trans- 
ferred to  the  slide  and  spread  in  a  thin  film.  To  fix  the  cells  and 
organisms  the  film  may  be  set  aside  to  dry  spontaneously  or  be 
heated  over  a  flame  cautiously  for  three  minutes,  keeping  the  heat 
of  the  slide  below  a  point  painful  to  the  skin  of  the  hand.  When 
dry,  it  is  bathed  in  a  few  drops  of  solution  of  carbol  fuchsin,  which 
stains  bacteria  and  tissue-cells.  Heat  is  again  applied  and  the 
film  again  stained  by  applying  for  three  minutes  Gabbet's  blue 
solution,  which  makes  most  pathogenic  organisms  blue,  but  leaves 
the  tubercle  bacilli  red. 

When  the  gonococcus  is  sought,  the  first  stain  to  be  used  must 
be  eosin  and  the  second  methylene-blue. 

Practical  Import  of  the  Bacteria. — A  highly  important  signifi- 
cance of  bacteria  in  the  urine  depends  upon  the  fact  of  their  causing 
decomposition  of  the  urea  while  still  in  the  bladder.  If  the  ammo- 
niacal  products  be  detained  in  the  bladder,  they  are  very  apt  to 
cause  cystitis.  It  is  of  the  greatest  importance  to  guard  against 
the  introduction  of  their  germs  by  means  of  unsterilized  instru- 
ments, such  as  catheters  and  sounds.  It  is  possible  for  them  to 
get  access  to  the  urine  in  the  bladder  from  the  purulent  discharges 
of  a  deep-seated  gonorrhea  or  gleet.  In  paralysis  of  the  bladder 
they  appear  to  have  the  power  of  spontaneous  entrance.  In  that 
event  the  harm  they  may  do  must  be  obviated,  as  far  as  possible, 
by  frequent  and  thorough  evacuations  of  the  bladder  and  washings 
with  antiseptic  fluids. 

When  the  specific  pathogenic  bacteria  are  looked  for,  it  must 
be  with  high-power  immersion  lenses  and  substage  condensers 
after  drying  and  staining  the  residue  by  the  approved  methods  of 
bacteriology. 

It  must  be  noted  that  the  urine  in  passing  through  the  urethra, 
4o 


626 


CLINICAL   CHEMISTRY 


of  healthy  subjects  may  wash  out  micro-organisms  that  colonize 
there.  Among  these  is  mentioned  a  diplococcus  resembling  the 
gonococcus  of  gonorrhea  in  all  respects  save  that  it  is  not  found 
in  pus-corpuscles,  a  large  streptococcus,  and  even  a  bacillus  which 
neither  by  form  nor  by  staining  can  be  distinguished  from  the 
tubercle  bacillus.  The  doubtful  bacillus  is  usually  seen  singly, 
whereas  the  bacilli  coming  from  ulcerating  urogenital  tuberculosis 
are  generally  in  groups  or  crowds  considerable  in  number,  like 
those  of  a  pure  culture  (Fig.  112).  Inoculation  experiments  would 
serve  to  distinguish  them  from  the  non-tubercular  bacilli.  The 
coexistence  of  hectic  fever  and  wasting  with  pyuria  and  masses  of 
these  bacilli  in  the  sediment  would  prove  highly  confirmatory  of 
their  tubercular  origin. 


v 

*  *      rr 
•v   » 

.fV 

FIG.  112. — Pure  culture  of  tubercle  bacilli  in  the  urine  in  tuberculosis  of  the  genito-urinary  appar- 
atus (Zeiss's  homogeneous  immersion  fa,  eye-piece  No.  4;  drawn  with  a  camera  lucida;  magnified 
about  noo)  (Vierordt). 

When  the  pathogenic  bacteria  are  made  out  in  the  sediment 
unmistakably  by  form  and  number,  they  point  to  the  specific  associ- 
ated disease — the  tubercle  bacilli  to  miliary  tuberculosis,  the 
erysipelas  cocci  to  erysipelatous  nephritis,  the  pus  micrococci  to 
pyemia  or  endocarditis,  the  gonococcus  to  gonorrhea. 

The  booklets  of  echinococcus  may  be  found  in  the  urine,  denot- 
ing the  presence  of  hydatid  cysts  somewhere  in  or  about  the  urinary 
apparatus.  Other  parasites  occasionally  seen  in  the  urine  of 
persons  who  have  lived  in  the  tropics  are  Distoma  hamatobium, 
Strongylus  gigas,  and  Filaria  sanguinis. 

Ehrlich's  Typhoid  Diazo-reaction.1 — In  95  per  cent,  of  the 

1  Artificial  diazo-urine  for  students'  practice  may  be  made  by  adding  to  10  c.c. 
of  urine  i  c.c.  of  a  solution  of  alpha-naphthylamin  (o.i  gm.  in  10  c.c.  of  water  and 
5  c.c.  of  hydrochloric  acid). 


THE    URINE  627 

cases  of  typhoid  fever  an  unknown  chromogen  appears  in  the 
urine,  which  develops  a  red  color  under  the  conditions  of  the  follow- 
ing test:  Two  solutions  are  made  up  and  kept  in  separate  bottles; 
one  contains  i  gm.  of  sulphanilic  acid  dissolved  in  water  95  c.c., 
with  hydrochloric  acid,  5  c.c.  The  other  is  0.5  gm.  of  sodium 
nitrite  in  100  c.c.  of  water.  The  test  is  made  by  mixing  J  c.c.  of 
the  sodium  nitrite  with  50  c.c.  of  the  sulphanilic-acid  solution,  and 
to  a  suitable  amount  adding  an  equal  volume  of  the  urine.  The 
two  are  shaken  together  and  ammonium  hydrate  is  cautiously 
poured  in  to  overlay  the  mixture.  At  the  line  of  contact  normal 
urine  will  appear  more  or  less  orange,  while  pathologic  urine  gives 
a  garnet  red.  The  red  color  will  color  the  foam  when  the  mixture 
is  shaken,  and  if  the  test-tube  be  emptied  into  a  basin  of  water, 
a  salmon  color  is  produced  (Plate  8,  Fig.  12). 

Practical  Import. — This  reaction  is  commonly  present  in  typhoid 
fever,  .is  rarely  absent  in  septicemia,  and  has  been  frequently  ob- 
served in  tuberculosis. 

FALLACY. — A  similar  reaction  occurs  from  the  presence  of  sali- 
cylic acid,  phenacetin,  antipyrin,  and  other  aromatic  compounds, 
as  the  result  of  their  administration. 

They  must  be  excluded  from  the  regimen  of  the  patient  before 
the  test  can  be  regarded  as  significant. 

Urinary  Concretions. — In  four-fifths  of  the  cases  urinary  con- 
cretions are  composed  of  uric  acid  and  urates.  Calcium  oxalate, 
or  mulberry  calculi,  stand  next  in  the  frequency.  The  rarer  primary 
varieties  are  blood  concretions,  cystin,  xanthin,  calcium  phosphate, 
calcium  carbonate.  Secondary  to  any  of  these  there  occurs  at 
the  last  stage  in  the  history  of  a  calculus  a  deposit  of  mixed  phos- 
phates. These  form  a  white  crust,  precipitated  upon  the  calculus 
as  a  result  of  ammoniacal  decomposition  in  the  urine  changing  the 
reaction  and  making  the  phosphates  insoluble. 

A  concretion  should  be  sawed  through  the  middle,  so  as  to  expose 
its  concentric  layers.  A  small  portion  of  each  distinct  layer  may 
be  examined  by  the  following  procedures: 

Calcine  a  portion  of  the  powder  on  platinum  foil  in  a  Bunsen 
burner  or  blowpipe  flame: 

A.  It  chars  and  leaves  but  little  ash  =  (uric  acid,  urates,  cystin, 
xanthin,  blood). 

It  gives  murexid  reaction  =  (uric  acid  or  urates). 
It  dissolves  in  boiling  water  =  (urates). 
It  does  not  dissolve  in  boiling  water  =  (uric  acid). 
Cystin  and  xanthin  are  very  rare;  the  first  can  be  recognized 
by  its  test  given  in  another  place. 

B.  It   chars   very   slightly   and   leaves   very   much   ash  =  (phos- 
phates, oxalate,  or  carbonate  of  calcium). 


628  CLINICAL   CHEMISTRY 

1.  Test  a  fresh  portion  with  dilute  hydrochloric  acid.     It  is 
soluble  with  effervescence  =  (carbonates  are  present).     It  is  sol- 
uble without  effervescence  =  (phosphates  or  calcium  oxalate). 

2.  Test  a  fresh  portion  with  acetic  acid.     It  is  soluble  without 
effervescence  =  (phosphatic);  it    fuses    into    a    bead    on    platinum 
foil  =  (mixed  phosphates);  it  does  not  fuse  =  (calcium  phosphate);, 
it  is  insoluble  =  (calcium  oxalate,  which,  when  calcined  on  plati- 
num, leaves  an  ash  that  turns  red  litmus  blue,  or  effervesces  with 
HC1). 


INDEX 


ABSORPTION,  96 
Acetaldehyd,  409 
Acetamid,  495 
Acetamidophenol,  469 
Acetanilid,  478 
Acetic  acid,  417,  553 

aldehyd,  409 

ether,  433 

Acetone,  413,  426,  607 
Acetonuria,  413,  607 
Acetphenetidin,  479 
Acetyl,  417 
Acetylene,  383,  447 

series,  382 
Achlorhydria,  547 
Achroodextrin,  441,  543 
Acid,  acetic,  409,  417,  418,  444,  553 

acetylsalicylic,  469 

amido-acetic,  499 

amino -acetic,  499 

aminocaproic,  499 

aminoglutaric,  499 

aminopropionic,  499 

aminovaleric,  499 

antimonious,  292 

arsenic,  286 

arsenous,  266 

aspartic,  525 

benzoic,  465 

beta-oxybutyric,  422,  607 

boric,  208 

bromic,  144 

butyric,  417,  420,  444,  553 

cacodylic,  287 

capric,  417 

caproic,  417 

caprylic,  417 

carbamic,  235 

carbolic,  454 

carbonic,  103,  191 

chloracetic,  420 

chloric,  140 

chlorous,  140 

cholalic,  538 

cholic,  558 

chromic,  351 

citric,  425 

cresylic,  460 

cyanic,  199 

dextrolactic,  422 


Acid,  diacetic,  426,  607 
diaminocaproic,  499 
diaminovaleric,  499 
dithionic,  168 
ethyl-sulphuric,  430 
formic,  417 
gallic,  470 
glacial  acetic,  409 
phosphoric,  189 
gluconic,  436 
glutamic,  421,  525 
glutaric,  421 
glycocholic,  558 
gly colic,  421 
glycuronic,  436,  607 
hippuric,  465,  499,  579 
homogentisic,  582 
hydriodic,  147 
hydrobromic,  144 
hydrochloric,  122,  135,  546,  550 
hydrocyanic,  194 
hydroferricyanic,  345 
hydroferrocyanic,  344 
hydrofluoric,  148 
hydrosulphurous,  168 
hypobromous,  144 
hypochlorous,  140 
hyponitric,  177 
hyponitrous,  175 
hypophosphorous,  191 
hyposulphurous,  168 
iodic,  147 
isosuccinic,  421 
kinic,  508 

lactic,  422,  444,  546,  552 
manganic,  348 
margaric,  420 
meconic,  512 
melissic,  409 
metaphosphoric,  189 
molybdic,  187,  189,  362 
muriatic,  135 
myronic,  443,  539 
nicotinic,  505 
nitric,  169 

nitro-hydrochloric,  173 
nitro-muriatic,  173 
nitrous,  175 
nucleic,  532 
oleic,  421 

629 


630 


INDEX 


Acid,  orthophosphoric,  190 

oxalic,  200,  421 

oxyacetic,  498 

oxy butyric,  422 

palmitic,  417,  420,  426 

paralactic,  422 

pentathionic,  168 

perbromic,  144 

perchloric,  140 

periodic,  148 

permanganic,  348 

persulphuric,  168 

phenol-sulphonic,  458 

phospho-molybdic,  362 

phosphoric,  189 

.phosphorous,  190 

phthalic,  466 

picric,  458 

propionic,  417 

proteins,  551 

prussic,  194 

pyrogallic,  462 

pyrophosphoric,  190 

pyrosulphuric,  168 

pyrotartaric,  421 

quinic,  508 

quinotannic,  508 

racemic,  423 

saccharic,  436 

salicylic,  467 

salicyl-sulphonic,  470 

sarco-lactic,  422 

silicic,  206 

sozolic,  458 

stannic,  298 

stearic,  417,  420,  427 

succinic,  421 
,    sulphanilic,  567 

sulphobenzoic,  482 

sulphocarbolic,  458 

sulphocyanic,  199,  345 

sulphonic,  415,  430 

sulphovinic,  430 

sulphuric,  160 

sulphurous,  158 

sulphydric,  156 

tannic,  470 

tartaric,  423 

taurocholic,  558 

tetrathionic,  168 

thiocyanic,  200,  345 

thiosulphuric,  168 

trichloracetic,  420 

trithionic,  168 

uric,  488,  579 

uroleucic,  582 

valeric,  417,  420 

xantho-proteic,  458 
Acidimetry,  124,  550,  584 
Acidosis,  423,  608 

ammonia  in,  608 
Acids,  123,  129,  137,  372 

amido-,  494,  498,  525,  535 


Acids,  amino-,  494,  498,  525,  535 

aromatic,  454,  485 

biliary,  558 

definitions  of,  123 

detection  of,  123 

dibasic,  162 

fatty,  417 

free  mineral,  139,  551 

hydroxy-,  454,  485 

ketone-,  426 

monobasic,  162 

nomenclature  of,  140 

organic,  372,  421,  552 

oxy-,  139,  144,  147,  168 

strength  of,  133 

sulphonic,  430 

thio-,  414 
Acid-salts,  162 

Acidum  hydriodicum  dilutum,  147 
Aconitin,  521 
Acrolein,  402 
Actinic  waves,  58 
Adamkiewicz's  reaction,  500,  526 
Adenase,  539 
Adenin,  490,  491,  539 
Adeps  lanas,  558 
Adrenalin,  461 
^Ether,  403 

universal,  17,  58 
Affinity,  chemical,  62,  70 
Agaric,  517,  519 
Agglutinins,  522 
Aggregates,  93 
Air,  composition  of,  105 

liquid,  108 
Alabaster,  241 
Alanin,  499,  525 
Albumen,  524,  527 
Albumin,  524,  527 

digestion  of,  554 

in  urine,  609 

nucleo-,  532 

serum-,  524,  609 
Albuminates,  530 
Albuminoids,  524 
Albuminous  substances,  524 

analytical  reactions  of,  526 
Albumins,  527 
Albumoses,  533 
Albumosuria,  556 
Alcohol,  392,  395 

absolute,  395 

amyl,  399 

benzyl,  453,  463 

butyl,  399 

denatured,  393,  395 

diluted,  395 

ethyl,  395 

methyl,  392 

tests  for,  392 
Alcoholic  liquors,  397 
Alcohols,  371,  392,  399 

aromatic,  453,  463 


INDEX 


63 1 


Alcohols,  constitution  of,  392,  394 
diatomic,  399 
dihydric,  399 
monatomic,  399 
primary,  400 
secondary,  400 
tertiary,  400 
triatomic,  399 
trihydric,  399 
Aldehyd,  acetic,  406 
ammonia,  407 
benz-,  464 
par-,  410 
Aldehyds,  406 
Aldol,  410 
Aldoses,  434 
Ale,  397 

Aliphatic  compounds,  371,  372 
Alizarin,  474,  551 

sodium  sulphonate,  474,  551 
Alkali  metals,  211,  236 
Alkalimetry,  127 
Alkaline  earths,  236 
Alkalis,  125,  211 
Alkaloids,  501,  521 
antidotes  to,  503 
cadaveric,  517,  521 
classification,  503 
detection  of,  503,  522 
extraction  of,  502 
separation  from  tissue,  521 
Alkaptonuria,  582 
Alkylanilin,  476 
Alkyl  radicals,  417 
Allantoin,  494 
Allotropic  modifications,  76 
Alloxan,  489,  490 
Alloxuric  bases,  489 
Alloy,  definition  of,  210 
Allylene,  382 
Almen's  test,  617 
Alum,  254 
Alumina,  253 
Aluminium,  251 

analytical  reactions  of,  255 
and  ammonium  sulphate,  254 
and  potassium  sulphate,  254 
bronze,  252 
chlorid,  253 
hydroxid,  252 
naphthol-disulphonate,  473 
oxid,  253 
sulphate,  253 
Alumnol,  473 
Amalgam,  210,  306 
ammonium,  231 
tin-,  298 
Amanitin,  519 
Amaranth,  red,  477 
Amido-acetic  acid,  498 
-acids.     See  Amino-acids. 
benzene,  476 


Amido-compounds,  476 
-diacids,  525 
-phenol,  478,  479 
-phenyl,  476 
Amidogen,  494 
Amids,  372,  494 
Amin,  diphenyl-,  471 
ethyl-,  497 
methyl-,  497 
propyl-,  497 
Amino-acetic  acid,  499 
Amino-acids,  494,  498,  525,  535 
Amino-compounds,  476 
Amins,  372,  494,  497 
Ammonia,  231,  525,  608 
derivatives,  494 
liniment,  233 
substituted,  494 
water,  232 

toxicology  of,  233 

fatal  dose  and  period,  233 
postmortem  appearances,  234 
symptoms,  233 
tests  for,  235 
treatment,  233 
Ammoniated  mercury,  313 
Ammonio-copper  compounds,  302 
-magnesium  phosphate,  189,  578,  586 
-nitrate  of  silver,  275 
Ammonium,  231 
acetate,  234 
amalgam,  231 
benzoate,  465 
bicarbonate,  235 
carbamate,  235,  492,  535 
carbonate,  233,  234,  495,  535,  578,  585 
chlorid,  234 
cyanate,  200 
derivatives,  494 
formate,  195 
hydroxid,  232 
lactate,  495,  535 
molybdate,  189,  362 
nitrate,  234 
phosphate,  235 

-magnesium  phosphate,  189,  578,  586 
-sodium  phosphate,  235 
sulphid,  235 
sulphydrate,  235 
urate,  600 
valerate,  417 
Amorphism,  152 
Amorphous  phosphorus,  178 
Ampere,  49 

Amphoteric  reaction,  498 
Amygdalin,  194,  443,  464,  539 
Amyl  alcohol,  399 

nitrite,  431 
Amylamin,  517 
Amylases,  537,  543,  556,  567 
Amylene,  381 
hydrate,  381 


632 


INDEX 


Amylodextrin,  441 
Amyloid  degeneration,  531 

substance,  531 

Amylolytic  enzyms,  537,  556 
Amylopsin,  556 
Amylum,  440 

iodatum,  146 
Anacidity,  549 
Analysis,  definition  of,  63,  134 

gas,  84 

gravimetric,  126 

organic,  363 

proximate,  363 

ultimate,  363 

urinary,  522 

volumetric,  126 
Anilid,  478 
Anilin,  476 

dyes,  477 
Animal  charcoal,  99 

food,  542 
Anions,  128 
Anisidin,  480 
Anode,  46 

Anthracene,  445,  474 
Anthracite  coal,  98 
Anthraquinon,  474 
Antibodies,  523,  563 
Antidotes  to  acids,  138,  165,  171,  203 

alkalis,  215 

alkaloids,  503 

antimony,  294 

arsenic,  270 

barium,  246 

carbolic  acid,  456 

copper,  304 

cyanids,  196 

hydrocyanic  acid,  196 

lead,  324 

mercury,  315 

nitric  acid,  171 

oxalic  acid,  203 

phosphorus,  181 

silv:--.  336 

sulphuric  acid,  165 

zinc,  356 
Antifebrin,  478 
Antimonious  chlorid,  292 

oxid,  292 
Antimony,  291 

antidotes  to,  294 

black,  291 

butter,  292 

chlorid,  292 

crude,  291 

oxid,  292 

potassium  tartrate,  292 

sulphid,  291,  294 

sulphurated,  291 

terhydrid,  292 

toxicology,  292 

chronic  poisoning  from,  293 


Antimony,  toxicology,  detection  of,  296 
fatal  dose  of,  293 
period  of,  293 

postmortem  appearances,  294 
quantitative  estimation  of,  297 
symptoms  of,  293 
tests  for,  294 
treatment  of,  294 
trichlorid,  292 
trioxid,  292 
Antipyrin,  481 

toxicology  of,  482 
Antiseptics,  458,  460 
Antitoxins,  522 
Anuria,  580 
Apomorphin,  513 

Apothecaries'  weights  and  measures,  iy 
Aqua,  85 

acidi  carbonici,  103 
ammonia,  233 
destillata,  85 
fords,  169 

hydrogenii  dioxidi,  88 
regia,  173 
Aqueous  vapor,  40,  85 

tension  of,  40 
Arabinose,  437 
Arecolin,  503 
Argentum,  333 
Arginin,  525,  527 
Argol,  423 
Argon,  98 
Aristol,  453  ^ 
Aromatic  acids,  464 
alcohols,  462 
amido-compounds,  476 
compounds,  476 
series,  445 
Arsenic,  263 
acid,  286 
antidotes  to,  269 

detection  of,  in  case  of  poisoning,  282 
eating,  273 
oxids,  266,  286 
sulphids,  290 
terhydrid,  265 
toxicology,  266 

cadaveric  imbibition  of,  291 
chronic  poisoning  from,  270 
detection  of,  in  gastric  contents  and 

viscera,  282 

distribution  of,  in  system,  285 
fatal  dose  of,  269 

period  of,  269 
in  air,  288 
in  anilin  dyes,  288 
in  beer,  288 
in  cleaners,  28" 
in  household  articles,  288 
in  king's  yellow,  290 
in  medicinal  preparations,  267,  280 
in  orpiment,  290 


INDEX 


633 


Arsenic  in  Paris  green,  290 

in  preservatives,  287 

in  realgar,  290 

in  Scheele's  green,  290 

in  soil,  291 

in  urine,  289 

in  wall-paper,  284 

medical  uses  of,  264,  272 

normal,  285 

pentoxid,  286 

physiologic  effects  of,  265 

postmortem  appearances  after,  270 

quantitative  determination  of,  284 

symptoms  of  poisoning  from,  268 

tests  for,  in  complex  solutions,  276 
in  simple  solutions,  275 
in  solid  form,  273 

treatment  in  poisoning  by,  269 

trichlorid,  265 

trioxid,  266 

trisulphid,  273 

white,  266 
Arsenic-eating,  273 
Arseniuretted  hydrogen,  265 
Arsenous  acid,  266 

anhydrid,  266 

iodid,  287 

oxid,  266 

Arsen-phenol-amin,  287 
Arsin,  265 
Asbestos,  242 
Aseptol,  458 
Ash,  bone,  241 
Aspartic  acid,  498,  525,  535 
Aspirin,  469 
Astral  oil,  379 
Atmospheric  air,  105 

pressure,  106 

Atom,  definition  of,  109,  in 
Atomic  theory,  109 

weights,  determination  of,  no 
Atomicity,  114 
Atoms,  76,  109,  250 

quantivalence  of,  114,  251 
Atoxyl,  287 
Atropin,  503,  506 

and  ptomains,  517 

aromatic  test  for,  507 

in    morphin    and    opium    poisoning, 

5U 

postmortem  appearances  after,  507 

separation  from  tissue,  517 

symptoms  of  poisoning  by,  507 

tests  for,  507 

treatment  of  poisoning  from,  507 
Auric  chlorid,  359 

sulphid,  359 
Aurum,  358 
Autolytic  enzyms,  539 
Avogadro's  law,  77,  95 
Azins,  481 
Azoturia,  581 
Azurite,  300 


BACTERIA,  pathogenic,  500,  517 
death  point  of,  567 
in  milk,  567 
in  stomach,  546 
in  urine,  565 

Bacteriolytic  enzyme,  539 
Baking  powders,  227,  255 
Balance,  18 
Balsams,  452 
Barite,  245 
Barium,  245 

antidotes  to,  246 

carbonate,  246 

chlorid,  246 

chromate,  247 

dioxid,  66 

hydroxid,  245 

nitrate,  246 

oxid,  236,  245 

sulphate,  246 

tests  for,  247 
Barley  sugar,  438 
Barometer,  107 
Baryta,  236,  245 
Bases,  definition  of,  124,  129 
Basham's  mixture,  346 
Battery,  galvanic,  48 
Beckmann's  apparatus  for  cryoscopy,  38 

for  determining  boiling  point,  369 
Beer,  397 
Beet-sugar,  438 
Belladonin,  506 
Bell-metal,  301 
Bence-Jones'  protein,  616 
Benzaldehyd,  464 
Benzene,  445,  446 

hydroxids,  453 

nucleus,  448 

series,  445,  446 

test,  617 
Benzidin,  483 
Benzin,  379 
Benzoic  acid,  465,  569 
Benzoin,  465 
Benzol,  446 
Benzo-pyrrole,  486 
Benzo-sulphinidum,  482 
Benzoyl  chlorid,  466 

sulphonic  imid,  482 
Benzyl  alcohol,  463 

amin,  476 

Benzyl-glycocol,  465,  499 
Beryllium,  117 
Betain,  517 
Betelnut,  503 
Betol,  473 

Bettendorff's  test,  275 
Bicarbonate  of  potassium,  220 

sodium,  228 

Bichlorid  of  mercury,  309 
Bichromate  of  potassium,  351 
Bile,  558 

detection  of,  in  urine,  618 


634 


INDEX 


Biliary  acids,  558,  618 

calculi,  559 

pigments,  559,  618 
Bilirubin,  559 
Biliverdin,  559 
Biologic  test,  563 
Bismuth,  330 

carbonate,  330 

citrate,  331 

hydroxid,  330 

nitrate,  331 

oxid,  330 

oxy-salts,  330 

subcarbonate,  330 

subnitrate,  331 
arsenic  in,  287 

sulphid,  332 
Bismuthyl,  330 

carbonate,  330 

nitrate,  331 

Bisulphid  of  carbon,  193 
Biuret  reaction,  496,  526,  554 
Black  antimony,  291 

-lead,  98 

oxid  of  copper,  302 
of  manganese,  348 
mercury,  308 

-wash,  308 

Bleaching-powder,  140 
Blood,  561 

coloring-matter,  529 

corpuscles,  561 

detection  of,  564 

in  urine,  616 

fibrin,  562 

phagocytes,  562 

plasma,  562 

platelets,  562 

-serum,  562 

-stains,  examinations  of,  564 
Blow-pipe,  114 
Blue  mass,  307 

pill,  307 

Prussian,  345 

-stone,  303 

TurnbulPs,  345 

vitriol,  303 
Boas'  test,  549 
Boiling  point,  41,  369 

test,  551 
Bone,  241 

-ash,  241 

-black,  99 

-oil,  483 
Borax,  209 

bead,  208 

detection  of,  209,  568 
Boric  acid,  208 

test  for,  209,  568 
toxicology  of,  209,  568 
Boron,  208 

trioxid,  208 


Bbttger's  bismuth  test,  546 

Botulism,  520 

Boyle's  law,  107 

Brandy,  397 

Brass,  301 

Bread,  alum  in,  255 

soda,  228 
Brimstone,  150 
Brittleness,  29 
Bromates,  144 
Brombenzenes,  449 
Bromic  acid,  144 
Bromid-gelatin  process,  335 
Bromids,  analytical  reactions  of,  144 
Bromin,  142 

detection  of,  143 

fatal  dose,  143 

symptoms  of  poisoning  from,  143 

treatment  of  poisoning  from,  143 

water,  142 
Bromism,  144 
Bromoform,  391 
Bronze,  301 
Brucin,  511 

separation  from  tissues,  etc.,  521 

symptoms  of  poisoning  by,  512 

tests  for,  512 

toxicology,  512 
Bunsen  burner,  114 
Burets,  124 

Burnett's  disinfectant,  355 
Butane,  375,  376 
Butene,  381 
Butter,  420,  428,  565 

of  antimony,  292 
Butterine,  428 
Buttermilk,  565 
Butylamin,  517 
Butylene,  381 

Butyric  acid,  420,  428,  553 
Butyrin,  420,  428 

CACODYL,  287 
Cacodylate  of  sodium,  287 
Cacodylic  acid,  287 
Cadaveric  alkaloids,  517 
Cadaverin,  500,  517 
Cadmium,  117 

sulphid,  276 
Caesium,  117 
Caffein,  490,  491 
Calcined  magnesia,  243 
Calcium,  237 

analytical  reactions  of,  242 

carbid,  239,  383 

carbonate,  240 

chlorid,  238 

fluorid,  148 

hydroxid,  237 

hypochlorite,  239 

oxalate,  203,  591 


INDEX 


635 


Calcium  oxid,  237 
phosphate,  241 
sulphate,  241 
sulphid,  239 
superphosphate,  241 
Calc-spar,  58 
Calculi,  biliary,  558 

urinary,  536 
Calomel,  309 
Calorie,  34,  73,  541 
Calorimeter,  34,  541 
Calx,  237 

chlorinata,  140 
sulphurata,  239 
Camphor,  453 
Cane-sugar,  437 
Caramel,  438 
Carbamid,  494 
Carbanion,  192 
Carbazotic  acid,  452 
Carbinols,  463 
Carbo  animalis,  99 
purificatus,  99 
ligni,  99 
Carbohydrates,  372,  433 

in  the  body,  443 
Carbolic  acid,  445,  454 
antidotes  to,  456 
symptoms  of  poisoning  by,  455 
tests  for,  457 
toxicology,  455 
Carboloferric  test,  457,  552 
Carbon,  98 
bisulphid,  193 
circulation  of,  104 
compounds,  371 
dioxid,  102 
in  blood,  562 
toxicology,  1 06 
symptoms  of,  106 
tests  for,  1 06 
treatment  in,  106 
disulphid,  193 
monoxid,  100 

hemoglobin,  spectrum  of,  101,  531 
in  smokeless  fuel,  101 
postmortem  appearances  after,  101 
simple  tests  for,  101 
symptoms  in  poisoning  by,  101 
tests  for,  101 
toxicology,  101 

treatment  in  poisoning  by,  101 
tetrachlorid,  389 

Carbonates,  analytical  reactions  of,  103 
Carbonic  acid,  103 
diamid,  193 
oxid,  101 

Carbonyl,  192,  385 
chlorid,  192,  386,  388 
diamid,  193 
Carborundum,  207 
Carboxyl,  385,  417 


Carbylamin,  498 
Carnalite,  212,  215,  241 
Casein,  528,  565,  566 
Caseinogen,  528,  565 
Caseose,  533 
Cast-iron,  337 
Casts,  urinary,  620 
Catalases,  538,  563 
Catalyser,  retarding,  195 
Catalysis,  87,  536 
Cathode,  46 

rays,  53 
Cations,  128 
Caustic,  335 

lunar,  335 

potash,  213 

soda,  224 
Celestite,  245 
Cell,  dry,  47 

galvanic,  47 

Grenet,  47 

Leclanche,  47 
Celluloid,  443 
Cellulose,  442 

nitro-,  443 

Centigrade  thermometer,  31 
Centrifuge,  577 

tests  for  milk,  574 

for  urine,  577 
Cerium,  361 

oxalate,  361 
Cesium,  231 
Cevadin,  515 
Chains,  371,  448 

closed,  448 

open,  371 
Chalk,  237,  238 
Chalybeate  waters,  85,  256 
Charcoal,  99 

animal,  99 
Charles'  law,  107 
Cheese,  528,  565 
Chemical  action,  definition  of,  62 

affinity,  62,  69 

divisibility,  109 

energy,  69 

equations,  70 

formulas,  112 

philosophy,  108 

reactions,  112 

symbol,  definition  of,  112 
Chemistry,  analytical,  134 

definition  of,  62 

inorganic,  62 

organic,  62,  363 
Chili  saltpetre,  225 
Chinolin,  488 
Chloracetic  acids,  420 
Chloral,  410 

amid,  497 

formamid,  497 

hydrate,  411 


INDEX 


•Chloral,  toxicology,  411 

cases  of  poisoning  by,  411 
estimation  of,  412 
fatal  dose  of,  412 
isolation  of,  412 
physiologic  action,  411 
postmortem  appearances  after,  411 
symptoms  in  poisoning  by,  411 
tests  for,  412 

treatment  in  poisoning  by,  411 
Chloranion,  131,  140 
Chlorates,  analytical  reactions  of,  141 
Chloric  acid,  140 

oxids,  139 

Chlorid  of  lime,  119,  140 
Chloridion,  131 

Chlorids,  analytical  reactions  of,  131 
Chlorin,  118 

acids,  140 

and  hydrogen,  121 

family,  149 

oxids,  139 

toxicology  of,  121 

water,  120 

Chlorinated  lime,  119,  140 
Chlorodyn,  512 
Chloroform,  384 

as  solvent  of  alkaloids,'  521 

cases  of  poisoning  by,  387 

fatal  dose  of,  387 
period  of,  387 

isolation  of,  389 

physiologic  action  of,  387 

postmortem  appearances  after,  387 

properties  of,  386 

symptoms  in  poisoning  by,  387 

tests  for,  388 

treatment  in  poisoning  by,  387 
Chlorous  acid,  140 

oxid,  139 

tetroxid,  139 
Chocolate,  490 
Choke-damp,  102 
Cholalic  acid,  558 
Cholesterin,  558,  559,  560 
Choletelin,  559 
Cholin,  517,  518 
Chondrogen,  528,  531 
Chondroitin,  531 
Chondro-mucoid,  531 
Chondroproteins,  531 
Chromates,  analytical  reactions  of,  352 
Chrome  alum,  254 

yellow,  325 
Chromic  acid,  351 

hydroxid,  350 

oxid,  350 
Chromium,  350 

green,  350 

ions  of,  350 

sulphate,  352 

toxicology,  352 


Chromium,  toxicology,  fatal  dose  of,  352 

period  of,  352 
postmortem       appearances       after 

poisoning  from,  352 
tests  for,  352 
treatment  in  poisoning  from,  352 

trioxid,  351 

Chromoproteins,  527,  529 
Chyluria,  560 
Chyme,  ^545 
Chymosin,  545 
Cider,  397 

Cinchona  alkaloids,  503,  508 
Cinchonidin,  508 
Cinchonin,  508 

sulphate,  509 
Cinnabar,  306 
Citric  acid,  425 
Claret,  397 
Classification,  116 
Clay,  251 

Clinical  thermometer,  32 
Clotting  enzyms,  538,  545 
Coagulases,  538,  545 
Coagulated  proteins,  526,  533 
Coagulation,  526,  533,  562 
Coal,  99,  445 

-tar,  445 

dyes  that  are  harmless,  477 
Cobalt,  357 
Cocain,  503,  507 

symptoms  of  poisoning  from,  508 

tests  for,  508 

toxicology,  508 
Codamine,  512 
Codein,  512 
Coffee,  490 
Cognac,  397 
Cohesion,  28,  62 
Coin  silver,  301 
Coke,  98 
Colchicin,  521 
Collagen,  528 
Collidin,  485,  518 
Collodion,  443 
Colloidal  copper,  300 

platinum,  93,  536 

silver,  333 

solutions,  93 
Colloids,  93,  524 
Colonial  spirits,  392 
Colostrum,  564 
Columbian  spirits,  392 
Columbium,  117 
Combustion,  72 
Common  salt,  225 
Complement,  523 
Compound  ethers,  417,  430 

radicals,  194,  377 
Compounds,  decomposition  of,  363 

definition  of,  63,  in 
Concentrated  lye,  224 


INDEX 


637 


Concentration  of  solution,  90 
Congo-red  test,  483,  548 
Coniin,  503,  504 

and  ptomains,  517 

separation  of,  from  tissue,  517 

symptoms  in  poisoning  from,  504 

tests  for,  504 

toxicology,  504 

treatment  in  poisoning  by,  504 
Conjugate  proteins,  527,  529 
Cooking  soda,  224 
Copper,  300 

acetate,  303 

ammonio-sulphate,  305 

antidotes  to,  304 

arsenite,  303 

black  oxid,  302 

chlorids,  302 

colloidal,  for  water  purification,  301 

hydroxid,  302 

ions  of,  301 

oxid,  302 

pyrites,  300 

subacetate,  303 

sulphate,  303 

sulphid,  305 

tests  for,  305 

toxicology,  303 

acute  poisoning  from,  symptoms  of, 

,3°3.         .       . 
chronic  poisoning  from,  304 

distribution  of,  in  nature,  300 
separation  of,  from  animal  matter, 

366 

Copperas,  342 
Corindin,  518 
Corpse  light,  373 
Corrosive  alkalies,  211 

chlorid  of  mercury,  309 

sublimate,  309 
Corundum,  253 
Cotton,  442 
Coulomb,  49 
Cream,  570,  572 

of  tartar,  222 
Creamometer,  570,  572 
Creatin,  493,  535 
Creatinin,  494,  535 
Creolin,  460 
Creosol,  460 
Creosote,  460 
Cresol,  460 
Cresylic  acid,  460 
Creta  praeparata,  240 
Critical  temperature  and  pressure,  44 
Crookes  tube,  54 
Cryolite,  252 
Cryoscopic  method,  368 
Cryoscopy  of  blood,  38 

of  urine,  39 
Crystallization,  152 
Crystallography,  152 
Crystalloids,  93 


Cumene,  446,  452 
Cumol,  446,  452 
Cuprammonium,  302 
Cupric  acetate,  302 

arsenite,  303 

chlorid,  302 

ferrocyanid,  304 

hydroxid,  302 

oxid,  302 

sulphate,  303 

sulphid,  304 
Cuprite,  300 
Cuprous  oxid,  302 
Cuprum,  301 
Curd,  566 
Current  electricity,  45 

strength,  49 
Cyanates,  199 
Cyanhydric  acid,  194 
Cyanic  acid,  199 
Cyanidion,  199 
Cyanids,  analytical  reactions  of,  199, 

antidotes  to,  199 
Cyanogen,  194 
Cyanuric  acid,  492 
Cyclic  compounds,  372,  445 
Cymene,  452 
Cy stein,  501 
Cystin,  500,  525,  622 
Cytosin,  490 


D ALTON'S  atomic  theory,  109 

laws,  1 08 
Daturin,  506 
Davy's  safety-lamp,  103 
Decay,  370,  479 

Decomposition  by  electricity,  50,  78,  128 
heat,  363 
light,  335 
Deliquescence,  84 
Deodorizers,  140 
Desiccator,  162 
Desmoid  test,  555 
Developers,  335 
Dewees'  carminative,  244 
Dew-point,  86 
Dextrin,  395,  441 
Dextrorotation,  58 
Dextrose,  434 
Diabetic  urine,  444 
Diacetic  acid,  426 

ether,  443 
Dialysis,  92 
Dialyzed  iron,  341 
Dialyzer,  93 
Diamin,  481,  519 
Diamino-acids,  525 
Diamond,  99 
Diastase,  395,  537 
Diazobenzene  sulphate,  481 
Diazo-compounds,  480 
Diazo-reaction  in  urine,  626 


638 


INDEX 


Dibasic  acids,  162 
Didymium,  117 
Diet,  purin-free,  492 
Dietary  standards,  542 
Diethylamin,  497 
Diffusates,  93 
Diffusion,  92 

of  gases,  92 

of  liquids,  92 
Digestion,  540,  542 
Digitalin,  443 
Dihydric  phenols,  450,  460 
Dimorphism,  152 
Dionin,  513 
Diphenyl,  451,  471 

-amin,  471 
Dippel's  oil,  484 
Disaccharids,  438 
Disinfectants,  140,  157,  406 
Dissociants,  132 
Dissociation,  127 

electrolytic,  95,  128 

hydrolytic,  130,  189,  192,  198,  220,  228 

of  a  dibasic  acid,  163,  182,  220 

of  tribasic  acid,  188 
Distillation,  85 

destructive,  392 

fractional,  378 
Disulphid  of  carbon,  193 
Divisibility,  29 

chemical,  109,  250 
Dolomite,  242 
Donovan's  solution,  287 
Double  salts,  189,  254 
Dried  alum,  254 
Drinking-water,  259 
Ductility,  29 

Dyes,  coar-tar,  harmless,  477 
Dynamite,  431 


EARTHS,  251 

alkaline,  223 
Ecgonin,  503,  507 
Efflorescence,  83 
Ehrlich's  diazo-reaction,  566 
Elasticity,  29 
Elastin,  528 
Electricity,  45 
Electrodes,  46 
Electrolysis,  50,  78,  128 
Electrolyte,  50,  128 
Electrolytic  dissociation,  95,  128 
Electromotive  force,  46 

negative  bodies,  51,  112 

positive  bodies,  51,  112 
Electrons,  46,  54,  63,  109,  in,  250 
Element,  definition,  63,  in 
Elementary  analysis,  363 
Elements,  63 

classification  of,  117 

derivation  of  names  of,  117 


Elements,  metallic,  64 

natural  groups  of,  117 

non-metallic,  63 

typic,  64 

valence  of,  117 

Emanation  from  radium,  248,  251 
Emerald  green,  290 
Emery,  253 

Empirical  formulas,  112,  367 
Emulsin,  446,  464,  539 
Emulsion,  428 
Energy,  17,  73 

Joule's  unit  of,  74 

of  alkali  metals,  236 

of  foods,  539 

of  hydrogen  dioxid,  87 
Enterokinase,  556,  560 
Enzyms,  396,  535,  567 

classification  of,  537 

functions  of,  535 

nomenclature,  537 

oxidizing,  567 
Eosin,  462 
Epiguanin,  489 
Epithelium  in  urine,  560 
Epsom  salt,  244 
Equations,  chemical,  66,  112 

reversible,  82,  433 
Equilibrium,  82,  433 

of  three  phases,  43 

reaction  of,  37,  83 
Equivalence,  125 
Erbium,  117 
Erepsin,  534,  556,  560 
Erythrodextrin,  543 
Erythrosin,  red,  477 
Esbach's  albuminometer,  553 
Esters,  372,  427,  430,  432 
Ethane,  374,  376 
Ethene,  381 
Ether,  17,  58,  403 

acetic,  433 

ethyl,  403 

nitrous,  430 

sulphuric,  403 

as  solvent  of  alkaloids,  521 
detection  of,  405 
fatal  dose  of,  405 

period  of,  405 

postmortem  appearances  after,  405 
properties  of,  404 
symptoms  of,  405 
toxicology,  405 

treatment  in  poisoning  by,  405 
Ethereal  sulphates,  430,  589 

sulphuric  acid,  430,  589 

waves,  58 
Ethers,  371,  402 

compound,  417,  430 

mixed,  402 

simple,  402 
Ethine,  383 


INDEX 


639 


Ethyl  acetate,  83,  428,  433 
alcohol,  395 
bromid,  392 
chlorid,  391 
ether,  403 

hydrogen  sulphate,  404 
hydroxid,  395 
iodid,  392 
mercaptan,  414 
nitrate,  430 
nitrite,  430 
oxid,  403 
sulphid,  430 
sulphonic  acid,  430 
sulphuric  acid,  430 
Ethylamin,  497 
Ethylene,  381 
bromid,  392 
glycol,  401 
Ethylic  alcohol,  395 

cases  of  poisoning  by,  397 
fatal  dose  of,  398 

period  of,  398 
isolation  of,  398 
physiologic  action  of,  397 
postmortem  appearances  after  poi- 
soning by,  398 
properties  of,  397 
symptoms  of  poisoning  by,  397 
tests  for,  398 

treatment  in  poisoning  by,  398 
Eucain,  508 
Eucalyptol,  453 
Euchlorhydria,  547 
Eudiometer,  84 
Evaporation,  39 
Exalgin,  479 

Examination,  clinical,  of     gastric     con- 
tents, 544 
of  milk,  564 
of  urine,  576 

FAHRENHEIT'S  thermometer,  31 

Farad,  49 

Faraday's  laws,  52 

Fats,  426 

Fatty  acids,  417 

Fehling's  solution,  545 

test,  545 
Feldspar,  212 

Fermentation,  395,  444,  535 
Fermented  beverages,  397 
Fermenting  power,  557 
Ferments,  395,  444,  535 
Ferratin,  338 
Ferric  acetate,  342 

chlorid,  340 

citrate,  344 

hydrate,  270,  341 

hydroxid,  270,  341 

ions,  339 

nitrate,  343 


Ferric  oxid,  341 

phosphate,  344 

salts,  tests  for,  347 

sulphate,  342 

sulphocyanate,  345 

tartrate,  344 
Ferricyanids,  345 
Ferricyanogen,  343 
Ferrocyanidion,  345 
Ferrocyanids,  345 
Ferrocyanogen,  345 
Ferrous  carbonate,  343 

chlorid,  340 

-ferric  oxid,  341 

hydroxid,  341 

iodid,  342 

ions,  339 

oxid,  341 

phosphate,  344 

salts,  test  for,  347 

sulphate,  342 

sulphid,  342 
Ferrum,  337 
Feser's  lactoscope,  571 
Fibrin,  528,  533,  553,  562 
Fibrinogen,  528,  562 
Filters,  259,  261 

Pasteur,  260 

town,  259 
Fire-damp,  373 
Flame,  structure  of,  113 

-tests,  222,  239,  241 
Flashing  point,  380 
Fleitmann's  test,  282 
Flowers  of  sulphur,  150 
Fluorescein,  89,  461 
Fluorescence,  58 
Fluorin,  148 
Fluorspar,  148 
Food,  absorption  of,  540 

animal,  540 

energy  of,  540 

fats  of,  541 

fuel  value  of,  541 

plants,  540 

-poisoning,  520 

proteins  of,  540 
Force,  17,  73,  539 
Formaldehyd,  406,  437,  568 
Formalin,  407,  437,  568 
Formamid,  497 
Formic  acid,  406,  409 

aldehyd,  406 
Formin,  498 
Formose,  436 
Formulas,  chemical,  112,  367 

constitutional,  115,  370 

empiric,  112,  367 

graphic,  115,  370 

molecular,  112,  367 

rational,  112 

structural,  370 


640 


INDEX 


Fowler's  solution,  287 
Fractional  distillation,  353 
Fraunhofer's  lines,  56 
Freezene,  408,  568 
Freezing  mixtures,  37 

point,  35,  96 

Fronde's  reaction,  515,  526 
Fructose,  435,  436 
Fruit  essences,  433 
Fruit-sugar,  436 
Fuel  oil,  379 
Fusel  oil,  396,  399 
Fusing  point,  35 


GALACTASE,  567 
Galactose,  437,  439 
Galena,  320 
Gallic  acid,  470 
Gallium,  117,  251 
Gall-stones,  559 
Galvanic  cell,  45 

current,  45 
Galvanized  iron,  353 
Gas  analysis,  84 

definition  of,  29 

illuminating,  372,  382 

natural,  378 

tension,  29 
Gasoline,  379 
Gastric  acids,  546 

contents,  544 

juice,  544 

Gay  Lussac's  law,  30,  in 
Gelatin,  528 
Gelsemium,  516 

fatal  dose  of,  516 
period  of,  516 

separation  from  tissues  and  organs,  521 

symptoms  of  poisoning  by,  516 

tests  for,  516 

toxicology,  516 
Germanium,  117 
German  silver,  357 
Germs  in  milk,  566 

in  stomach,  546 

Gin,  .397 

Glacial  acetic  acid,  409 
phosphoric  acid,  189 
Glass,  206 
Glauber's  salt,  225 
Globin,  527 
Globulin,  527 
Globulose,  533 
Glonoin,  431 
Glucinum,  117 
Gluconic  acid,  436 
Glucoproteins,  527,  531 
Glucosamin,  500,  525,  535 
Glucose,  395,  434,  444,  537 
Glucosids,  443,  464,  539 
Glue,  528 


Glutaric  acid,  421,  525 
Gluten,  440 
Glycerids,  417 
Glycerin,  401,  427 

arsenic  in,  287 

cupric  test  for  glucose,  545 
Glycerites,  402 
Glycerol,  401 
Glyceryl  trinitrate,  431 
Glycin,  465,  499 
Glycocholic  acid,  421,  499 
Glycocoll,  466,  499,  525,  535 
Glycogen,  441 
Glycols,  401,  421 
Glycoproteins,  531 
Glycosuria,  444 
Glycozone,  86 
Glycuronic  acid,  436,  607 
Glyzylalanin,  534 
Gmelin's  test,  559,  560,  618 
Gold,  358 

and  sodium  chlorid,  359 

chlorid,  359 

coin,  358 

sulphid,  359 

tests  for,  359 
Goulard's  extract,  322 
Graham's  law,  92 
Granite,  207 
Grape-sugar,  435 
Graphic  formulas,  115,  370 
Graphite,  99 

Gravimetric  methods,  126 
Gravitation,  18,  62 
Green,  S.  F.,  477 
Green  vitriol,  342 
Guaiac  test,  538,  563 
Guaiacol,  461 
Guanase,  539 
Guanidin,  489 
Guanin,  489,  490,  491,  535 
Guaranin,  490 
Gum,  441 

-arabic,  441 

British,  441 
Gun-cotton,  443 
Gunpowder,  217 

smokeless,  458 
Giinzburg's  test,  549 
Gypsum,  241 

H^EMATIN,  529 

Haematoidin,  530 
Haemin,  529,  563 

crystals,  529 
Haemoglobin,  529 
Halids,  371 
Halogen    derivatives   of    hydrocarbonsr 

371-  384 
Halogens,  149 
Haloids,  149 
Hardness  of  water,  240 


INDEX 


641 


Harle's  solution,  287 
Hartshorn,  232 
Heat,  28 

action  upon  compounds,  65 
matter,  28 
organic  substances,  363 

atomic,  35 

capacity,  34 

decomposition  by,  364 

latent,  36 

of  decomposition,  73 

of  oxidation,  73 

specific,  34 
Heavy  magnesia,  243 
Hehner  and  Richmond's  formula,  571 
Hehner's  test  for  formaldehyd,  569 
Helium,  98,  249 
Helleborin,  443 
Heller's  test,  610,  617 
Hematin,  529 
Hematite,  337 
Hematoidin,  530 
Hematoporphyrin,  530,  581 
Hematuria,  616 
Hemin,  529,  563 
Hemlock,  503,  504 
Hemoglobins,  529 
Hemoglobinuria,  617 
Hemolysin,  524,  563 
Henbane,  503,  506 
Henry's  law,  91,  123 
Hepar  sulphuris,  219 
Heroin,  513 

Heterocyclic  compounds,  448,  483 
Heteroxanthin,  450 
Hexagonal  system  of  crystals,  153 
Hexamethylenamin,  498 
Hexane,  376 
Hexons,  525,  527 
Hexoses,  434 
High  wines,  396 
Hippuric  acid,  465,  535 
Histidin,  525,  527 
Hoffman's  anodyne,  405 
Homatropin,  506 
Homologous  series,  377 
Humidity  of  the  air,  relative,  85,  86 
Hydracids,  139 
Hydrargyri  massa,  307 

oleatum,  309 

unguentum.  307 
Hydrargyrum,  306 

cum  creta,  307 
Hydrastin,  503 
Hydrates,  84 
Hydrazin,  481 
Hydrazo-compounds,  481 
Hydrazones,  481 
Hydriodic  acid,  147 

ether,  392 
Hydrion,  131 
Hydrobromic  acid,  144 


Hydrobromic  ether,  399 
Hydrocarbons,  371,  376 
nomenclature,  377 
saturated,  376 
unsaturated,  381,  382 
Hydrochloric  acid,  135 
detection  of,  139 
fatal  dose,  137 

period,  137 

in  gastric  contents,  546 
poisoning,  postmortem  appearances, 

138 

symptoms  of,  138 
treatment,  138 
properties  of,  136 
test  for  silver,  136 
tests  for,  138 
toxicology,  137 
Hydrocyanic  acid,  194 
antidotes  to,  196 
cases  of  poisoning  by,  196 
estimation  of,  198 
fatal  dose,  195 
isolation  of,  198 
physiologic  action  of,  196 
postmortem  findings  after,  197 
properties  of,  195 
symptoms  of  poisoning  by,  196 
tests  for,  197 

treatment  in  poisoning  by,  87,  196 
Hydroferricyanic  acid,  345 
Hydroferrocyanic  acid,  344 
Hydrofluoric  acid,  148 
Hydrogen,  77 
arsenid,  265 
arseniuretted,  265 
chlorid,  122 
dioxid,  86 
fluorid,  148 
iodid,  147 
peroxid,  86 
phosphid,  187 
phosphoretted,  187 
sulphid,  154 

group  reagent,  156 
toxicology  of,  157 
sulphuretted,  154 
Hydrolysis,  130,  189,  192,  198,  220,  228, 

427,  535 

Hydrometers,  26 
Hydropyridins,  484 
Hydroquinon,  450,  462 
Hydrosulphuric  acid,  156 
Hydroxidion,  131,  135 
Hydroxyl,  82,  131 
Hydruria,  580 
Hygrins,  503 
Hygrometer,  86 
Hyoscin,  503,  506 
Hyoscyamin,  503,  506 
Hynerchlorhydria,  547 
Hypertonic,  96 


642 


INDEX 


Hypobromite  method  of  estimating  urea, 

593 

Hypobromites,  144 
Hypochlorhydria,  547 
Hypochlorites,  tests  for,  141 
Hypochlorosion,  141 
Hypochlorous  acid,  140 

oxid,  141 

Hypodermoclysis,  96 
Hyponitrous  acid,  175 
Hypophosphites,  tests  for,  191 
Hypophosphorous  acid,  191 
Hyposulphurous  acid,  168 
Hypotonic,  96 
Hypoxanthin,  489 

ICHTHYOL,  458 

Illuminating  gas,  100 

oil,  379 

Imido-compounds,  498 
Imins,  498 
Immunity,  522 
Indestructibility,  70 
Indican,  487,  581 
Indicators,  124,  130 
Indigo,  486 

-blue,  486,  581 

disulphacid,  477 

-red,  486,  487 
Indigotin,  486 
Indium,  117 
Indol,  487,  525,  535 
Indophenol  reaction,  479 
Indoxyl,  486,  581 
Induced  electricity,  53 
Induction  coil,  52 
Infection  toxins,  522 
Infraproteins,  527,  532 
Inorganic  compounds,  64 
Inosite,  437 
Intestinal  juice,  559 
Intra-atomic  matter,  250 
Invertase,  438,  538,  557,  560 
Inverted  sugar,  436 
Inverting  enzyms,  538,  560 
lodic  acid,  147 

lodids,  analytical  reactions  of,   146 
lodimetry,  127 
lodin,  144 

tests  for,  147 

tincture  of,  145 

toxicology,  146 
detection  of,  147 
fatal  dose  of,  146 
in  solution   of   potassium    iodid    as 

reagent  for  alkaloids,  502 
postmortem  appearances  after,  147 
symptoms  of  poisoning  from,  146 
treatment  of  poisoning  from,  146 
lodism,  147 
Iodized  starch,  146 
lodoform,  390 


lodoform,  toxicology,  390 

detection  of,  391 

postmortem  appearances  after,  391 

symptoms  of  poisoning  from,  390 

treatment  in  poisoning  by,  390 
lodol,  483 
Ion  formation,  first  mode,  119 

fourth  mode,  340 

second  mode,  301 

third  mode,  359 
theory,  52,  131 

Ions,  50,  52,  114,  128,  134,  301 
dissociation  of,  128 
of  cyanids,  135 
of  indicators,  130 
of  sulphates,  135 
Iridium,  359 
Iron,  337 
acetate,  346 

analytic  reactions  of,  347 
carbonate,  316 
cast-,  338 
chlorids,  339,  340 
citrate,  344 
dialyzed,  341 
galvanized,  353 
hydroxids,  270,  341 
iodid,  342 
nitrate,  343 
ores,  337 
oxids,  341 
phosphates,  344 

Pig,  338 

pyrites,  337 

reduced,  339 

scale,  compounds  of,  344 

sulphates,  342 

sulphid,  342 

tannate,  347 

tartrate,  344 

toxicology  of  salts,  346 

trioxid,  339 

wrought,  338 
Isatin,  486,  581 

Isobenzonitril,  388,  477,  478,  498 
Isobutane,  375 

Isocyclic  compounds,  448,  483 
Isomerism,  no,  200,  376 
Isomorphism,  153 
Isonitril,  388 
Isoquinolin,  488,  503 
Isosmotic,  96 
Isotonic,  96 

JABORANDI,  503,  504 

Jaffe's  test,  487 

Jervin,  515 

Joule's  unit  of  energy,  50,  74 

KAINITE,  242  - 
Kairin,  488 


INDEX 


643 


Kalium,  212 
Kaolin,  251 

cataplasm  of,  251 
Kelling's  test,  552 
Kelp,  141 
Kephir,  440 
Keratin,  528 
Kermes  mineral,  291 
Kerosene,  379 
Ketones,  413 
Ketoses,  434 
Kilojoules,  50,  74 
Kinetic  theory,  29 
Kippenberger  process,  521 
Kjeldahl's  method,  365,  595 
Knop's  fluid,  592 
Kreatinin,  494,  553 
Krypton,  98 
Kumyss,  439 

LABARRAQUE'S  fluid,  141 

Lactalbumin,  527,  566 

Lactase,  538 

Lactic  acid,  422,  546,  552,  565 

Lactoglobulin,  528,  566 

Lactometer,  569 

Lactoscope,  571 

Lactose,  438,  565 

Laevorotation,  59,  436 

Lamp  black,  99 

Lanolin,  558 

Lanthanum,  117,  251 

Lapis  infernalis,  335 

Lard,  426 

Latent  heat  of  fusion,  35 

of  vaporization,  41 
Laughing-gas,  176 
Lavage  test,  555 
Law,  Avogadro's,  77,  95 

Boyle's,  107 

Charles's,  30,  107 

of  chemical  combination  by  volume, 

in 

by  weight,  69,  108 
equilibrium,  82,  433 

of  the  conservation  of  energy,  70 

of  constancy  of  composition,  69,  108 

of  Dalton,  108 

of  definite  proportions,  70,  108 

of  diffusion  of  gases,  92 

of  Dulong  and  Petit,  35 

of  equivalent  proportions,  71,  109 

of  Faraday,  51 

Gay-Lussac's,  30,  in 

Graham's,  92 

Henry's,  91,  123 

Mariotte's,  39 

of  mass-action,  82 

Mendelejeff's,  116,  150 

of  multiple  proportions,  108 

periodic,  116 

of  Raoult,  38,  368 


Lead,  320 
acetate,  323 
antidotes  to,  324 
carbonate,  322 
chlorid,  322 
chromate,  323,  325 
dioxid,  321 
iodid,  328 
ions  of,  321 
nitrate,  322 
oleate,  321 
oxid,  321 
plaster,  321 
red,  321 
sugar  of,  323 
sulphate,  322 
toxicology,  323 

detection  of,  by  electrolysis,  328 
in  gastric  contents  and  tissues,  329 
in  urine,  329 
fatal  dose,  324 

period,  324 
poisoning,  acute,  324 
causes  of,  325 
chronic,  325 

distribution  of  lead  in  tissues,  327 
postmortem    appearances    after, 

324,  327 

symptoms  of,  323,  325 
poisonous  salts  of,  323 
quantitative  estimation  of,  330 
tests  for,  328 
treatment  in   poisoning,  acwte, 

324 

-water,  322 

white,  322 
Lecithin,  517,  519 
Leclanche  cell,  47,  348 
Legal's  test,  607 
Leucin,  499,  623 
Leucomains,  '517 
Leucylprolin,  485 
Leukocytes,  561 
Levulose,  436 
Liebermann's  reaction,  526 
Liebig's  condenser,  379 
Light,  decomposition  by,  335 

magnesia,  243 
Ligroin,  379 
Lime,  acid  phosphate  of,  241 

chlorated,  239 

chlorid  of,  239 

-kiln,  237 

liniment,  238 

milk  of,  238 

quick,  236 

slaked,  237 

superphosphate  of,  241 

syrup  of,  238 

-water,  238 
Limestone,  237,  240 
Lipases,  429,  538,  545,  557,  567 


644 


INDEX 


Lipolytic  enzyms,  538 
Liquefaction  of  solids,  35 
Liquid  air,  108 
Liquids,  definition  of,  34 
Liquor  acidi  arsenosi,  267 

ammonii  acetatis,  234 

antisepticus,  209 

arseni  et  hydrargyri  iodidi,  287 

calcii  bicarbonatis,  240 

chlori  compositus,  120 

ferri  chloridi,  340 

magnesii  citratis,  244 

potassii  arsenitis,  267 
citratis,  221 

sodae  chlorinatae,  141 

sodii  arsenatis,  287 
arsenitis,  287 

phosphatis  compositus,  227 
Litharge,  321 
Lithium,  230 

bromid,  230 

carbonate,  230 

citrate,  230 

urate,  230 
Litmus,  123 

solution,  123 
Loadstone,  45 
Lubricating  oil,  379 
Lugol's  solution,  145 
Lunar  caustic,  335 
Lutidin,  485 
Lye,  concentrated,  224 
Lymph,  562 
Lymphocytes,  561 
Lysidin,  489 

Lysin,  499,  500,  525,  527 
Lysins,  522 

auto-,  523 

hemo-,  523,  563 

hetero-,  523 

homo-,  523 
Lysol,  460 


MADDER,  artificial,  474 
Magnalium,  252 
Magnesia,  243 

calcined,  243 

mixture,  586 
Magnesite,  242 
Magnesium,  242 

analytical  reactions  of,  244 

carbonate,  243,  244 

citrate,  244 

hydroxid,  243 

oxid,  243 

sulphate,  244 

Magnetic  iron  ore,  45,  341 
Magnetism,  45 
Malachite,  300 
Malleability,  210 
Maltase,  439,  538,  543 


Malting,  395 

Maltose,  83,  395,  439,  537,  538,  543 

Manganates,  348 

Manganese,  347 

analytical  reactions  of,  350 

black  oxid  of,  348 

dioxid,  1 1 8,  348 

ions  of,  348 

oxids  of,  348 
Manganic  acid,  348 
Manganous  carbonate,  349 

hydroxid,  350 

oxid,  118,  348 

sulphate,  348 

sulphid,  348 
Marble,  237,  240 
Margaric  acid,  420 
Mariotte's  law,  39 
Marsh-gas,  372 
Marsh's  test,  279,  295 
Mass,  1 8 

-action,  82 
Mastication,  542 
Matches,  177 
"Materna,"  573 
Matter,  definition  of,  17 
Measures,  19 
Meconic  acid,  512 
Meerschaum,  242 
Melissic  acid,  409 
Melting-points,  34 
Mendelejeffs  law,  116,  150 
Menthol,  453 
Mercaptans,  414 
Mercaptols,  415 
Mercurial  ointment,  307 

plaster,  307  _ 
Mercuric  chlorid,  309 

cyanid,  194,  199 

iodid,  311 

nitrate,  313 

oxid,  308 

potassium  iodid,  312,  318 

sulphate,  313 

sulphid,  312,  318 
Mercurous  chlorid,  309 

iodid,  311 

nitrate,  313 

oxid,  308 

salts,  tests  for,  317 

sulphate,  313 

sulphid,  312,  318 
Mercury,  306 

ammoniated,  313 

antidotes  to,  315 

basic ^  sulphate,  313,  315 

chlorids,  309 

iodids,  311 

ions  of,  307 

nitrates,  313 

oleate,  309 

oxids,  308 


INDEX 


645 


Mercury  sulphates,  313,  315 
sulphids,  312,  318 
toxicology,  314 

chronic  poisoning  from,  315 

postmortem     appearances     after, 

3*5,  310 

treatment,  315,  316 
detection  of,  319 
distribution  in  tissues,  318 

in  urine,  320 

quantitative  determination  of,  317 
separation  of,  319 

by  electrolysis,  319 
tests  for,  317 
Metabolism,  540 
Meta-compounds,  449 
Metaglobulin,  562 
Metallic  elements,  210 
Metallo-cyanides,  199 
Metalloids,  65 
Metals,  210 

classification  of,  218,  236 
derivation  of  names,  117 
melting-points,  34 
separation  of,  211 
specific  gravity,  211 
valence,  114 
Metamerism,  408 
Metaphosphoric  acid,  189 
Meta-position,  449 
Methacetin,  480 
Methane,  372,  376 

series,  372 

Methemoglobin,  530 
Methyl  acetanilid,  479 
alcohol,  392 
aldehyd,  406 
amin,  497 
anilin,  478 
benzene,  446,  451 
blue,  477 
chlorid,  384,  385 
hydroxid,  392 
toxicology,  393 
detection  of,  394 
fatal  dose  of,  393 

period  of,  393 

symptoms  of  poisoning  by,  393 
treatment  in  poisoning  by,  394 
orange,  124 
salicylate,  469 
Methylated  spirit,  393 
Methylene  blue,  477 
Methylpiperidin,  485 

chlorid,  384,  385 
Methylthionin  hydrochlorid,  477 
Metric  system,  20 
Metrology,  17 
Mica,  242 
Michel's  paste,  162 
Microcidin,  473 
Microcosmic  salt,  235 


Milk,  439,  564 

adulterations  of,  210,  568 
analysis  of,  564 
casein  of,  565 
curds,  566 
modified,  572 
morbid,  564 
Pasteurized,  567 
peptonized,  566 
preservation  of,  210,  566,  568 
reaction  of,  564 
standards  of,  573 
sterilization  of,  566 
-sugar,  439,  565 
testing  by  Adam's  method,  576 
by  Babcock's  method,  574 
by  Werner-Schmid  method,  574 
Millon's  reagent,  457,  500,  527 
Mineral  water,  85,  256 
Minium,  321 
Mirbane,  oil  of,  475 
Mistura  cretae,  240 

magnesiae  et  asafcetidse,  244 
potassi  citratis,  221 
Molasses,  438 
Molecular  motion,  28 
theory,  28 
weight,  in,  368 
Molecule,  definition  of,  28,  76 
Molisch's  test,  434,  473,  500,  527 
Molybdenum,  362 
Molybdic  acid,  362 

oxid,  362 

Monazite  sand,  361 
Monobasic  acids,  162 
Monoclinic  system,  152 
Monosaccharids,  434 
Monoses,  434 
Monsel's  solution,  342 
Morphin,  503,  512 
acetate,  513 
hydrochlorate,  513 
sulphate,  513 
toxicology,  513 

chronic  poisoning  by,  514 
description  of,  512 
fatal  dose  of,  514 

period  of,  513 
maximum      medicinal      doses     for 

adults,  514 
meconic  acid  in,  512 
postmortem  appearances  after,  514 
separation  of,  from  tissues,  521 
symptoms  of  poisoning  by,  513 
tests  for,  514 

treatment  of  poisoning  from,  514 
Morpholin,  514 
Mortar,  237 
Mucilage  of  starch,  440 
Mucin,  531 
Mucoids,  531 
Mucose,  531 


646 


INDEX 


Mucus,  531 

Mulberry  calculus,  592 
Murexid  test,  489,  491,  598 
Muriatic  acid,  135 
Muscarin,  517,  519 
Muscle  sugar,  437 
Mushroom  poisoning,  517 
Mustard  oil,  539 
Mycoderma  aceti,  396,  419 
Mydalein,  517,  519 
Myoalbumin,  527 
Myoglobulin,  528 
Myosin,  528 
Myronic  acid,  539 
My  rosin,  539 
Mytilotoxin,  517,  518 


NAPHTHA,  379 

drunk,  380 

Naphthalene,  445,  471 
Naphthalin,  445,  471 
Naphthol,  473 
beta-,  473 
yellow  S,  477 
Naphthosalol,  474 
Narcein,  503,  512 
Narcotin,  512 
Nascent  state,  77,  113 
Natrium,  223 
Natural  gas,  378 
Neon,  98 
Nepenthe,  512 
Nessler's  solution,  312 
Neuridin,  517,  519 
Neurin,  517,  519 
Neutral  mixture,  221 
salts,  162 
substances,  124 
Neutralization,  124 
Nickel,  357 
Nicotin,  503,  505 
toxicology,  505 

and  ptomains,  517 
chemical  tests  for,  506 
poisoning  from,  505 
symptoms  of  poisoning,  505 
treatment  in  poisoning  by,  506 
Nicotinic  acid,  484,  505 
Niobium,  117 
Niter,  217 

Nitrates,  analytical  reactions  of,  172 
Nitric  acid,  169 
toxicology,  171 
detection  of,  172 
fatal  dose  of,  171 

period  of,  171 
fumes  of,  173 

poisoning,    postmortem    appear- 
ances after,  171 
symptoms  of,  171 
treatment  of,  171 


Nitric  acid,  properties  of,  169 
tests  for,  172 

ether,  430 

oxid,  174 

Nitrifying  bacteria,  174 
Nitrites,  176 
Nitro-benzene,  475 

toxicology,  475 
detection  of,  476 
fatal  dose  of,  475 
physiologic  action  of,  475 
postmortem  findings  after,  475 
treatment  in  poisoning  by,  475 
Nitro-cellulose,  443 
Nitrogen,  97,  169 

combined,  97,  541 

content,  365,  541 

derivatives  of  benzene,  475 

determination,  365 

monoxid,  176 

oxids,  174 

tetroxid,  175 
Nitrogenous  foods,  540 
Nitroglycerin,  431 

tests  for,  432 

toxicology  of,  432 
Nitrohydrochloric  acid,  173 
Nitro-muriatic  acid,  173 
Nitrous  acid,  175 

ether,  430 

oxid,  176 
Noble  gases,  98 
Nomenclature,  108 

of  acids,  131 

of  hydrocarbons,  377 

of  ions,  131 

Non-metallic  elements,  65 
Nonoses,  434 

Nordhausen  sulphuric  acid,  162 
Normal  salts,  162 

salt  solution,  101,  225 

solutions,  125 
Notation,  65,  108 
Nucleases,  492,  538 
Nucleic  acid,  492,  532 
Nuclein  bases,  490 
Nucleinic  acid,  532 
Nucleins,  490,  492,  531,  532 

para-,  527,  532 

pseudo-,  527,  532 
Nucleo-albumin,  531 

-histon,  527,  532 

-proteins,  527,  532 
Nutrose,  566 
Nux  vomica,  503,  510 
Nylander's  reagent,  603 

OBLIQUE  system  of  crystals,  152 
Occluded  gas,  81 
Ohm,  49 

Oil,  bitter  almond,  194,  464 
bone,  484 


INDEX 


647 


Oil,  burning,  379 
cotton-seed,  428 
fuel,  379 
illuminating,  379 
olive,  428 
paraffin,  379 
rock,  378 
turpentine,  452 
vitriol,  1 60 
wintergreen,  467,  469 
Oils,  fat,  426 
lubricating,  379 
mustard,  528 
Olefiant  gas,  381 
Olefins,  381 
Oleic  acid,  421 
Olein,  428 
Oleomargarin,  428 
Oliguria,  580 
Olive  oil,  428 
Opium,  502 

-alkaloids,  503,  512 
Opsonins,  523 
Orange  I,  477 
Orcin  test,  606 
Organic  analysis,  363 
chemistry,  64,  363 

substances,  classification  of,  363,  371 
decomposition  of,  363 
formation  of,  in  plants,  363 
Ornithin,  499,  525 
Orpiment,  291 
Ortho-compounds,  449 
Orthophosphoric  acid,  188 
Ortho-position,  449 
Orthorhombic  system  of  crystals,  154 
Osazone,  434,  481 
Osmium,  359 
Osmosis,  94 
Osmotic  pressure,  95 
Ossein,  528 
Ovalbumin,  527 
Oxalates,  reactions  of,  203 
Oxalic  acid,  200,  421 
antidotes  to,  203 
toxicology,  20 1 
detection  of,  204 
fatal  dose  of,  202 

period  of,  203 

poisoning,     postmortem     appear- 
ances, 202 
symptoms  of,  201 
treatment  of,  203 
properties  of,  201 
tests  for,  203 
Oxamid,  88,  196 
Oxidases,  538 
Oxidation,  energy  of,  74 
Oxidimetry,  126 
Oxidizing  enzyms,  538,  567 

reagents,  122 
Oxids,  69 
Oxone,  66 


Oxyacids,  139 

Oxy butyric  acid,  422 

Oxygen,  65 

derivatives,  392 

in  blood,  562 
Oxygenases,  538 
Oxy  hemoglobin,  529,  530 
Oxyprolin,  525 
Ozone,  74 
Ozonic  ether,  86 


PALLADIUM,  359 
Palmitic  acid,  427 
Palmitin,  427 
Pancreas,  555 
Pancreatic  juice,  555 
ferments  of,  556 
Pancreatin,  557 
Papaverin,  503,  512 
Paper,  442 

parchment-,  442 
Para-compounds,  449 
Paradiazin,  486 
Paraffin,  373,  378,  399 

oil,  379 

Para-formaldehyd,  407 
Paraglobulin,  562 
Paraldehyd,  401 

toxicology,  401 
Para-position,  449 
Paraxanthin,  489 
Paris  green,  290,  303 
Pasteurization,  396,  567 
Pearlash,  220 
Pearl-white,  342 
Pear  oil,  433 
Pearson's  solution,  287 
Peat,  99 
Pelletierin,  503 
Pental,  382 
Pentane,  376 
Pentene,  381,  382 
Pentose,  434,  437,  606 
Pepsin,  534,  537,  545,  553>  566 
Peptic  activity,  555 
Peptones,  527,  533,  566 
Peptonized  milk,  566 
Perchloric  acid,  140 
Periodic  acid,  148 

law,  150 

Permanganates,  348 
Peroxidases,  538,  563 
Petrolatum,  379 
Petroleum,  378 

-ether,  379 

toxicology  of,  380 
Pettenkofer's  test,  558,  560 
Pewter,  320 
Phagocytes,  523,  562 
Phase  rule,  43 
Phenacetin,  479 
Phenanthrene,  474,  504,  512 


648 


INDEX 


Phenazone,  481 
Phenetidin,  479 
Phenol,  453,  525>  535 

acids,  467 

dihydric,  452,  461 

phthalein,  467 

sulphonic  acid,  458 

trihydric,  462 

trinitro-,  458 
Phenyl-acetamid,  478 

-acetanilid,  478 

-alanin,  525 

-amin,  476 

hydrate,  453 

hydrazin,  481 

salicylate,  469 
Philosophy,  chemical,  108 
Phlorhizin,  443 
Phloroglucin,  463,  549 
Phosgene  gas,  192,  386 
Phosphates,  analytical  reactions  of,  189 
Phosphin,  185,  187 

Phosphites,  analytical  reactions  of,  190 
Phosphoglucoproteins,  532 
Phospho-molybdic  acid,  189,  362 
Phospho-proteins,  527,  528 
Phosphoretted  hydrogen,  187 
Phosphoric  acids,  188 

anhydrid,  187 
Phosphorous  acid,  190 
Phosphorus,  177 

antidotes  to,  181 

chlorids,  191 

content,  367 

detection  of,  183 

determination  in  organic  compounds, 

367 

oxids,  187 

red  or  amorphous,  177 
terhydrid,  187 
toxicology,  178 
fatal  dose  of,  180 

period  of,  180 
necrosis,  182 
phosphorescence    of,    in    hydrogen, 

1 86 
poisoning,  chronic,  182 

postmortem  appearances,  181 
symptoms,  180 
treatment  of,  181 
postmortem  recognition  of,  182 
preparations  of,  178 
properties  of,  177 
quantitative  estimation  of,  183 
symptoms,  179 
tests  for,  183 
treatment,  181 
Photography,  335 
Phthalic  acid,  466 
Physical  forces,  62 
Picolin,  485 
Picric  acid,  458,  611 


Picrotoxin,  521 
Pilocarpin,  503,  504 
Pineapple  oil,  433 
Pioscope,  571 
Piperazin,  485,  489 
Piperidein,  485,  503 
Piperidin,  485,  503,  504,  506 
Piperin,  485,  503 
Pipets,  126 
Pitch,  446 

blende,  361 
Plasmon,  566 
Plaster-of -Paris,  241 
Platinum,  359 

and  ammonium  chlorid,  360 

and  potassium  chlorid,  360 

black,  360 

chlorids,  360 

colloidal,  87,  360 

sponge,  81,  360 
Plumbago,  99 
Plumbum,  320 
Plummer's  pill,  291 
Pneumaturia,  624 
Point,  boiling,  369 

flashing,  379 
Polarimeter,  58 

with  urine,  61 
Polarized  ray,  59 
Polymerism,  408 
Polymorphism,  152 
Polynucleated  compounds,  451,  471 
Polypeptids,  524,  527,  534 
Polysaccharids,  440 
Polyuria,  581 
Poppy,  512 
Porosity,  28 
Port  wine,  397 
Porter,  397 
Potash,  213 

caustic,  214 
Potassa,  213 

cum  calce,  214 

fusa,  214 
Potassium,  212 

acetate,  221 

acid  carbonate,  220 
oxalate,  261 
sulphate,  219 
tartrate,  222 

analytic  reactions  of,  215,  222 

auricyanid,  358 

bicarbonate,  220 

bichromate,  351 

bisulphate,  219 

bitartrate,  222 

bromid,  215 

carbonate,  220 

chlorate,  140,  216 
toxicology  of,  216 

chlorid,  215 

chromate,  351 


INDEX 


649 


Potassium  citrate,  221 
cyanate,  199 
cyanid,  198 
dichromate,  351 
dioxid,  212 
ferricyanid,  199 
ferrocyanid,  199 
hydrate,  213 
hydrosulphid,  219 
hydroxid,  213 

antidotes  for,  275 
toxicology  of,  214 
detection  of,  215 
fatal  dose,  214 
fatal  period,  214 

poisoning,    postmortem    appear- 
ances, 215 
preparations  of,  214 
properties  of,  212 
symptoms  of,  214 
tests  for,  215,  222 
iodid,  216 
manganate,  349 
monosulphid,  219 
nitrate,  217 
nitrite,  218 
oxalate,  201 
permanganate,  349 
phenol  sulphonate,  458 
picrate,  458 
prussiate,  345 
sodium  tartrate,  229 
sulphate,  219 
sulphite,  220 
sulphocyanate,  543 
sulphocyanid,  543 
sulphurated,  219 
tartrate,  222 

tests  for,  222 
thiocyariate,  543 
Precipitate  of  mercury,  308 
red,  308 
white,  312 
yellow,  309 

Precipitation  of  proteins,  526 
Precipitins,  522,  563 
Preliminary  examination  of  urine,  576 
Preservalene,  408,  568 
Preserved  milk,  568 
Pressure  of  air,  107 

of  gases,  29,  40 
Prolin,  485,  525 
Proof-spirit,  395 
Propane,  375,  376 
Propene,  381 
Propenyl  alcohol,  401 
Propine,  382 
Propionic  acid,  417 
Propylene,  381 
Protamins,  527 
Proteases,  537,  545 
Proteids,  524 


Proteins,  524 

coagulated,  533 

compound,  524 

derived,  524 

molecule,  524 

native,  524 

simple,  524 

Proteolytic  enzyms,  537,  545 
Proteoses,  527,  533 
Protons,  527 
Prussian  blue,  345 
Prussiate  of  potash,  red,  345 

yellow,  344 
Prussic  acid,  194 
Pseudo  morphin,  514 
Ptomains,  500,  517 

symptoms   like    alkaloidal    poisoning, 
500 

toxicology,  500 
Ptyalin,  537,  543,  556 
Pulvis  effervescens  compositus,  229 
Purdy's  tests,  546,  554 
Purin  bases,  489,  535,  539,  599 

bodies,  489-535,  539,  599 
Purinometer,  493 
Pus  in  urine,  618 
Putrefaction,  396,  525 
Putrescin,  500,  517,  519 
Putty  powder,  299 
Pykno meter,  25 
Pyocyanin,  518 
Pyoktannin-blue,  477 
Pyrazin,  486 
Pyridin,  483,  503,  504,  505 

homologues,  485 
Pyrimidin,  491 

bases,  491 

nucleus,  491 
Pyrites,  copper,  300 

iron,  337 

Pyrocatechin,  450,  460 
Pyrogallic  acid,  462 
Pyrogallol,  422 
Pyroligneous  acid,  419 
Pyrolusite,  347 
Pyrophosphoric  acid,  188 
Pyroxylin,  442 
Pyrrole,  483,  485 
Pyrrolidin,  485,  503,  505,  506 
Pyuria,  618 


QUADRATIC  system  of  crystals,  153 

Quanti  valence,  114 

Quartz,  205 

Quicklime,  237 

Quicksilver,  306 

Quinidin,  508 

Quinin,  508 

acid  sulphate,  509 

citrate  of  iron  and,  344 

sulphate,  509 


650  INDEX 


Quinin,  tests  for,  509 
Quinol,  450,  462 
Quinolin,  488,  503,  508 

RACEMIC  acid,  423 

Radical,  compound,  definition  of,  194, 

377 

list  of,  385 

simple,  definition  of,  194 
Radio-activity,  109,  247,  249,  251,  361 
Radium,  247 

chlorid,  247 
Ragsky  test,  389 
Ratsbane,  266 
Rays,  light,  58 
alpha,  248 
Becquerel,  247,  361 
beta,  248 
cathode,  54,  248 
Hertzian,  58 
Lenard,  54 
polarized,  58 

Rontgen,  53,  58,  248,  361 
ultra-red,  58 
ultra-violet,  58 
Reactions,  70,  114 
acid,  124 
alkaline,  125 

amphoteric,  498,  564,  579 
of  urine,  579,  584 
Realgar,  291 
Rectified  spirit,  396 
Red  iodid  of  mercury,  311 
lead,  321 
oxid  of  copper,  302 

mercury,  308 
phosphorus,  177 
precipitate,  308 
Reduced  iron,  82,  339 
Reducing  enzyms,  539 
Reductases,  539 
Reduction  by  carbon,  100 
by  hydrogen,  82 
by  sulphur  dioxid,  159 
Refrigeration,  396 

of  milk,  566 

Regular  system  of  crystals,  152 
Reinsch's  test,  271 

for  antimony,  277,  295 
for  arsenic,  277 
for  mercury,  277,  318 
Rennet,  545,  554 
Rennin,  538,  545,  554 
Residue,  definition  of,  194 
Resorcin,  450,  461,  549 
Reversible  processes,  82 
Rheostat,  50 
Rhigolin,  379 
Rhodium,  117 
Ricord's  paste,  162 
Riders,  18 

Robert's  test  for  glucose,  604 
Rochelle  salt,  229 


Rock-candy,  438 

-crystal,  205 

Rontgen  rays,  53,  58,  248,  361 
Rosanilin,  477 

chlorid,  477 
Rubidium,  231 
Ruby,  253 
Rum,  397 
Ruthenium,  117 

SACCHARASE,  538 

Saccharates,  438 

Saccharic  acid,  436 

Saccharids,  434 

Saccharimetry  by  polariscope,  61,  435, 

438 

Saccharin,  482 
Saccharobioses,  434 
Saccharomyces,  396 
Saccharose,  438,  538 
Sahli's  desmoid  test,  555 
Sal  ammoniac,  234 

prunelle,  217 

sodas,  227 
Saleratus,  221 
Salicin,  443,  467 
Salicylic  acid,  467 
Salicyl-sulphonic  acid,  615 
Salipyrin,  469 
Saliva,  543 
Salkowski's  test,  560 
Salmin,  527 
Salol,  469 
Salophen,  469 
Salt,  common,  225 

microcosmic,  235 
Saltpeter,  212,  217 

Chili,  225 
Salts,  acid,  163 

definition  of,  124,  130 

neutral,  162 

normal,  162 
Salvarsan,  287 
Sand,  205 

filters,  252 
Saponification,  427 
Sapphire,  253 
Saprin,  517 

Sausage  poisoning,  520 
Scale  compounds  of  iron,  344,  425 
Scandium,  117,  251 
Scheele's  green,  303 
Schiff  s  fuchsin  reaction,  409 
Schbnbein's  test,  75 
Schweinfurth's  green,  303 
Scleroproteins,  527,  528 
Scopolamin,  506 
Secretin,  555 
Seidlitz  powder,  229 
Selenite,  241 
Selenium,  168 
Serin,  500,  525 
Serpentin,  242 


INDEX 


651 


Serum,  527 

albumin,  527,  562,  609 

globulin,  528,  562,  609 
Sherry  wine,  397 
Siemen's  induction  tube,  74 
Silica,  206 
Silicates,  206 
Silicic  acid,  206 
Silicium,  205 
Silicon,  205 

chlorid,  207 

dioxid,  206 

fluorid,  207 

hydrid,  207 
Silver,  333 

antidotes  to,  336 

bromid,  335 

chlorid,  334 

chromate,  337 

colloidal,  333 

cyanid,  336 

German,  357 

iodid,  337 

ion  of,  334 

nitrate,  335 

oxid,  334 

sulphid,  337 

toxicology,  336 
Sinigrin,  443 

Skatol,  487,  500,  525,  535 
Skiagraph,  54 
Slaked  lime,  237 
Slate,  251 
Soap,  427 
Soapstone,  242 
Soda,  224 

-ash,  225 

-lime,  237 
Sodium,  78,  223 

amino-phenyl  arsenate,  287 

arsenate,  287 

bicarbonate,  228 

bisulphate,  225 

borate,  209 

bromid,  225 

cacodylate,  287 

carbonate,  227 

chlorate,  141 

chlorid,  225 

dimethyl  arsenate,  287 

fluorid,  148 

hydrate,  224 

hydroxid,  224 
toxicology,  224 
detection  of,  225 
fatal  dose,  224 

period,  224 
poisoning,    postmortem 

ances  after,  225 
properties  of,  224 
symptoms,  224 
tests  for,  225,  229 


appear- 


Sodium  hydroxid,  toxicology,  treatment 
of,  224 

hypobromite,  593 

hypochlorite,  141 

hypophosphite,  191 

hyposulphite,  168 

iodid,  225 

nitrate,  225 

nitroprussid,  346 

peroxid,  66,  224 

phenol  sulphonate,  458 

phosphate,  225 

-potassium  tartrate,  229 

salicylate,  467 

sesquicarbonate,  228 

silicate,  206 

sulphate,  225 

sulphite,  1 68 

sulphocarbolate,  458 

thiosulphate,  168 
Solder,  soft,  298,  320 
Soldering  fluid,  355 
Solids,  definition  of,  28 
Solute,  89,  90,  91 
Solution,  89 

concentration  of,  90 

of  gases  in  gases,  92 
in  liquids,  91 

of  liquids  in  gases,  92 
in  liquids,  91 

of  solids  in  liquids,  90 

-tension,  301 
Solutions,  mixed,  134 

saturated,  90 

supersaturated,  91 
Solvent,  90 
Sozolic  acid,  458 
Sparteine,  501 
Spasmotoxin,  518 
Specific  gravity,  22 

heat,  34 

weight,  22 
Spectroscope,  56 
Spectrum  analysis,  56 

of  blood,  101,  531,  564 
ol  elements,  56 
Spermatozoa  in  urine,  624 
Spermin,  517 
Spirits  of  glonoin,  431 

of  hartshorn,  233 

of  mindererus,  234 

of  wine,  395,  397 

proof,  395 

-wood,  396 
Spiritus  setheris  nitrosi,  405,  431 

ammoniae,  233 
Squibb's  fluid,  593 
Standard  solutions,  125 
Standards,  dietary,  542 
Stannic  acid,  298 

chlorid,  298 

sulphid,  299 


6S2 


INDEX 


Stannous  chlorid,  298 

hydroxid,  298 

sulphid,  299 
Stannum,  298 
Starch,  440 

iodized,  146 

solution,  440 
Steapsin,  428,  429,  556 
Stearic  acid,  427 
Stearin,  427 
Stearoptens,  453 
Steel,  337 
Stercobilin,  559 
Stereo-isomerism,  423 
Sterilization,  566 
Stibium,  291 
Stokes'  reagent,  529 
Stomach,  544 

contents,  544 

tube,  547 
Strontia,  236,  245 
Strontianite,  245 
Strontium,  245 

analytic  reactions  of,  245 

carbonate,  245 

oxid,  245 

Structure  of  flame,  113 
Strychnin,  503,  510 

sulphate,  510 

and  ptomains,  517 
description  of,  510 
fatal  dose  of,  510 
period  of,  510 
signs  of  poisoning  by,  510 
Sturin,  527 
Sublimation,  85,  150 
Sublimed  sulphur,  150 
Substances,  properties  of,  17 
Substitution,  384 

products  of  benzene,  449 
Succinic  acid,  421 
Succus  entericus,  559 
Sucrose,  437 
Sugar,  438 

barley,  438 

beet,  438 

cane-,  ^  43  7 

detection  of,  in  urine,  600 

fruit,  436 

grape-,  435 

inverted,  436 

of  lead,  323 

milk,  438 

muscle-,  437 
Sugars,  433 

compound,  433 

simple,  433 
Sulphaldehyd,  407 
Sulphanion,  135,  160 
Sulphates,  reactions  of,  166 
Sulphids,  reactions  of,  156 
Sulphites,  reactions  of,  159 
Sulphocarbolates,  458 


Sulphocyanates,  190,  345 
Sulphocyanic  acid,  190,  345 
Sulphonal,  415 
Sulphone,  415 
Sulphonethylmethane,  415 
Sulphonic  acid,  415 
Sulphonmethane,  415 
Sulphophenolates,  458 
Sulphur,  150 

content,  367 

derivatives  of  paraffins,  414 

determination  in  organic  compounds, 


157,  159 
flowers  of,  150 
group,  1  68 

in  proteid  molecule,  367 
milk  of,  151 
precipitated,  151 
sublimed,  151 
trioxid    160 
water,  256 

Sulphurated  antimony,  291 
Sulphuretted  hydrogen,  155 
Sulphuric  acid,  160 
antidotes  to,  165 
dilute,  162 
fuming,  162 
impurities  of,  161 
Nordhausen,  162 
toxicology,  163 
detection  of,  166 
fatal  dose  of,  164 

period  of,  164 

local  external  effects  of,  163 
poisoning  from,  163 

postmortem  appearances,  165 
symptoms,  164 
treatment,  165 
properties  of,  161 
quantitative  test  for,  167 
tests  for,  1  66 
ether,  403 
Sulphurous  acid,  158 

anhydrid,  157 
Sulphydric  acid,  156 
Supercooled  water,  43 
Superphosphate  of  lime,  241 
Sweet  spirit  of  niter,  405,  431 
Symbols,  function  of,  112 
Synaptase,  539 
Synthesis,  63 
Syntonin,  533,  534 
Syrupus  acidi  hydriodici,  147 
"calcii  lactophosphatis,  241 
calcis,  238 


TALC,  251 
Tallow,  426 
Tannic  acid,  470 
Tannin,  470 
Tanret's  test,  612 


INDEX 


653 


Tantalum,  117 
Tar,  445 
Tartar,  423 

cream  of,  423 

crude,  423 

emetic,  292 
Tartaric  acid,  423 
Tartrates,  reactions  of,  426 
Taurin,  501,  558 
Taurocholic  acid,  558 
Tea,  491 

Teissier's  test,  586 
Tellurium,  168 
Tenacity,  28 
Tension  of  aqueous  vapor,  40,  44 

of  gases,  29 
Terebene,  453 
Terebenthene,  452 
Terpenes,  452 
Terpin,  451 
Test-breakfast,  547 

-meal,  547 
Tetanin,  518 
Tetanotoxin,  518 
Tetronal,  415,  416 
Thalleioquin,  509 
Thallin,  488 
Thallium,  56,  117 
Thein,  491 

Theobromin,  490,  491 
Theophyllin,  490,  491 
Thermometers,  31,  32 
Thio-alcohols,  414 

-ethers,  414 

-ketones,  414 

-sulphuric  acid,  168 
Thorium,  248,  249,  361 
Thrombase,  538,  545,  562 
Thymin,  491 
Thymol,  453,  579 

iodid,  453 
Tin,  298 

-amalgam,  298 

chlorids  of,  298 

-plate,  298 

-stone,  298 

toxicology,  299 

symptoms  of  poisoning  from,  299 
tests  for,  299 

Tinctura  ferri  chloridi,  340,  346 
Titanium,  117 
Titration,  126 
Titre,  126 

Tollen's  test,  401,  606 
Toluene,  446 
Toluol,  446 
Topfer's  reagent,  549 

test,  550 

Toxalbumins,  566 
Toxemia,  522 
Toxins,  520,  566 

food-,  521,  566 


Toxins,  infection,  522 
Treacle,  438 
Trichloracetic  acid,  420 
Trichloraldehyd,  410 
Trichlormethane,  385 
Triclinic  system  of  crystals,  154 
Triethylamin,  497 
Trimethylamin,  497 
Trinitro-cellulose,  443 

-phenol,  458 
Trional,  414,  416 
Trioses,  434 
Triple  phosphate,  587 
Trommer's  test,  60 1 
Tropan  alkaloids,  503 
Tropeolin  test,  548 
Tropic  acid,  506 
Tropin,  506 
Trypsin,  534,  537,  556 
Tryptophan,  500,  525,  556 
Tube-casts  in  urine,  620 
Tungsten,  117 
Turkey  red,  474 
Turmeric  test,  569 
Turpentine,  452 
Turpeth  mineral,  315 
Type-metal,  320 
Typhotoxin,  518 
Tyrosin,  500,  525,  623 
Tyrotoxicon,  518 


UFFELMANN'S  test,  552 

Ultimate  analysis,  365 

Uracil,  491 

Uranin,  89,  461 

Uranium,  248,  249,  361 

Urases,  538,  578 

Urates,  599 

Urea,  193,  200,  492,  495,  499,  535,  578, 

579>  585>  592 
determination  of,  593 
nitrate,  496,  592 
Uremia,  595 
Ureometer,  593 
Uric  acid,  488,  493,  535,  579,  627 

endogenous  and  exogenous,  493 
Uricolytic  enzyms,  539 
Uricometer,  596 
Urinary  calculi,  586,  593,  627 
examination,  576 
sediments,  577,  587,  599,  619 
Urine,  576 

acetone  in,  607 
acids  in,  584,  608 
air  in,  624 
albumin  in,  609 

boiling  test  for,  609 
Esbach's  test  for,  611 
Heller's  test  for,  610,  617 
nitric-acid  test  for,  616 
picric-acid  test  for,  611 


654 


INDEX 


Urine,  albumin  in,  Purdy's  method,  612 

salicyl-sulphonic  acid,  615 

Tanret's  test  for,  612 

trichloracetic  acid,  612 
albumose  in,  614 
alkapton  in,  582 
analysis,  576 
bacteria  in,  577,  625 
Bence-Jones'  protein,  616 
bile  in,  582,  618 
blood  in,  616 

calcium  oxalate  of,  591,  627 
calculi,  627 

centrifuge  tests  for,  577,  586 
chlorids  of,  579,  590 
chyle  in,  619 
color,  581 
composition,  579 
creatinin  in,  579 
cryoscopy  of,  39,  584 
cystin  in,  622 

deposits,  577,  587,  599,  619 
diazo-reaction,  626 
epithelium  in,  619 
glycuronic  acid  in,  607 
hematuria,  616 
hippuric  acid  in,  579 
leucin  in,  623 
mucin  of,  615 
normal,  579 

nucleo-albumins  of,  615 
pentose  in,  606 
phosphates  of,  579,  585 
polarimetry  of,  61 
preservation  of,  578 
pus  in,  618 
quantity  of,  579,  580 
reaction,  579,  584 
retention  of,  580 
saccharometer,  548 
secretion,  576 
solids  of,  579,  583 
specific  gravity,  579,  583 
spermatozoa  in,  624 
sugar  in,  600 

Bottger's  bismuth  test  for,  603 

Fehling's  test  for,  602 

fermentation  test  for,  604 

glycerin-cupric  test  for,  60 1 

Nylander's  test  for,  603 

phenylhydrazin  test  for,  481,  604 

picric-acid  test  for,  603 

polariscope  test  for,  61 

Purdy's  test  for,  602 
sulphates  of,  579,  588 
suppression  of,  580 
tube-casts  in,  620 

epithelial,  621 

fatty,  622 

granular,  622 

hyaline,  621 

mucous,  621 


Urine,  tube-casts  waxy  in,  621 

ty rosin  in,  623 

urates  in,  599,  627 

urea  in,  496,  579,  592 

uric  acid  in,  488,  579,  595,  627 
Urinometer,  583 
Urobilin,  559,  581,  618 
Urochrome,  581 
Uroerythrin,  581 
Urorosein,  582 
Urotropin,  498 
Uroxanthin,  497 


VALENCE,  114,  251 
Valerates,  417 
Valeric  acid,  421 
Vanillin,  464 
Vapor  density,  26 

tension,  30,  40,  44 
Vaporization,  latent  heat  of,  42 
Vaselin,  379 

Velocities  of  reactions,  83 
Veratrin,  515 

reactions  of,  516 
Verdigris,  303 
Vermillion,  312 
Vinegar,  419 
Vitellin,  533 
Vitellose,  533 
Vitriol,  blue,  303 

green,  342 

oil  of,  1 60 

white,  355  _ 
Volatile  alkali,  231 
Volt,  50  _ 

Volumetric  analysis,  126,  349 
Vulcanized  rubber,  193,  291 

WASHING  soda,  226,  227 
Water,  83,  256 

alkaline,  256 

alum  in,  255 

ammonia  in,  262 

-analysis,  260 

bacillus  coli  in,  261 

biologic  test,  261 

carbonated,  256 

chalybeate,  85,  256 

chlorids  in,  261 

of  crystallization,  83 

distilled,  85 

drinking,  257 

ground,  257 

hard,  258 

of  hydra tion,  83 

maximum  density  of,  84 

mineral,  85,  256 

organic  matter  in,  262 

rain,  257 

saline,  256 

soft,  258 


INDEX 


655 


Water  storage,  260 

sulphur,  85,  256 

surface,  257 

well,  258 
Watt,  50 
Waves  of  ether,  58 

actinic,  58 

heat,  58 

Hertzian,  58 

luminous,  58 
Wax,  429 

Weathering  of  rocks,  207 
Weight,  18 

atomic,  109 

molecular,  no 

specific,  22 
Whey,  566 
Whisky,  397 
White  arsenic,  266 

damp,  101 

lead,  322 

precipitate,  312 

vitriol,  355 
Widal's  test,  523 
Wine,  397 

of  antimony,  292 
Winslow's  Soothing  Syrup,  512 
Wintergreen  oil,  468 
Witherite,  245 
Wood-alcohol,  392 

-naphtha,  392 

-spirit,  392,  419 
Wrist-drop,  305 
Wrought  iron,  337 


Xanthin,  489,  490 

bases,  489 

Xantho-proteic  reaction,  459,  526 
Xenon,  98 
X-rays,  54 


Xylene,  446,  451 
Xylol,  446,  451 
Xylose,  437 


YEAST,  396 

powders,  alum  in,  255 
Yellow  oxid  of  mercury,  308 

prussiate  of  potash,  345 

subsulphate  of  mercury,  313 

-wash,  308 
Ytterbium,  117,  251 
Yttrium,  117,  251 


ZERO,  31 

absolute,  32 
Zinc,  353 

acetate,  354 

antidotes  to,  356 

-blende,  353 

carbonate,  354 

chlorid,  355 

ferrocyanid,  357 

fever,  354 

hydroxid,  354 

ion  of,  353 

lactate.  354 

oxid,  353 

phenol  sulphonate,  458 

phosphid,  354 

sulphate,  355 

toxicology,  355 
detection  of,  357 
fatal  dose  and  period  of,  356 
tests  for,  357 
treatment  of  poisoning  from,  356 

-white,  354 
Zirconium,  117 
Zymase,  396 
Zymogen,  556 


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Weights  and  Measures ;  Dose-List,  and  a  Glossary  of  the  Terms  used 
in  Materia  Medica  and  Therapeutics.  By  EMILY  A.  M.  STONEY,  of  the* 
Carney  Hospital,  South  Boston.  I2mo  of  3<DOpages.  Cloth,  #1.50  net: 

THE    NEW  (3d)    EDITION 

In  making  the  revision  for  this  new  third  edition,  all  the  newer  drugs  have 
been  introduced  and  fully  discussed.  The  consideration  of  the  drugs  includes 
their  sources  and  composition,  their  various  preparations,  physiologic  actions, 
directions  for  administering,  and  the  symptoms  and  treatment  of  poisoning. 

Journal  of  the  American  Medical  Association 

"  So  far  as  we  can  see,  it  contains  everything  that  a  nurse  ought  to  know  in  regard  to  drug*. 
As  a  reference-book  for  nurses  it  will  without  question  be  very  useful." 


SAUNDERS'    BOOKS   ON 


Stoney's  Nursing 


Practical  Points  in  Nursing :  for  Nurses  in  Private  Practice.  By 
EMILY  A.  M.  STONEY,  Superintendent  of  the  Training  School  for  Nurses 
at  the  Carney  Hospital,  South  Boston,  Mass.  12  mo.  of  495  pages, 
fully  illustrated.  Cloth,  #1.75  net. 

THE  NEW  (4th)  EDITION 

In  this  volume  the  author  explains  the  entire  range  of  private  nursing  as  dis- 
tinguished from  hospital  nursing,  and  the  nurse  is  instructed  how  best  to  meet  the 
various  emergencies  of  medical  and  surgical  cases  when  distant  from  medical  or 
surgical  aid  or  when  thrown  on  her  own  resources.  An  especially  valuable  feature 
will  be  found  in  the  directions  how  to  improvise  everything  ordinarily  needed  in  the 
sick-room. 

The  Lancet,  London 

"A  very  complete  exposition  of  practical  nursing  in  its  various  branches,  including  obstetric 
and  gynecologic  nursing.     The  instructions  given  are  full  of  useful  detail." 


Stoney's  Technic  for  Nurses 

Bacteriology  and  Surgical  Technic  for  Nurses.  By  EMILY  A.  M. 
STONEY,  Superintendent  at  Carney  Hospital,  South  Boston.  Revised 
by  FREDERIC  R.  GRIFFITH,  M.  D.,  Surgeon,  of  New  York.  i2mo, 
311  pages,  illustrated.  Cloth,  $1.50  net. 

THE     NEW    (3d)     EDITION 
Trained  Nurse  and  Hospital  Review 

"  These  subjects  are  treated  most  accurately  and  up  to  date,  without  the  superfluous  reading 
which  is  so  often  employed.  .  .  .  Nurses  will  find  this  book  of  the  greatest  value  both  during 
their  hospital  course  and  in  private  practice." 

Spratling  on  Epilepsy 

Epilepsy  and  Its  Treatment.  By  WILLIAM  P.  SPRATLING,  M.  D., 
Medical  Superintendent  of  the  Craig  Colony  for  Epileptics,  Sonyea, 
New  York.  Octavo  of  522  pages,  fully  illustrated.  Cloth,  $4.00  net 

The  Lancet,  London 

"  Dr.  Spratling's  work  is  written  throughout  in  a  clear  and  readable  style.  .  .  .  The  work 
is  a  mine  of  information  on  the  whole  subject  of  epilepsy  and  its  treatment." 


NURSING. 


Aikens'  Primary  Studies  for  Nurses  illustrated 

PRIMARY  STUDIES  FOR  NURSES  :  A  Text-Book  for  First-year  Pupil 
Nurses.  By  CHARLOTTE  A.  AIKENS,  formerly  Director  of  Sibley  Memorial 
Hospital,  Washington,  D.  C.  i2mo  of  450  pages,  illus.  Cloth,  11.75  net- 

This  work  brings  together  in  concise  form  well-rounded  courses  of  lessons 
in  all  subjects  which,  with  practical  nursing  technic,  constitute  the  primary 
studies  in  a  nursing  course. 

Trained  Nurse  and  Hospital  Review 

"  It  is  safe  to  say  that  any  pupil  who  has  mastered  even  the  major  portion  of  this  work 
would  be  one  of  the  best  prepared  first-year  pupils  that  ever  stood  for  examination." 

Aikens'  Clinical  Studies  for  Nurses  rStvH^ 

CLINICAL  STUDIES  FOR  NURSES.  By  CHARLOTTE  A.  AIKENS,  formerly 
Director  of  Sibley  Memorial  Hospital,  Washington,  D.  C.  i2mo  of 
510  pages,  illustrated.  Cloth,  $2.00  net. 

This  new  work  is  written  along  the  same  lines  as  Miss  Aikens'  former 
work  on  ' '  Primary  Studies, ' '  to  which  it  is  a  companion  volume.  It  takes 
up  all  subjects  taught  during  the  second  and  third  years  and  takes  them 
up  in  a  concise,  forceful  way. 

Dietetic  and  Hygienic  Gazette 

"  There  is  a  large  amount  of  practical  information  in  this  book  which  the  experienced 
nurse,  as  well  as  the  undergraduate,  will  consult  with  profit.  The  illustrations  are 
numerous  and  well  selected." 

Aikens'  Training-School  Methods 

HOSPITAL  TRAINING-SCHOOL  METHODS  AND  THE  HEAD  NURSE.  By 
CHARLOTTE  A.  AIKENS,  formerly  Director  of  Sibley  Memorial  Hospital, 
Washington,  D.  C.  12 mo  of  267  pages.  Cloth,  £1.50  net. 

Trained  Nurse  and  Hospital  Review 

"  There  is  not  a  chapter  in  the  book  that  does  not  contain  valuable  suggestions." 

Aikens9  Hospital  Management  Jmt  Ready 

HOSPITAL  MANAGEMENT.  BY  CHARLOTTE  A.  AIKENS,  formerly  Direc- 
tor of  Sibley  Memorial  Hospital,  Washington,  D.  C.  i2mo  of  488 
pages,  illustrated.  Cloth,  $3.00  net. 

Miss  Aikens'  long  experience  as  hospital  director  has  well  fitted  her  to 
write  on  this  subject.  Her  book  is  a  concise,  careful,  and  thoughtful  discus- 
sion of  the  subject,  presented  in  a  way  that  must  strike  home  at  once. 


SAUNDERS*    BOOKS    ON 


Hoxie's  Medicine  for  Nurses 

Practice  of  Medicine  for  Nurses.  A  Text-Book  for  Nurses  and  Students 
of  Domestic  Science,  and  a  Hand-Book  for  All  Those  Who  Care  for  the  Sick. 
By  GEORGE  HOWARD  HOXIE,  M.  D.,  Professor  of  Internal  Medicine,  Uni- 
versity of  Kansas.  With  a  Chapter  on  Technic  of  Nursing  by  PEARL  L. 
LAPTAD,  Principal  of  the  Training  School  for  Nurses,  University  of  Kansas. 
I2mo  of  284  pages,  illustrated.  Cloth,  11.50  net. 

This  work  is  truly  a  practice  of  medicine  for  the  nurse,  enabling  her  to  recognize  any 
signs  and  changes  that  may  occur  between  visits  of  the  physician,  and,  if  necessary,  to 
combat  them  until  the  physician's  arrival.  This  information  the  author  presents  in  a  way 
most  acceptable,  particularly  emphasizing  the  nurse's  part. 

Trained  Nurse  and  Hospital  Review 

"  This  book  has  our  unqualified  approval." 


McCombs'  Diseases  of  Children  for  Nurses  New  (2d 

Diseases  of  Children  for  Nurses.  By  ROBERT  S.  McCoMBS,  M.  D., 
Instructor  of  Nurses  at  the  Children's  Hospital  of  Philadelphia.  I2mo  of 
470  pages,  illustrated.  Cloth,  $2.00  net. 

Dr.  McCombs'  experience  in  lecturing  to  nurses  has  enabled  him  to  emphasize  just  those 
points  that  nurses  most  need  to  know.  The  nursing  side  has  been  written  by  head  nurses, 
especially  praiseworthy  being  the  work  of  Miss  Jennie  Manly. 

National  Hospital  Record 

"  We  have  needed  a  good  work  on  children's  diseases  adapted  for  nurses'  use,  and  this 
volume  admirably  fills  the  want." 

Wilson's   Obstetric   Nursing 

A  Reference  Hand  =  Book  of  Obstetric  Nursing.  By  W.  REYNOLDS 
WILSON,  M.  D.,  Visiting  Physician  to  the  Philadelphia  Lying-in  Charity. 
32mo  of  258  pages,  illustrated.  Flexible  leather,  $1.25  net. 

Dr.  Wilson's  work  discusses  the  subject  of  obstetrics  entirely  from  the  nurse's  point  of 
view,  presenting  in  detail  everything  connected  with  pregnancy  and  labor  and  their  man- 
agement. The  text  is  copiously  illustrated. 

American  Journal  of  Obstetrics 

"  Every  page  emphasizes  the  nurse's  relation  to  the  case." 

Fruhwald  and  Westcott  on  Children 

Diseases  of  Children.  A  Practical  Reference  Book  for  Students  and 
Practitioners.  By  PROFESSOR  DR.  FERDINAND  FRUHWALD,  of  Vienna. 
Edited,  with  additions,  by  THOMPSON  S.  WESTCOTT,  M.  D.,  University  of 
Pennsylvania.  Octavo,  533  pages,  176  illustrations.  Cloth,  $4.50  net. 

Boyd's  State  Registration  for  Nurses 

State  Registration  for  Nurses.  By  LOUIE  CROFT  BOYD,  R.  N.  ,  Graduate 
Colorado  Training-school  for  Nurses.  Octavo  of  42  pages.  50  cents  net. 


NURSING. 


Macfarlane's  Gynecology  for  Nurses  illustrated 

A  REFERENCE  HAND-BOOK  OF  GYNECOLOGY  FOR  NURSES.  By  CATH- 
ARINE MACFARLANE,  M.  D.,  Gynecologist  to  the  Woman's  Hospital  of 
Philadelphia.  321110  of  150  pages,  with  70  illustrations.  Flexible 
leather,  $1.25  net. 

A.  M.  Seabrook,   M.  D.,    Woman's  Medical  College  of  Philadelphia. 

"  It  is  a  most  admirable  little  book,  covering  in  a  concise  but  attractive  way  the  subject  from 
the  nurse's  standpoint." 

Galbraith's  Personal  Hygiene  and  Physical  Training 

for  Women  Recently  Issued 

PERSONAL  HYGIENE  AND  PHYSICAL  TRAINING  FOR  WOMEN.  By 
ANNA  M.  GALBRAITH,  M.D.,  Fellow  New  York  Academy  of  Medicine, 
i2mo  of  371  pages,  with  original  illustrations.  Cloth,  $2.00  net. 

Dr.  Galbraith's  book  is  just  what  has  long  been  needed — a  simple  manual 
of  hygiene  and  physical  training  along  scientific  lines. 

De  Lee's   Obstetrics  for  Nurses  New  (3d)  Edition 

OBSTETRICS  FOR  NURSES.  By  JOSEPH  B.  DELEE,  M.  D.,  Professor  of 
Obstetrics  in  the  Northwestern  University  Medical  School.  i2mo  vol- 
ume of  512  pages,  fully  illustrated.  Cloth,  $2.50  net. 

J.  Clifton    Edgar,  M.  D., 

Professor  of  Obstetrics  and  Clinical  Midwifery,  Cornell  Medical  School,  N.  Y. 

"  It  is  far-and-away  the  best  that  has  come  to  my  notice,  and  I  shall  take  great  pleasure  in  recom- 
mending it  to  my  nurses  and  students  as  well." 

Davis'   Obstetric   Nursing  New  (3d)  Edition 

OBSTETRIC  AND  GYNECOLOGIC  NURSING.  By  EDWARD  P.  DAVIS,  A.  M., 
M.  D.,  Professor  of  Obstetrics,  Jefferson  Medical  College  and  Philadel- 
phia Polyclinic.  i2mo  of  436  pages,  illustrated.  Buckram,  $1.75  net. 

The  Lancet,  London 

"  Not  only  nurses,  but  even  newly  qualified  medical  men,  would  learn  a  great  deal  by  a  perusal  of 
this  book.  It  is  written  in  a  clear  and  pleasant  style,  and  is  a  work  we  can  recommend.  ' 

Beck's  Hand-Book  for  Nurses  New  (2d)  Edition 

A  REFERENCE  HAND-BOOK  FOR  NURSES.  By  AMANDA  K.  BECK,  of 
Chicago,  111.  32mo  of  200  pages.  Flexible  leather,  $1.25  net. 

This  little  book  contains  information  upon  every  question  that  comes  to  a 
nurse  in  her  daily  work,  and  embraces  all  the  information  that  she  requires 
to  carry  out  any  directions  given  by  the  physician. 

Boston  Medical  and  Surgical  Journal 

"  Must  be  regarded  as  an  extremely  useful  book,  not  only  for  nurses,  but  for  physicians.'* 


I0  SAUNDERS*    BOOKS   ON 

Register's  Fever  Nursing 

A  TEXT-BOOK  ON  PRACTICAL  FEVER  NURSING.  By  EDWARD  C. 
E.EGISTER,  M.  D.,  Professor  of  the  Practice  of  Medicine  in  the  North 
Carolina  Medical  College.  i2mo  of  352  pages.  Cloth,  £2.50  net. 

The  work  completely  covers  the  field  of  practical  fever  nursing.  The  illustrations  shovf 
the  nurse  how  to  perform  those  measures  that  come  within  her  province. 

Trained  Nurie  and  Hospital  Review 

"  Nurses  will  find  this  book  of  great  value  in  this  practical  branch  of  their  work." 

Hecker,  Trumpp,  and  Abt  on  Children 

ATLAS  AND  EPITOME  OF  DISEASES  OF  CHILDREN.  By  Dr.  R.  HECKER 
and  Dr.  J.  TRUMPP,  of  Munich.  Edited,  with  additions,  by  ISAAC  A. 
ABT,  M.D.,  Assistant  Professor  of  Diseases  of  Children,  Rush  Medical 
College,  Chicago.  With  48  colored  plates,  144  text-cuts,  and  453  pages 
of  text.  Cloth,  $5.00  net. 

The  many  excellent  lithographic  plates  represent  cases  seen  in  the  authors'  clinics,  and 
have  been  selected  with  great  care,  keeping  constantly  in  mind  the  practical  needs  of  the 
general  practitioner.  These  beautiful  pictures  are  so  true  to  nature  that  their  study  is 
equivalent  to  actual  clinical  observation.  The  editor,  Dr.  Isaac  A.  Abt,  has  added  all  new 
methods  of  treatment. 

Johns  Hopkins  Hospital  Bulletin 

"  The  entire  field  has  been  covered.  With  the  excellent  plates,  it  will  be  found  of  real 
value  to  both  students  and  practitioners." 

Lewis'  Anatomy  and   Physiology         Thc  New  <2d>  Edition 

ANATOMY  AND  PHYSIOLOGY  FOR  NURSES.  By  LsRov  LEWIS,  M.D., 
Surgeon  to  and  Lecturer  on  Anatomy  and  Physiology  for  Nurses  at  the 
Lewis  Hospital,  Bay  City,  Michigan.  i2mo  of  375  pages,  with  150 
illustrations.  Cloth,  $1.75  net. 

A  demand  for  such  a  work  as  this,  treating  the  subjects  from  the  nurses'  point  of  view, 
has  long  existed.  Dr.  Lewis  has  based  the  plan  and  scope  of  this  work  on  the  methods 
employed  by  him  in  teaching  these  branches,  making  the  text  unusually  simple  and  clear. 

The  Nurses  Journal  of  the  Pacific  Coast 

"  It  is  not  in  any  sense  rudimentary,  but  comprehensive  in  its  treatment  of  the  subjects 
in  hand.  The  application  of  the  knowledge  of  anatomy  in  the  care  of  the  patient  is 
emphasized." 

Friedenwald  and  Ruhrah's  Dietetics  New  (2d)  Edition 

DIETETICS  FOR  NURSES.  By  JULIUS  FRIEDENWALD,  M.  D.,  Professor 
of  Diseases  of  the  Stomach,  and  JOHN  RUHRAH,  M.  D.,  Professor  of 
Diseases  of  Children,  College  of  Physicians  and  Surgeons,  Baltimore. 
i2mo  volume  of  395  pages.  Cloth,  £1.50  net. 

This  work  has  been  prepared  to  meet  the  needs  of  the  nurse,  both  in  the  training 
school  and  after  graduation.  It  aims  to  give  the  essentials  of  dietetics,  considering  briefly 
the  physiology  of  digestion  and  the  various  classes  of  foods  and  the  part  they  play  in 
nutrition. 

American  Journal  of  Nursing 

"  It  is  exactly  the  book  for  which  nurses  and  others  have  long  and  vainly  sought.  A 
simple  manual  of  -dietetics,  which  does  not  turn  into  a  cook-book  at  the  end  of  the  first 
or  second  chapter. 


NURSING  AND  CHILDREN.  II 

Paul's  Fever  Nursing  New  (2d)$ti5ition 

NURSING  IN  THE  ACUTE  INFECTIOUS  FEVERS.  By  GEORGE  P.  PAUL, 
M.D.,  Assistant  Visiting  Physician  to  the  Samaritan  Hospital,  Troy,  N.  Y. 
i2mo  of  246  pages.  Cloth,  $1.00  net. 

Dr.  Paul  has  taken  great  pains  in  the  presentation  of  the  care  and  management  of  each 
fever.  The  book  treats  of  fevers  in  general,  then  each  fever  is  discussed  individually,  and 
the  latter  part  of  the  book  deals  with  practical  procedures  and  valuable  information. 

The  London  Lancet 

"  The  book  is  an  excellent  one  and  will  be  of  value  to  those  for  whom  it  is  intended. 
It  is  well  arranged,  the  text  is  clear  and  full,  and  the  illustrations  are  good." 

Paul's  Materia  Medica  for  Nurses 

MATERIA  MEDICA  FOR  NURSES.  By  GEORGE  P.  PAUL,  M.D.,  Assistant 
Visiting  Physician  to  the  Samaritan  Hospital,  Troy.  i2mo  of  240  pages, 
Cloth,  $1.50  net. 

Dr.  Paul  arranges  the  physiologic  actions  of  the  drugs  according  to  the  action  of  the 
drug  and  not  the  organ  acted  upon.  An  important  section  is  that  on  pretoxic  signs, 
giving  the  warnings  of  the  full  action  or  the  beginning  toxic  effects  of  the  drug,  which, 
if  heeded,  may  prevent  many  cases  of  drug  poisoning. 

The  Medical  Record,  New  York 

"This  volume  will  be  of  real  help  to  nurses;  the  material  is  well  selected  and  well 
arranged,  and  the  book  is  as  readable  as  it  is  useful." 

Pyle's  Personal  Hygiene  The  New  (4th)  Edition 

A  MANUAL  OF  PERSONAL  HYGIENE  :  Proper  Living  upon  a  Physiologic 
Basis.  By  Eminent  Specialists.  Edited  by  WALTER  L.  PYLE,  A.  M., 
M.D.,  Assistant  Surgeon  to  Wills  Eye  Hospital,  Philadelphia.  Octavo 
volume  of  472  pages,  fully  illustrated.  Cloth,  £1.50  net. 

To  this  new  edition  there  have  been  added,  and  fully  illustrated,  chapters  on  Domestic 
Hygiene   and    Home  Gymnastics,  besides  an  appendix  containing  methods  of  Hydro- 
therapy,   Mechanotherapy,  and  First  Aid  Measures.     There  is  also  a  Glossary  of  the 
medical  terms  used. 
Boston  Medical  and  Surgical  Journal 

"  The  work  has  been  excellently  done,  there  is  no  undue  repetition,  and  the  writers 
have  succeeded  unusually  well  in  presenting  facts  of  practical  significance  based  on  sound 
knowledge." 

Galbraith's  Four  Epochs  of  Woman's  Life     second  Edition 

THE   FOUR   EPOCHS  OF  WOMAN'S   LIFE.     By  ANNA  M.  GALBRAITH, 
M.D.      With  an  Introductory  Note  by  JOHN  H.  MUSSER,  M.D.,  Univer- 
sity of  Pennsylvania.      i2mo  of  247  pages.     Cloth,  11.50  net. 
Birmingham  Medical  Review 

"  We  do  not  as  a  rule  care  for  medical  books  written  for  the  instruction  of  the  public ; 
but  we  must  admit  that  the  advice  in  Dr.  Galbraith's  work  is  in  the  main  wise  and  whole- 
some." 

-  c 

Starr  on  Children  second  Edition 

AMERICAN  TEXT-BOOK  OF  DISEASES  OF  CHILDREN.  Edited  by  Louis 
STARR,  M.D.,  assisted  by  THOMPSON  S.  WESTCOTT,  M.D.  Octavo,  1244 
pages,  illustrated.  Cloth,  $7.00  net;  Half  Morocco,  $8.50  net. 


I2  SAUNDERS'    BOOKS    ON 

Brower  and  Bannister 
on  Insanity 

A  Practical  Manual  of  Insanity.  For  the  Student  and  General 
Practitioner.  By  DANIEL  R.  BROWER,  A.M.,  M.D.,  LL.  D.,  Professor 
of  Nervous  and  Mental  Diseases  in  Rush  Medical  College,  in  affiliation 
with  the  University  of  Chicago  ;  and  HENRY  M.  BANNISTER,  A.  M., 
M.  D.,  formerly  Senior  Assistant  Physician,  Illinois  Eastern  Hospital 
for  the  Insane.  Handsome  octavo  of  426  pages,  with  a  number  of 
full-page  inserts.  Cloth,  $3.00  net. 

FOR  STUDENT  AND  PRACTITIONER 

This  work,  intended  for  the  student  and  general  practitioner,  is  an  intelligible, 
up-to-date  exposition  of  the  leading  facts  of  psychiatry,  and  will  be  found  of  in- 
valuable service,  especially  to  the  busy  practitioner  unable  to  yield  the  time  for  a 
more  exhaustive  study.  The  work  has  been  rendered  more  practical  by  omitting 
elaborate  case  records  and  pathologic  details,  as  well  as  discussions  of  speculative 
and  controversial  questions. 

American  Medicine 

"  Commends  itself  for  lucid  expression  in  clear-cut  English,  so  essential  to  the  student  in 
any  department  of  medicine.  .  .  .  Treatment  is  one  of  the  best  features  of  the  book,  and  for 
this  aspect  is  especially  commended  to  general  practitioners." 

Bergey's  Hygiene 

The  Principles  of  Hygiene:  A  Practical  Manual  for  Students, 
Physicians,  and  Health  Officers.  By  D.  H.  BERGEY,  A.  M.,  M.  D., 
Assistant  Professor  of  Bacteriology  in  the  University  of  Pennsylvania. 
Octavo  volume  of  555  pages,  illustrated.  Cloth,  $3.00  net. 

THE  NEW  (3d)  EDITION 

This  book  is  intended  to  meet  the  needs  of  students  of  medicine  in  the 
acquirement  of  a  knowledge  of  those  principles  upon  which  modern  hygienic 
practises  are  based,  and  to  aid  physicians  and  health  officers  in  familiarizing 
themselves  with  the  advances  made  in  hygiene  and  sanitation  in  recent  years. 
This  new  third  edition  has  been  very  carefully  revised,  and  much  new  matter 
added,  so  as  to  include  the  most  recent  advancements. 

Buffalo  Medical  Journal 

"  It  will  be  found  of  value  to  the  practitioner  of  medicine  and  the  practical  sanitarian  ;  and 
students  of  architecture,  who  need  to  consider  problems  of  heating,  lighting,  ventilation,  water 
supply,  and  sewage  disposal,  may  consult  it  with  profit." 


CHILDREN  AND   HYGIENE.  13 

Griffith's  Care  of  the  Baby 

The  Care  of  the  Baby.  By  J.  P.  CROZER  GRIFFITH,  M.  D.,  Clinical 
Professor  of  Diseases  of  Children,  University  of  Penn. ;  Physician  to  the 
Children's  Hospital,  Phila.  I2mo,  455  pp.  Illustrated.  Cloth,  $1.50  net. 

THE  NEW  (5th)  EDITION 

The  author  has  endeavored  to  furnish  a  reliable  guide  for  mothers.  He  has 
made  his  statements  plain  and  easily  understood,  in  the  hope  that  the  volume 
may  be  of  service  not  only  to  mothers  and  nurses,  but  also  to  students  and  practi- 
tioners whose  opportunities  for  observing  children  have  been  limited. 

New  York  Medical  Journal 

"  We  are  confident  if  this  little  work  could  find  its  way  into  the  hands  of  every  trained 
nurse  and  of  every  mother,  infant  mortality  would  be  lessened  by  at  least  fifty  per  cent." 

Crothers*  Morphinism 

Morphinism  and  Narcomania  from  Opium,  Cocain,  Ether,  Chloral, 
Chloroform,  and  other  Narcotic  Drugs ;  also  the  Etiology,  Treatment, 
and  Medicolegal  Relations.  By  T.  D.  CROTHERS,  M.  D.,  Superintendent 
of  Walnut  Lodge  Hospital,  Hartford,  Conn.  Handsome  I2mo  of  351 
pages.  .Cloth,  $2.00  net. 

The  Lancet,  London 

"An  excellent  account  of  the  various  causes,  symptoms,  and  stages  of  morphinism,  the 
discussion  being  throughout  illuminated  by  an  abundance  of  facts  of  clinical,  psychological,  and 
social  interest." 

Ruhrah's   Diseases   of   Children 

A  Manual  of  Diseases  of  Children.  By  JOHN  RUHRAH,  M.  D., 
Professor  of  Diseases  of  Children,  College  of  Physicians  and  Surgeons, 
Baltimore.  I2mo  of  534  pages,  fully  illustrated.  Flexible  leather, 
$2.50  net. 

THE  NEW  (3d)  EDITION 

In  revising  this  work  for  the  second  edition  Dr.  Ruhrah  has  carefully  in- 
corporated all  the  latest  knowledge  on  the  subject.  All  the  important  facts  are 
given  concisely  and  explicitly,  the  therapeutics  of  infancy  and  childhood  being 
outlined  very  carefully  and  clearly.  There  are  also  directions  for  dosage  and 
prescribing,  and  many  useful  prescriptions  are  included. 

American  Journal  of  the  Medical  Sciences 

"  Treatment  has  been  satisfactorily  covered,  being  quite  in  accord  with  the  best  teaching, 
yet  withal  broadly  general  and  free  from  stock  prescriptions." 


I4  SAUNDERS1    BOOKS   ON 

Peterson  and  Haines' 
Legal  Medicine  &  Toxicology 


A  Text-Book  of  Legal  Medicine  and  Toxicology.  Edited  by 
FREDERICK  PETERSON,  M.  D.,  Professor  of  Psychiatry  in  the  College 
of  Physicians  and  Surgeons,  New  York;  and  WALTER  S.  HAINES, 
M.  D.,  Professor  of  Chemistry,  Pharmacy,  and  Toxicology,  Rush 
Medical  College,  in  affiliation  with  the  University  of  Chicago.  Two 
imperial  octavo  volumes  of  about  750  pages  each,  fully  illustrated. 
Per  volume:  Cloth,  $5.00  net;  Sheep  or  Half  Morocco,  $6.50  net- 
Sold  by  Subscription. 

IN  TWO  VOLUMES 

The  object  of  the  present  work  is  to  give  to  the  medical  and  legal  professions 
a  comprehensive  survey  of  forensic  medicine  and  toxicology  in  moderate  compass. 
This,  it  is  believed,  has  not  been  done  in  any  other  recent  work  in  English.  Under 
1 «  Expert  Evidence ' '  not  only  is  advice  given  to  medical  experts,  but  suggestions 
are  also  made  to  attorneys  as  to  the  best  methods  of  obtaining  the  desired  infor- 
mation from  the  witness.  An  interesting  and  important  chapter  is  that  on  ' '  The 
Destruction  and  Attempted  Destruction  of  the  Human  Body  by  Fire  and  Chemi- 
cals. ' '  A  chapter  not  usually  found  in  works  on  legal  medicine  is  that  on  ' '  The 
Medicolegal  Relations  of  the  X-Rays." 
Columbia  Law  Review 

"  For  practitioners  in  criminal  law  and  for  those  in  medicine  who  are  called  upon  to  give 
court  testimony  in  all  its  various  forms  ...  it  is  extremely  valuable." 


Fiske's  Human  Body 

Structure  and  Functions  of  the  Body.  By  ANNETTE  FISKE,  A.M., 
Graduate  of  the  Waltham  Training  School  for  Nurses.  I2mo  of  221 
pages,  illustrated.  Cloth,  $1.25  net. 

JUST  READY 

The  way  in  which  this  book  presents  anatomy  and  physiology  is  a  departure 
from  the  usual  method — a  departure,  however,  of  a  very  practical  kind.  Miss 
Fiske  has  woven  the  physiology  in  with  the  anatomy,  thus  making  her  work  a 
most  readable  one.  It  is  an  extremely  practical  book — one  that  can  be  readily 
understood. 


LEGAL   MEDICINE. 


Draper's  Legal  Medicine 

A  Text-Book  of  Legal  Medicine.  By  FRANK  WINTHROP  DRAPER,  A.  M., 
M.  D.,  Late  Professor  of  Legal  Medicine  in  Harvard  University,  Boston. 
Octavo  of  573  pages,  illustrated.  Cloth,  $4.00  net ;  Half  Morocco,  $5.50  net 

Hon.  Olin    Bryan,   LL.  B.,   Baltimore  Medical  College. 

"  A  careful  reading  of  Draper's  Legal  Medicine  convinces  me  of  the  excellent  character 
of  the  work.  It  is  comprehensive,  thorough,  and  must,  of  a  necessity,  prove  a  splendid 
acquisition  to  the  libraries  of  those  who  arc  interested  in  medical  jurisprudence." 

Chapman's  Medical  Jurisprudence  Third  Edition 

Medical  Jurisprudence,  Insanity,  and  Toxicology.  By  HENRY  C. 
CHAPMAN,  M.  D.,  late  Professor  of  Institutes  of  Medicine  and  Medical  Juris- 
prudence in  Jefferson  Medical  College,  Philadelphia.  I2mo  of  329  pages* 
illustrated.  Cloth,  $1.75  net. 

Golebiewski  and  Bailey's  Accident  Diseases 

Atlas  and  Epitome  of  Diseases  Caused  by  Accidents.      By   DR.   ED. 

GOLEBIEWSKI,  of  Berlin.  Edited,  with  additions,  by  PEARCE  BAILEY,  M.  D., 
Consulting  Neurologist  to  St.  Luke's  Hospital,  New  York.  With  71  colored 
illustrations  on  40  plates,  143  text  illustrations,  and  549  pages  of  text.  Cloth, 
$4.00  net.  In  Saunders'  Hand-Atlas  Series. 

Hofmann  and  Peterson's  Legal   Medicine 

Atlas  of  Legal  Medicine.  By  DR.  E.  VON  HOFMANN,  of  Vienna. 
Edited  by  FREDERICK  PETERSON,  M.  D.,  Professor  of  Psychiatry  in  the 
College  of  Physicians  and  Surgeons,  New  York.  With  120  colored  figures 
on  56  plates  and  193  half-tone  illustrations.  Cloth,  $3.50  net. 

Jakob  and  Fisher's  Nervous  System 

and     itS     Diseases  In  Saunders'  Hand- Atlases 

Atlas  and  Epitome  of  the  Nervous  System  and  its  Diseases.     By 

PROFESSOR  DR.  CHR.  JAKOB,  of  Erlangen.  From  the  Second  Revised 
German  Edition.  Edited,  with  additions,  by  EDWARD  D.  FISHER,  M.  D., 
Professor  of  Diseases  of  the  Nervous  System,  University  and  Belle vue 
Hospital  Medical  College,  New  York.  With  83  plates  and  copious  text. 
Cloth,  $3. 50  net. 

Abbott's  Transmissible  Diseases  second  Edition 

The  Hygiene  of  Transmissible  Diseases :  Their  Causes,  Modes  of  Dis- 
semination, and  Methods  of  Prevention.  By  A.  C.  ABBOTT,  M.  D.,  Pro- 
fessor of  Hygiene  and  Bacteriology,  University  of  Pennsylvania.  Octavo  of 
351  pages,  illustrated.  Cloth,  $2. 50  net. 


!6  SAUNDERS'   BOOKS  ON  CHILDREN. 

American  Pocket  Dictionary         just  Ready— New  (7th)  Edition 

AMERICAN  POCKET  MEDICAL  DICTIONARY.  Edited  by  W.  A.  NEW- 
MAN BORLAND,  M.  D.,  Editor  "American  Illustrated  Medical  Dic- 
tionary." Containing  the  pronunciation  and  definition  of  the  principal 
words  used  in  medicine  and  kindred  sciences,  with  64  extensive  tables. 
With  610  pages.  Flexible  leather,  with  gold  edges,  $1.00  net;  with 
patent  thumb  index,  $1.25  net. 

"  I  can  recommend  it  to  our  students  without  reserve." — J.  H.  HOLLAND,  M.  D.,  Dean 
of  the  Jefferson  Medical  College,  Philadelphia. 

Morrow's  Immediate  Care  of  Injured 

IMMEDIATE  CARE  OF  THE  INJURED.  By  ALBERT  S.  MORROW,  M.  D., 
Attending  Surgeon  to  the  New  York  City  Hospital  for  the  Aged  and 
Infirm.  Octavo  of  340  pages,  with  238  illustrations.  Cloth,  12.50  net 

Dr.  Morrow's  book  on  emergency  procedures  is  written  in  a  definite  and  decisive  style, 
the  reader  being  told  just  what  to  do  in  every  emergency.  It  is  a  practical  book  for  every 
day  use,  and  the  large  number  of  excellent  illustrations  can  not  but  make  the  treatment  to 
be  pursued  in  any  case  clear  and  intelligible.  Physicians  and  nurses  will  find  it  indispensible. 

Powell's  Diseases  of  Children  Third  edition.  Revised 

ESSENTIALS  OF  THE  DISEASES  OF  CHILDREN.  By  WILLIAM  M.  POWELL, 
M.  D.  Revised  by  ALFRED  HAND,  JR.,  A.  B.,  M.  D.,  Dispensary 
Physician  and  Pathologist  to  the  Children's  Hospital,  Philadelphia. 
i2rao  volume  of  259  pages.  Cloth,  |i.oo  net.  In  Saunders* 
Question-  Compend  Series. 

Shaw  on  Nervous  Diseases  and  Insanity      Fourth  Edition 

ESSENTIALS  OF  NERVOUS  DISEASES  AND  INSANITY:  Their  Symptoms 
and  Treatment.  A  Manual  for  Students  and  Practitioners.  By  the  late 
JOHN  C.  SHAW,  M.  D.,  Clinical  Professor  of  Diseases  of  the  Mind  and 
Nervous  System,  Long  Island  College  Hospital,  New  York.  i2mo  of 
204  pages,  illustrated.  Cloth,  $1.00  net.  In  Saunders'  Question- Com- 
pend Series. 

"  Clearly  and  intelligently  written ;  we  have  noted  few  inaccuracies  and  several  sug- 
gestive points.  Some  affections  unmentioned  in  many  of  the  large  text-books  are  noted." 
— Boston  Medical  and  Surgical  Journal, 

Starr's  Diets  for  Infants  and  Children 

DIETS  FOR  INFANTS  AND  CHILDREN  IN  HEALTH  AND  IN  DISEASE.  By 
Lops  STARR,  M.  D.,  Consulting  Pediatrist  to  the  Maternity  Hospital, 
Philadelphia.  230  blanks  (pocket-book  size).  Bound  in  flexible  leather, 
1 1. 25  net. 

Grafstrom's  Mechano-Therapy  second  Revised  Edition 

A  TEXT-BOOK  OF  MECHANO-THERAPY  (Massage  and  Medical  Gymnas- 
tics). By  AXEL  V.  GRAFSTROM,  B.  Sc.,  M.  D.,  Attending  Physician  to 
the  Gustavus  Adolphus  Orphange,  Jamestown,  New  York.  i2mo,  200 
pages,  illustrated.  Cloth,  $1.25  net. 


•y  <  *»•  '<<  •  ~  v,      4i 

! 

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BIOLOGY  LIBRARY 


APR  is  1941 


M&Y271965 


ftUG  1 3  1941 


OCT  1  0  1941 


OCT  2  9  1941 


1 7  1970 


JUN  5 


5 


JAN  i 


NOV     3 1950 


MAY 


^&195fr 


APK  3  0  1956 


o'6 


DEC  2-  1r 


;  ,-. 


BIOLOGY 


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